insulgard manual

InsulGard Continuously Online Partial Discharge Monitoring Installation and Operation Manual IB02713002E Rev. C Effective August 2011

InsulGard Installation and Operation Manual

InsulGard Installation and Operation Manual IB02713002E Rev. C Effective August 2011

EATON CORPORATION www.eaton.com/pd 2

Class A EMC Statements

FCC Part 15

NOTE: This equipment has been tested and found to comply with the limits for a Calss A digital device, pursuant to Part 15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful interference when the equipment is operated in a commercial environment. This equipment generates, uses, and can radiate radio frequency energy and, if not installed and used in accordance with the instruction manual, may cause harmful interference to radio communications. Operation of this equipment in a residential area is likely to cause harmful interference in which case the user will be required to correct the interference at own expense.

Requesting a Declaration of Conformity

The EC Declaration of Conformity is available upon request for products with a CE mark. For copies of the EC Declaration of Conformity, contact:

Eaton Predictive Diagnostics 5421 FELTL RD Suite 190 Minnetonka MN 55343 USA

Phone: (952) 912-1331 or (828) 687-3086

Fax: (952) 912-1355



Table of Contents Foreword................................................................................................................................................................... 7 1 Description ....................................................................................................................................................... 8

1.1 General..................................................................................................................................................... 8

1.2 Principles of Operation.......................................................................................................................... 10

1.3 Specification........................................................................................................................................... 12

1.4 Important Features and Options........................................................................................................... 14

1.4.1 Data Structure and storage. ................................................................................................................................14

1.4.2 Trend..................................................................................................................................................................14

1.4.3 Alarms ...............................................................................................................................................................14

1.4.4 Continuous Watch Feature.................................................................................................................................15

1.4.5 Phase Resolved Data and Phase Reference........................................................................................................15

1.4.6 Schedule.............................................................................................................................................................16

1.4.7 Self-test and Self-calibration..............................................................................................................................16

1.4.8 PD Intensity and PD pulse repetition rate calculation low level cut-off ............................................................16

1.4.9 Auxiliary Inputs .................................................................................................................................................16

1.4.10 Measurement Suspend ..................................................................................................................................16

1.4.11 Communication Options and Device Address ..............................................................................................17

1.4.12 Software ........................................................................................................................................................17

1.4.13 InsulGard configuration (settings) ................................................................................................................18

1.5 InsulGard mounting options and sensor connection ........................................................................... 19

1.5.1 Panel mount InsulGard ......................................................................................................................................20

1.5.2 Door mount InsulGard .......................................................................................................................................25

1.6 Sensors for InsulGard ........................................................................................................................... 27 2 Applications ................................................................................................................................................... 28

2.1 General................................................................................................................................................... 28

2.2 Motor and Small Generator Applications............................................................................................. 28

2.2.1 PD sensors at line terminals:..............................................................................................................................28

2.2.2 RTD sensors in winding depth...........................................................................................................................29

2.2.3 Auxiliary sensors ...............................................................................................................................................29

2.3 Large Generator Applications............................................................................................................... 29

2.3.1 PD sensors at line terminals:..............................................................................................................................29

2.3.2 RTD sensors in winding depth...........................................................................................................................30

2.4 MV Switchgear Applications................................................................................................................. 30

2.4.1 PD sensors .........................................................................................................................................................30

2.4.2 Auxiliary sensors ...............................................................................................................................................31



2.5 Configuration of Alarm Thresholds ..................................................................................................... 31

2.6 Noise Aspects ......................................................................................................................................... 31

2.7 Device Location and Environmental Issues ......................................................................................... 32

2.8 Additional Parameters to Measure ....................................................................................................... 32

2.9 Networking and Communicating with InsulGard................................................................................ 33 3 On-Site Installation ....................................................................................................................................... 34

3.1 InsulGard system content ...................................................................................................................... 34

3.2 InsulGard system packages ................................................................................................................... 35

3.3 Important Note on Sensor Installation ................................................................................................. 35

3.4 Step 1 - Hardware Installation.............................................................................................................. 36

3.5 Step 2 - Sensors and Power connections .............................................................................................. 37

3.6 Step 4 - Monitor Installation and Final Connections .......................................................................... 37 4 Startup............................................................................................................................................................ 38

4.1 General................................................................................................................................................... 38

4.2 Quick setting via the monitor keypad.................................................................................................... 38

4.3 Communications Board Setup .............................................................................................................. 41

4.3.1 USB ...................................................................................................................................................................41

4.3.2 Ethernet..............................................................................................................................................................41

4.3.3 Tips for Communications Setup ........................................................................................................................45 5 Troubleshooting............................................................................................................................................. 46

5.1 Troubleshooting Tips............................................................................................................................. 46

5.2 InsulGard replacement procedure ........................................................................................................ 48

5.3 Error Messages ...................................................................................................................................... 49

5.4 Fuse Replacement.................................................................................................................................. 49 6 Appendix I InsulGard Front Panel Keypad Operation............................................................................. 51

6.1 Entering Setup ....................................................................................................................................... 51

6.2 Setup via Keypad.................................................................................................................................... 51

6.2.1 Date....................................................................................................................................................................51

6.2.2 Time...................................................................................................................................................................52

6.2.3 Activate PD Channels........................................................................................................................................52

6.2.4 Parameters to Display ........................................................................................................................................52

6.2.5 Set a Sensor Sensitivity......................................................................................................................................55

6.2.6 Set Measurement Schedule ................................................................................................................................55

6.2.7 Data Saving Mode .............................................................................................................................................56

6.2.8 Pulse Width and Interval....................................................................................................................................57

6.2.9 Alarm Thresholds ..............................................................................................................................................57

6.2.10 Rated Voltage................................................................................................................................................58



6.2.11 Rated Current ................................................................................................................................................59

6.2.12 Number of Power Cycles for Data Acquisition.............................................................................................59

6.2.13 Alarm Relay Mode........................................................................................................................................60

6.2.14 Minimum Noise Channel Magnitude Level..................................................................................................60

6.2.15 Display Scroll Time ......................................................................................................................................61

6.2.16 ModBus Address...........................................................................................................................................61

6.2.17 Continuous Watch Options ...........................................................................................................................61

6.2.18 Baud Rate......................................................................................................................................................62

6.2.19 Select PDI or Qmax Output ..........................................................................................................................62

6.2.20 Start/Stop InsulGard......................................................................................................................................63

6.2.21 Phase Shift ....................................................................................................................................................63

6.2.22 Channel Phase ...............................................................................................................................................64

6.2.23 Frequency Range...........................................................................................................................................65

6.2.24 Suspend for Temperature ..............................................................................................................................65

6.2.25 Suspend for Voltage......................................................................................................................................66

6.2.26 Suspend for Current ......................................................................................................................................66

6.2.27 Trend Window Length ..................................................................................................................................67

6.2.28 Calibrate Temperature...................................................................................................................................67

6.2.29 Calibrate Voltage ..........................................................................................................................................68

6.2.30 Calibrate Current...........................................................................................................................................69

6.2.31 Calibrate 4-20mA Loop ................................................................................................................................70

6.2.32 Calibrate Humidity Sensor............................................................................................................................71

6.2.33 Noise Filter Offsets .......................................................................................................................................72

6.2.34 Channel Low Magnitude Limit .....................................................................................................................73

6.2.35 Software Filters .............................................................................................................................................74

6.2.36 ModBus Protocol ..........................................................................................................................................75

6.2.37 Start a Single Measurement ..........................................................................................................................75

6.3 Accessing Memory via Keypad.............................................................................................................. 75

6.3.1 Clear Data Memory ...........................................................................................................................................75

6.3.2 Check Data Saved in Memory ...........................................................................................................................76 7 Appendix II Synchronization and Phase Reference Shift.......................................................................... 77

7.1 Synchronization..................................................................................................................................... 77

7.2 Typical Phase Reference Shift for External Synchronization ............................................................. 78

7.3 Determining Phase Reference Shift...................................................................................................... 79 8 Appendix III Communications Board Interface ........................................................................................ 81

8.1 General................................................................................................................................................... 81

8.2 Network Configuration.......................................................................................................................... 81



8.3 Change Passwords................................................................................................................................. 85

8.4 Modbus RTU Configuration ................................................................................................................. 86

8.5 Date/Time Configuration ...................................................................................................................... 86

8.6 FTP Client Configuration ..................................................................................................................... 88

8.7 Email Configuration.............................................................................................................................. 88

8.8 Identification Page ................................................................................................................................ 92

8.9 InsulGard Summary Page..................................................................................................................... 93

8.10 InsulGard Channels Page ..................................................................................................................... 95

8.11 Alarms .................................................................................................................................................... 96

8.12 Logs ........................................................................................................................................................ 97

8.13 Documentation....................................................................................................................................... 97

8.14 Ethernet Virtual Communications Port................................................................................................ 98 9 Appendix IV USB Device Driver Installation............................................................................................. 99 10 Appendix V Ethernet Virtual Communications Port Driver Installation and Configuration............. 106

10.1 ComPortConfigurator User Manual................................................................................................... 106



Foreword

The purpose of this manual is to describe the functionality of the new generation of InsulGard. New features include a graphic dot matrix display and more communication options embedded, such as USB port, Ethernet port over network, webpage and FTP server. It serves as primary guideline for qualified personnel involved in the onsite installation, start-up, commissioning and continuous monitoring.

The whole document is organized in the following way:

Section 1 Description introduces the basic functions and operations of InsulGard

Section 2 Application presents the general considerations for InsulGard applications, especially configuration of different sensors for different applications.

Section 3 On-Site Installation shows the procedures for onsite installation of InsulGard systems.

Section 4 Startup presents the procedures for initial setup using the front panel keypad without a computer upon completion of InsulGard installation.

Section 5 Troubleshooting provides troubleshooting suggestions in different scenarios.

Section 6 Appendix I InsulGard Front Panel Keypad Operation gives details about how to operate using the front panel keypad and display on the InsulGard.

Section 7 Appendix II Synchronization and Phase Reference Shift shows the procedures to make proper synchronization and measure phase shift between InsulGard and monitored object.

The following three sections should be ignored if InsulGard does not include the optional communication board.

Section 8 Appendix III Communications Board Interface presents the features available through the optional communications board.

Section 9 Appendix IV USB Device Driver Installation gives exact steps to install the driver for communication between a computer and InsulGard with a USB cable through the USB port on the communication board.

Section 10 Appendix V Ethernet Virtual Communications Port Driver Installation gives exact steps to install the driver and configure the interface to use the Ethernet port on the communications board as a serial port to communicate between a computer and InsulGard online.



1 Description

1.1 General

InsulGard by Eaton Corporation is a standalone microprocessor-controlled continuous partial discharges monitoring device for use with a wide range of medium voltage power equipment. It works with 50/60 Hz frequency powered equipment as well as with variable frequency applications. There are monitors options for low frequency measurements down to 5 Hz and high frequency up to 400 Hz measurements .

Partial discharges (PD) are the small sparks that commonly occur within or on surface of insulation in various types of medium and high voltage equipment. Over time, PD destroys the insulation, eventually causing insulation breakdown (full discharge). In general, it takes months or even years before PD will cause a failure of insulation. Therefore, PD is an important indicator of insulation degradation for prompt maintenance or repair.

InsulGard is designed to provide an alarm based on PD characteristics at an early stage of insulation degradation. It measures PD from up to 15 high frequency PD sensors, stores the information in internal memory and provides various alarm interfaces to the users if any set points are exceeded. Depending on the application various PD sensors can be used.

InsulGard has three auxiliary inputs for measuring auxiliary parameters of the monitoring equipment: temperature, load and humidity or voltage, depending on the application. Those parameters will be correlated with Partial Discharge values for advanced data analysis. Corresponding sensors are supplied by Eaton.

InsulGard includes a main unit and a Sensor Interface Board connected by flat ribbon cable (Figure 1-1). All sensors have to be connected to the Sensor Interface Board.

Five LEDs on the front panel of the main unit indicate Alarm status: green LED for Normal, yellow LED for Warning (Alarm 1) and red LED for Alarm (Alarm 2), Setup and Memory operation modes.

A graphic LCD display shows measurement data, setup or memory content and error messages. During normal operation the display continuously scrolls through the last measured data, auxiliary parameters and other information.

With the front panel keypad and display, users can operate InsulGard directly without a computer. The membrane keypad has four navigation ARROW keys (), four function keys: Esc, d Enter,Set and Memory.

InsulGard has several interfaces (Figure 1-1) to be easily implemented into any alarm and SCADA system. These options include three C-form relays for Warning (Alarm 1), Alarm (Alarm 2) and Device Status indication, 4-20mA output, RS485 and two USB interfaces and an Ethernet interface which enable convenient online communication, webpage display and FTP server for data downloading.



a

b

Figure 1-1 a - Top: InsulGard main unit (right) and Sensor Interface Board (left). Bottom: b - Side view of the InsulGard.

15 channels for PD sensors connection and one channel for noise signal.

Connector for flat ribbon cable from main unit

Inputs for auxiliary sensors

connection



1.2 Principles of Operation

InsulGard has 16 signal channels. Channels 1 to 15 are designated for partial discharge sensors while channel 16 designated for noise suppression. All sixteen input channels have identical conditioning circuits (CC) that provide signal isolation, transient suppression, and high-pass filtering of the input signals. The frequency band of the PD signals for InsulGard is from 1 MHz to 20 MHz.

For each channel InsulGard acquires PD data in the form of three dimensional Phase-Resolved Pulse Height Distribution (PRPHD) - PD pulse count as a function of pulse magnitude and phase angle of monitored device voltage (60/50 Hz or voltage phase angle of a Variable Frequency Drive). Data are sorted into 24 phase windows (150 each) and 21 magnitude windows with magnitude dynamic range of ~70dB.

After data acquisition InsulGard firmware calculates integral PD parameters: Partial Discharge Intensity (PDI), Maximum Pulse magnitude (Qmax), Pulse Repetition Rate, and rate of upward trends of PDI and Qmax.

Partial Discharge Intensity (or Apparent PD power) is the value proportional to the power dissipated by partial discharges and represent damaging power of Partial Discharge. PDI measured in watts and defined as:

r

ni

i

iVUS

TPDI ***

1

1

=

=

=

Qmax defined as maximum repetitive magnitude of PD pulses. Above that magnitude pulse repetition rate must be at least 0.2 pulses per power cycle. Such approach will not take high magnitude random pulses as maximum PD magnitude.

Integral parameters are stored in internal data memory for each measurement, while PRPHD matrixes are stored only time to time to avoid data memory overfilling. This comprising two saving modes: Brief and Full or Normal and Test (in software settings). Each record is accompanied by time/date stamp and three auxiliary operating parameters: temperature, humidity, load current or voltage.

Before each measurement, InsulGard performs a self-test. If a problem detected, Status relay dry contacts open and an appropriate message appears on InsulGard display. Loss of power causes opening of status relay contacts too.

InsulGard acquires signals from the measurement channels sequentially multiplexing them to a single signal channel. Each pulse from each sensor is validated by the allowed pulse width. Noncompliant pulses will be discarded.

After each measurement, PDI, Qmax and Trend levels will be compared to preset Warning and Alarm thresholds for each active channel. If a warning threshold exceeded warning relay will operate and yellow LED will lit. If an alarm level is exceeded, InsulGard will trigger an additional measurement. If alarm condition will be confirmed, a red alarm LED will be turned on and the alarm relay will operate. Also phase resolved data will be stored in the memory and alarm event will be stored in log file in device memory.

Where:

T measurement time

S - sensitivity of the PD sensor (C/V)

n number of acquired PD pulses

Ui magnitude of a PD pulse

Vr rated voltage in the monitored equipment

pk08079Rectangle



PD measurements can be performed on a time schedule (up to 50 different times per day) or in specified time interval (from 1 minute to 23 hours 59 minutes) as long as the time interval is longer than a measurement time. Four scheduled measurements per day are recommended.

Between scheduled measurements, the Continuous Watch feature is enabled. All signal sensors are connected to a summation unit and then to a separate Continuous Watch channel. InsulGard continuously searches for an appearance of high magnitude pulses and pulse series. Magnitude threshold and repetition rate in series are configurable. If five events of pulse series are detected between the scheduled measurements, InsulGard will trigger PD measurement and display an alarm, if confirmed.

To provide correct measurements InsulGard must be synchronized with voltage frequency of the monitored equipment (see Section 7 Appendix II Synchronization and Phase Reference Shift) and must have correct settings for the type of equipment, rated voltage, and PD sensors used. All settings can be made using Setup mode from front panel keypad and display (see Section 6 Appendix I InsulGard Front Panel Keypad Operation ) or more easiliy using InsulGard PC software supplied with InsulGard (see InsulGard Software Manual). Eaton supplies monitors preconfigured based on ordering information.



1.3 Specification

General:

Applications HV and MV equipment (motors, including VFD, switchgear, generators, bus ducts, cable terminations, transformers, etc.)

Mounting options (1) In NEMA 4X enclosure.

(2) Panel Mount.

(3) Door (Flush) mount.

Installation category II

Pollution Degree 2

Temperature Range -400C - +85

0C (+70

0C for enclosure mount).

UL Certified for 00C - +70

0C ambient

Relative humidity 0%RH 90%RH

Maximum Altitude (m) 2000

Power Source 115V / 230V AC +/-10%

60 / 50 Hz

Power Consumption of device (VA max) 15 VA

Display Graphic Dot Matrix Display, 2 lines

Keypad 4 arrows and

4 function keys

LEDs InsulGard Status: Normal

Warning (Alarm 1)

Alarm (Alarm 2)

Memory mode

Setting mode

Approximate Size (Length x Width x Height) and Weight:

Main Unit 9.2x 7 x 2.5 (23.4cm x 17.8 cm x 6.4 cm)

4.2 lb (1.9 kg)

Door Mounted option (Main Unit with Sensor Interface Board)

9.2x 7 x 4 (23.4cm x 17.8 cm x 10.2 cm)

4.6 lb (2.1 kg)

Panel Mounted option 14.8 x 12.9 x 4 (37.6 cm x 32.8 cm x 10.2 cm)

10.3 lb (4.7 kg)

Enclosure (NEMA 4X) Mounted option 17.2 x 15.4 x 8.8, (43.7 cm x 39.0 cm x 22.3 cm)

21.6 lb ( 9.8 kg)

PD Measurement:

Number of PD Channels 15

PD Channel Magnitude Dynamic Range 68dB

Frequency Bandwidth 1-20MHz

Phase-Resolved Pulse Height Distribution (PRPHD):

Number of Magnitude Windows (3.23 dB each)

Number of Phase Windows (150 each)

21

24



Power Frequency at a Monitored Equipment (including VFD)

3-20Hz, 20-400Hz

Synchronization type Internal and External

Maximum Measured Pulse Repetition Rate 367,300 pulses/second

Integral PD Parameters Partial Discharge Intensity (PDI) Maximum Pulse Magnitude (Qmax) Pulse Repetition Rate, Trends of PDI and Qmax

Warning by PDI or Qmax

Alarm by PDI or Qmax and by Trends of PDI or Qmax

Number of Noise Channels 1

Continuous Watch (High PD activity) Function Active between measurements

Data Record Types Full/Brief (Test/Normal)

Internal Data Memory 2 MB. Provides up to 1000 days of data storage at 4 measurements per day

Self-test and Self-calibration At powering up and before every measurement

Setup Configurable from keypad and PC

Allowed RG-58 Coaxial Cable Length to PD Sensors Up to 150ft (50m)

Auxiliary Inputs:

Input specified for temperature measurement calibrated for 100 Platinum RTD sensor.

1

Analog Inputs specified for Current, Voltage or Humidity measurement

2

Interfaces:

C-form Dry Type Relays for:

Device Status

Warning (Alarm 1) and Alarm (Alarm 2) PD levels (fully configurable).

3

120VAC/ 5 Amps

28VDC/ 5 Amps

For other ratings refer to the relay specification

420 mA isolated interface represents Highest PDI or Max. Magnitude as % of the Alarm Threshold

Slope is 1mA per 10%

RS-485 interface optically-isolated (231 addresses). Communication Protocol: ModBus RTU, Binary,

Additional Communication Options USB for communication with PC

Ethernet, Webpage and FTP

Regulatory and Standards Compliance UL 61010-1: Second Edition Standard for Electrical Equipment for Laboratory Use, with revisions dated 2008-10-28

FCC Part 15, Subpart B, Class A

CAN/CSA C22.2 No. 61010-1-04, Second Edition, with revisions through 2008-10-01

IEC61010-1:2001 and EN61010-1:2001

EN61326-1, EN61000-3-2, EN61000-3-3

IEC61000-4-2, IEC61000-4-3, IEC61000-4-4, IEC61000-4-5, IEC61000-4-6, IEC61000-4-8, IEC61000-4-11



1.4 Important Features and Options

1.4.1 Data Structure and storage.

A Partial Discharge measurement results in Phase Resolved Partial Discharge Distribution (PRPDD) for every active channel. After each measurement for every active channel, InsulGard calculates integral PD parameters: Partial Discharge Intensity (PDI), maximum PD magnitude Qmax, Pulse Repetition rate (pulses per second) and Trend of PD activity (rate of PDI and Qmax change). The calculated parameters are compared to preset levels for Warning and Alarm operations.

All parameters with date/time stamp are stored in the internal memory for each measurement. Three auxiliary parameters (temperature, humidity, percentage of full load current or operating voltage) are added to each record.

Depending on what data will be stored in the internal memory, there are two modes of the Insulgard operation: Test mode and Normal mode.

Test Mode during this mode (PRPDD and calculated integral parameters for each channel are stored in the memory for every measurement. This is very memory-consuming mode, can overfill memory too soon, so stored data should be downloaded more often. Test mode saving initiated twice a month by default schedule. Schedule can be changed from keypad or software if necessary. The mode should be enabled for special testing.

Normal Mode during most of the measurements InsulGard will store the Brief version of PD data - only integral parameters without PRPDD (except scheduled Full saving mode measurements). This is a default mode for continuous monitoring.

InsulGard has 2 MB of internal flash memory for data storage. When the memory is filled, the device starts replacing the oldest data with the latest data. The rate of the memory consumption depends upon number of active channels, frequency of measurements, and frequency of PRPDD storage. AIf all 15 channels are active, measurements performed four times a day and PRPDD are stored twice a month, the device holds 17 months of the latest PD data in its internal memory. All stored data and settings can be accessed from the keypad or remotely from a PC.

1.4.2 Trend

InsulGard calculates trend of the parameter PDI or Qmax. Trend is calculated as a linear approximation of data over a specified time interval (default is 90 days). This specified time interval window is sliding over time while the device is monitoring PD. Trend is normalized to the value of the parameter change in times per year. Like PDI or Qmax levels, trend also has, Warning and Alarm thresholds . When the Warning or Alarm level exceeded, the corresponding LEDs on the front panel and relays will respond in the same manner as when PDI or Qmax levels are exceeded.

1.4.3 Alarms

InsulGard has two configurable alarm levels, Warning (Alarm 1) and Alarm (Alarm 2). There are two groups of parameters that can generate an alarm. One is the preset levels of PDI or Qmax for Warning and Alarm. The other is the preset trend levels for PDI or Qmax. Only one of two, PDI or Qmax, can be configured for alarming at any time.

The same parameter, PDI or Qmax is automatically configured for the 4-20 mA interface output. The 4-20 mA interface always represent the channel with the highest PD activity in terms of percentage of the channel alarm level with the slope 1mA/10%. An output of 4mA corresponds to 0% and 14mA



corresponds to 100% of the alarm level.

The alarm level for PDI is represented in terms of mW while the magnitude Qmax is represented in terms of mV.

Trend is set in terms of times per year for both PDI and Magnitude. Alarm on trend is enabled after a training period of 1/3 of the trend-sliding window.

A warning-level condition activates the corresponding relay and turns On yellow Warning LED immediately when warning condition is detected. When Alarm level exceeded, InsulGard will initiate an additional measurement, and only if alarm condition is confirmed alarm relay will operate and alarm LED will lit. If the Alarm conditions are not confirmed, the LED and Relay status will be set per the last measurement. If at any measurement the alarming status will be reduced, InsulGard will indicate the reduced alarming status with both LED and relay.

Alarm and Warning relays can operate in two modes (configurable). Relays lock in the status received at the last measurements, until the next measurement. Or a relay can operate for a limited configurable time and then release the contacts. At the next measurement, if an alarm/warning status is detected, the relay will hold the contacts closed for the same time. There is never operate option too (Off).

1.4.4 Continuous Watch Feature

Between the scheduled measurements Continuous Watch feature (High Alarm) is active. All sensors signals are summarized and connected to the separate High Alarm channel. InsulGard is continuously counting high magnitude pulses and series of such pulses with predefined number of pulses in series. If five series of high magnitude pulses detected, InsulGard starts regular PD measurement.

1.4.5 Phase Resolved Data and Phase Reference

In order to provide valid phase-resolved data, InsulGard must be synchronized with a signal that is synchronous with the voltage on the object being monitored. Phase shift between the voltage on monitored object and InsulGard power voltage should be obtained for that purpose.

There are two options for synchronization:

In most of cases the power source (115/230 VAC) powering up InsulGard is used as a synchronization signal. The device has an internal connection of the power circuit voltage to its synchronization circuitry. This option (default) always works on monitored objects powered from a regular power system (60/50Hz) in the area. Phase shift between monitors power voltage and the object high voltage should be determined during InsulGard startup and remains valid while the same object is monitored and the same power circuit is used. InsulGard allows for automated detection of a phase shift between its power circuit and an external phase reference signal. For detailed information on synchronization and phase reference shift detection refer to Section 7 Appendix II Synchronization and Phase Reference Shift.

Be cautious of an UPS power use it only if the UPS has constant phase shift to the voltage in the monitored object in Standby mode. If not, InsulGard will be in an asynchronous state and cant provide accurate phase-resolved measurements..

External synchronization should be continuously used if the InsulGard power supply voltage is not synchronous with the voltage on the test object. An example of an asynchronous test object is a variable frequency drive. An external synchronization signal should be continuously provided to the special synchronization input and appropriate jumpers in the device should be configured. Power frequency component of a signal applied to the channel #1 can be used for external synchronization if coupling capacitor is connected to that channel. For more information on synchronization and device



configuration refer to Section 7 Appendix II Synchronization and Phase Reference Shift.

1.4.6 Schedule

PD measurements can be performed at specified times during a day or in specified time intervals. Typically monitors are shipped with time basis schedule enabled and set to make measurements four times per day. This is sufficient for most of applications. If necessary, InsulGard can be set to measure up to 50 times per day at scheduled times or in specific time intervals varying from 1 minute to 23 hours 59 minutes as long as the time interval is shorter than the time of the measurement.

The time T required for a measurement is T 21*NCh*NC / F, where NCh number of active channels, NC number of cycles per acquisition, F synchronization frequency. Thus an InsulGard with all 15 channels active set for 60 cycles per acquisition and synchronized by 60 Hz would require 21*15*60/60=315 seconds, or 5 minutes and 15 seconds to complete a measurement.

1.4.7 Self-test and Self-calibration

InsulGard performs a self-test and calibration of PD signal and noise channels when powering up as well as before every PD measurement. If self-test fails the status relay contacts will open and a corresponding message will appear on the display.

1.4.8 PD Intensity and PD pulse repetition rate calculation low level cut-off

PDI and pulse count (PPS - pulse per second) are calculated for each channel at every measurement starting from some preset magnitude level (zone) and up. This feature allows for rejecting background noise from affecting PDI and pulse count calculations. Low magnitude calculation cutoff threshold can be set for each channel independently, based on its own background noise level, if any. There are options to set these values manually or automatically. Automatic low magnitude threshold detection can be launched only from the keypad (commonly during device start up or during the initial period of operation).

1.4.9 Auxiliary Inputs

It is well known that operating conditions of monitored equipment can significantly affect PD activity. Dependence of PD magnitude, repetition rate and PD intensity on temperature, humidity, system voltage and load current (in rotating machines) can provide valuable information for deeper analysis and increase diagnostic capabilities of PD monitoring. Calculation of correlations between PD parameters and operating conditions is a part of InsulGard software.

InsulGard has three auxiliary inputs. One of the inputs is solely designated for temperature measurement. A 100 platinum RTD can be used as a sensor. See the temperature sensor manual for details.

Two other inputs can accept any AC or DC signals within a specified voltage range. As factory default, they are configured for auxiliary sensors for load current and humidity measurement supplied by Eaton with an InsulGard.

1.4.10 Measurement Suspend

Measurements can be suspended in three different ways:

Monitoring can be stopped. The STOPPED message will be blinking on InsulGard display and Red Alarm LED will be ON. Monitoring must be resumed through keypad operation or software Resume



command by an operator.

Monitoring can be paused by software Pause command. In this case, monitoring will resume automatically in three hours.

Auto-suspend mode - can be controlled by any of three auxiliary parameters. The device allows an user for setting low and high thresholds for these three auxiliary parameters and enable the auto-suspend mode via keypad or via PC software. InsulGard will stop monitoring when any enabled auxiliary parameter is outside low - high boundaries range. The auto-suspend mode mostly used to suspend measurements in rotating machines by load current measurements when the machine is out of operation. For example, if low threshold for load current is set to 5% of the nominal current, InsulGard will stop making measurement when load current is 0 means that the monitored equipment is out of service. This keeps InsulGard from collecting meaningless data which can lead to incorrect trend calculations.

1.4.11 Communication Options and Device Address

InsulGard has various interfaces that allow for easy implementation into any alarm or SCADA system as well as for remote communications:

Three C-form relays dry contacts for Warning (Alarm 1), Alarm (Alarm 2) and Device Status indication.

4-20 mA isolated interface can be configured to represent PD Intensity (PDI) or Maximum PD magnitude (Qmax) to any SCADA system.

RS-485 optically isolated interface based on ModBus RTU protocol allows remote device configuration and data downloading. InsulGard can be networked with an existing ModBus network, allowing for up to 231 addressable devices.

InsulGard is shipped with the device address #1, otherwise different address was specified. The address can be changed only from the keypad and set to 1 - 231. In any case, the address must be unique in a particular local device network.

InsulGard is supplied with database software that allows automated communication with a device for data acquisition and analysis. The software allows either direct networking using a USB/Ethernet to RS485 converter or dial up connection to a device by a regular telephone landline or a cellular connection using appropriate modems with RS485 interface.

USB ports (only available with optional communications board): one USB port (Device) is for a direct link to a computer for communications with the InsulGard software or for communication board firmware upgrading, second USB port (Host) is reserved for future use.

Ethernet port (only available with optional communications board): It enables direct communication between computer and InsulGard and implementation into Ethernet network. Convenient online webpage and FTP server for data downloading or FTP client for data uploading are under construction.

Telephone landline or cellular modems with RS485 interface are optional.

1.4.12 Software

InsulGard software allows for communicating with InsulGard through a PC on a local RS-485 network or a modem. It also provides automated or manual data downloading and storage for multiple devices,



device setting, data analysis, and presentation (See InsulGard Software Manual).

1.4.13 InsulGard configuration (settings)

To get most of PD monitoring InsulGard have to be properly configured in accordance with the type of equipment to be monitored, system voltage, sensors used and preferable mode of monitoring. InsulGard is typically supplied preconfigured for particular equipment in accordance with available information received during ordering process.

Monitor configuration can be adjusted by changing firmware settings:

From InsulGard keypad (see Section 6 Appendix I InsulGard Front Panel Keypad Operation ),

From computer with help of software supplied with InsulGard monitor. The software has templates to help with configuration for typical applications (see InsulGard Software Manual).

There are few settings that can be configured only through the keypad. Refer to Section 4.1 for details.



1.5 InsulGard mounting options and sensor connection

InsulGard is can be shipped in one of the following configurations:

In NEMA-4X enclosure with or without transparent windows for outdoor installation(Figure 1-2 a).

On the panel (Figure 1-2 b) for installation in a cabinet. This option is identical to the first one, except that the panel is not mounted into an enclosure. Can be mounted into any custom cabinet including explosion-proof enclosure.

Door mount option. This option is used for indoor installation on a cabinet door (Figure 1-2 c, d, e). For door mount InsulGard Sensor Interface Board is mounted on the InsulGard back cover with temperature and humidity sensors typically installed inside Sensor Interface Board.

a

b

c

d

e

Figure 1-2 a, b IG installed on the panel and in NEMA 4 enclosure with window, c Door mount InsulGard, Sensor Interface Board is installed on the back of the InsulGard case, d, e - Door mount IG installed on a switchgear cabinet door (d - front and e - rear views)



1.5.1 Panel mount InsulGard

An example of a panel mounted InsulGard and its wiring diagram for 115 VAC power voltage is shown in Figure 1-3 a, b, c and Figure 1-4.

The InsulGard panel must be grounded at the place of its installation.

a - Front view.

Wire for panel grounding



b - Left side view.

c - Right side view

Figure 1-3 Panel mounted InsulGard



FUSES:Inside Insulgard for 115VAC application: Time-Lag 200mA, 250VAC, 5X20mm type 5ST by BEL Fuse Inc. , Catalog # 5ST 200.

On the panel: Fast Acting 3.0A, 250VAC, 5x20mm type 5MF by Bel Fuse Inc. Catalog # 5MF 3-R (or equivalent).

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B

LA

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ulG

ard

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ax

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rom

PD

Se

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ors

#1

-15

Ch1

Ch2

Ch4

Ch3

Ch5

Ch6

Ch8

Ch7

Ch9

Ch10

Ch12

Ch11

Ch13

Ch14

Ch16

(Noise)

Ch15

T

Se

ns

or

Inte

rfa

ce B

oa

rd

RTD

CT

H%

S

+5

S

Ref

5

S1

S2

6

7

8

9

10

11

12

4

3

2

1

Signal

Shield

H% RefSw

InsulGard'sconnectors

Co

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to S

en

so

r In

terf

ace

Bo

ard

Ground Screwon back cover

Ala

rmW

arn

ing

26

25

30

28

29

31

27 LINE

NEUTRAL

GROUND

+

4-2

0m

AA

larm

2

GL

N

Po

we

r

-+

5G

BA

RS

- 4

85

Sta

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Ala

rm 1

3

1

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8

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9

10

12

15

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24

WHITE

11

5 V

AC

GREEN

Connect Panelto Local Ground

DIN RAILGROUND

GREEN

RED

A L L

B L U E

GREEN

RTD-WHITE 1

RTD-BLACK 2

RTD-RED 3

LOAD-SIG-RED 4

LOAD-GND-BLACK 5

H%(GND)-WHITE 6

H%(+5V)-RED 7

H%(SIG)-BLACK 8

4-20mA- (+) 9

4-20mA- (-) 10

RS485-A(+) 11

RS485-B(-) 12

13

ALARM - NC 14

ALARM - COM 15

ALARM - NO 16

WARNING-NC 17

WARNING-COM 18

WARNING-N0 19

STATUS-NC 20

STATUS-COM 19

STATUS-NO 22

NOT/USED 23

NOT/USED 24

DIN

-Rail

Te

rmin

al S

trip

Cablesfrom:

RTD

TemperatureSensor

CT-Loadsensor

Humiditysensor

GR

L

N

WH

ITE

GR

EE

N

RE

D

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et

Devic

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ost

US

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Figure 1-4 A typical wiring diagram of the panel mounted InsulGard for 115VAC power voltage.

Note: For actual installation use the wiring diagram supplied with each InsulGard.)



All connections (excluding coaxial cables from PD sensors and connection to USB and Ethernet ports)

must be done to the terminal strip on the right side of the panel in accordance with panel wiring diagram supplied with each InsulGard. The table below: shows connection for typical wiring diagram of Figure 1-4.

Terminal # Connections Note

1 RTD sensor termination White wire (common)

2 RTD sensor termination Black wire (signal)

3 RTD sensor termination Red wire (signal)

4 CT Load sensor termination Red wire (signal)

5 CT Load sensor termination Black wire (common)

6 Humidity sensor termination White wire (common)

7 Humidity sensor termination Red wire (+5V output)

8 Humidity sensor termination Black wire (signal)

9 4-20mA current loop (+ ) output

10 4-20mA current loop ( - ) output

11 RS485 interface (A) RDA(+)

12 RS485 interface (B) RDB(-)

13 RS485 interface (insulated GND) Not connected

14 Alarm (Alarm 2) relay NC contact

15 Alarm (Alarm 2) relay COM contact

16 Alarm (Alarm 2) relay NO contact

17 Warning (Alarm 1) relay NC contact

18 Warning (Alarm 1) relay COM contact

19 Warning (Alarm 1) relay NO contact

20 Status relay NC contact

21 Status relay COM contact

22 Status relay NO contact

23 Spare terminal Not connected

24 Spare terminal Not connected

25 Line AC Power to InsulGard

26 Line AC Power to internal power outlet Outlet installed only for 120 VAC application

27 Line Incoming AC Power 115/230VAC, 60/50Hz to the internal fuse/disconnect

Users are responsible for an external circuit breaker

28 Neutral AC Power to internal power outlet

29 Neutral Incoming AC Power and Neutral to InsulGard

30 Ground AC Power to InsulGard and to internal power outlet

31 Ground Incoming AC Power and InsulGard chassis ground

Coaxial cables from PD sensors (and from the noise sensor if used) must be connected directly to the Sensor Interface Board (5 a). Connect the coaxial cables to their respective terminals at the Sensor Interface Board. Central wire connected to an upper terminal, coax cable shield connected to a

corresponding lower terminal (labeled on 1st channel).

To access Sensor Interface Board one should temporally remove the InsulGard monitor.



~1"

~0.3"

c

a

d

b

e

Figure 1-5 a, b - termination of PD sensors coax cables to the Sensor Interface Board, c cable preparation, d recommended stripper for RG58 cable, e Humidity/Phase Reference Switch.

Use blade crimp terminals on shield to avoid hairs and possible short circuit to the central wire. Distribute cables evenly and secure them in place with cable ties.

IDEAL part#45264 STRIP MASTER



H% / Ref switch (Figure 1-5 e) must be in the H% position during normal operation. Ref switch position is used only during phase shift measurement phase difference between external reference signal and internal IG synchronization (Section 7 Appendix II Synchronization and Phase Reference Shift). After that measurement switch must be switched back to the H% position.

1.5.2 Door mount InsulGard

In door mount version Sensor Interface Board is mounted on the InsulGard back cover (Figure 1-6).

Figure 1-6 Door (Flush) mount InsulGard (back view)

InsulGard must be grounded at the place of installation.

Power line and output signals (Status, Warning (Alarm1) and Alarm (Alarm2) relays, RS485 and 4-20mA interfaces) should be connected to InsulGard directly by plug-in connectors supplied with an InsulGard in accordance with the labels on the right side (Figure 1-3 c).

Wire to local ground

Jumper J1

Jumpers J7 & J8

H% / Ref Switch



All sensors should be connected directly to the Sensor Interface Board. Coaxial cables from PD sensors should be connected to Ch1-Ch15 inputs. Auxiliary sensors should be connected to the 12 contacts connector on the left side of the Sensor Interface Board as shown in Figure 1-7 and table below.

Figure 1-7 Auxiliary sensors connection to sensor interface board.

Auxiliary sensors connection:

Contact #

Sensor connected

Sensors wire Note

1 RTD common wire (white wire) Board common

2 RTD signal wire (black wire) Output dc current 2mA

3 RTD signal wire (red wire) Output dc current 2mA

4

Temperature sensor

100 Ohm Platinum RTD

Cable shield (optional) Board common

5 Signal wire (red wire) Input impedance 100 Ohm,

6

Load (CT) sensor Common wire (black wire) Board common

7 External Reference

Usually not used Input impedance > 27kOhm. Input voltage should not exceed 1VAC. Disconnect jumper 1 if external reference signal is used.

8 n/a test point

9 n/a Board common

10 Sensor common (white wire) Board common

11 + 5VDC for the sensor (red wire) Output current is limited by 100 Ohm resistor.

12

Humidity sensor

Output signal (black wire) Input impedance > 27kOhm. Input voltage should not exceed +5V.

Notes:

H% / Ref switch must be in the H% position during normal operation. Ref switch position is used only during phase shift measurement phase difference between external reference signal and inner IG synchronization (Section 7 Appendix II Synchronization and Phase Reference Shift). After this measurement switch must be switched back to the H% position.

Cables from:

Temperature sensor

Load (CT) sensor

(for motors)

Humidity sensor



Jumper 1 (Figure 1-6) must be removed if external reference signal (e.g. from potential transformer) applied to contact #7 on Sensor Interface Board (Section 7 Appendix II Synchronization and Phase Reference Shift).

For door mount InsulGard temperature and humidity sensors are usually installed inside Sensor Interface Board. Jumpers J7 & J8 must be installed that case.

1.6 Sensors for InsulGard

Wide variety of sensors for InsulGard monitor are manufactured by Eaton Corp.

Basic sensors are:

IPDS - Integrated Partial Discharge Sensors with voltage ratings 5-38kV - 80pF coupling capacitors with special protection circuitry built in.

RFCT - Radio Frequency Current Transformer.

RTD-6 - PD sensor. Resistive Temperature Detectors installed in a rotating machine stator work as a local RF antenna for PD pulses. This sensor connects up to 6 RTDs to capture PD signals originated in a stator winding. It designed as a single board replacing an existing RTD terminal board and does not affect temperature measurements.

IPDS RTD-6-PD RFCT

Figure 1-8 PD sensors

The auxiliary sensors:

TS - Temperature sensor - 3-wire 100 Ohm platinum RTD in protecting shell. For rotating machines using spare 100 Ohm platinum RTD in stator winding is preferable.

HS - Humidity sensor.

CT - Load (CT) sensor. 5 Amps primary current, ratio1000:1. Mostly used for rotating machines. It should be installed over secondary wire of an existent metering current transformer.

CTF - Split-core Primary Current Transformer (FlexCore) with CT sensor preinstalled on shortening jumper of Primary CT secondary winding. CTF used if there is no metering CT in feeder termination compartment and corresponding metering CT is too far from InsulGard. Install CTF around a feeder cable of any phase in a motor feeder termination enclosure. It must be installed over the shielded part of the feeder cable with cable shield grounding wire coming through the CT. In case of several feeders per phase, it is permissible installing CTF only around one of the feeders.

All above sensors have default cable length of 65 (20m). Specify other lengths if necessary. See the sensor manual for detailed information.



2 Applications

2.1 General

InsulGard is a versatile device that can be applied to most of medium and high voltage equipment. Specifics of a particular application (optional components and planning installation) should be taken into account to achieve high performance of PD monitoring.

Issues that should be considered are:

Type and specifics of equipment to monitor

Configuration of PD sensors

Noise aspects

Device location and environmental issues

Additional parameters to measure

Networking and Communicating to the device

Equipment with voltage ratings of 3kV and higher are considered reliable for PD diagnostic applications. Marginally, 2300V equipment can be considered, but the technology is inconclusive. It may or may not detect a significant problem at 2300V. In general, higher voltage provides greater destructive power for partial discharges and problems can be more reliably detected and predicted.

InsulGard was designed to monitor partial discharges in any MV equipment. Most frequent applications are in rotating machines, medium voltage switchgears, MV transformers and associated auxiliary equipment and connections. The connections may include cable terminations and portions of a cable or a bus feeding a device. InsulGard can also be used on other types of medium voltage and high voltage equipment. Particular applications of the technology may require special pre-engineering and adaptation. Consideration should be given while attempting to use InsulGard on high voltage equipment above 120kV. Noise in the form of aerial corona discharges should be addressed in such cases.

PD sensors configurations are application oriented, although there are some general guidelines can be applicable. Request Install Consideration and Sensor manuals documentation or/and discuss sensor installation with an Eaton Electrical application engineer.

2.2 Motor and Small Generator Applications

PD sensors for small generators and medium voltage motors typically include three sensors located at the line terminals and one or two RTD-PD sensors servicing six to twelve winding RTDs. Because of significant attenuation of high frequency signals in a motor winding, sensors located at the line terminals will not detect partial discharge in a winding depth; likewise, the sensors located in winding far from HV terminals will not sense discharges at the line terminal.

2.2.1 PD sensors at line terminals:

Coupling Capacitors. Typically Integrated Partial Discharge Sensors (IPDS) by Eaton with 80pF capacitance, but can use any kind of coupling capacitors. IPDS have sufficient insulation and connected directly to a motor line terminals. Those sensors exhibit the most noise-immune characteristics due to their low capacitance and, therefore, can suppress most low frequency



noise by themselves. Using IPDS is a highly recommended option for line terminals.

Note: Installation of line terminal sensors always requires an outage.

Radio Frequency Current Transformers (RFCT) placed on incoming feeders shield grounding conductor (one per phase) or on single-phase surge capacitor grounding conductor (one per phase). Using a single three-phase surge capacitor is possible, but not recommended because of low sensitivity to phase-to-phase partial discharge. The later is also valid for RFCT sensors on three phase feeder shield ground single wire. An advantage of RFCT sensors is that they are non-invasive (no connection to HV conductors is required). But RFCT sensors are less noise immune compare to IPDS sensors and more vulnerable to ground network noise. RFCT absolutely should not be used in Variable Frequency Drives environment with high magnitude and repetition rate pulse noise.

2.2.2 RTD sensors in winding depth

Besides line terminal area sensors, additional sensors are required to service larger area of a stator winding. RTD sensors embedded into a stator windings can be used for this purpose. An RTD supplies a DC temperature signal to a metering device. An RTD and RTD wires also operate as a RF antenna for high frequency signals generated by partial discharge. High frequency signals can be extracted and used to for detection of pulses originated by partial discharge in proximity of an RTD.

Eaton developed the RTD-6 PD sensor board with embedded filters to suppress external noise coming from temperature metering system or induced in control wiring by other equipment. This sensor is designed as a single board to replace an existing RTD terminal board in the closest to a motor/generator RTD terminal box. It does not affect temperature measurements, and extracts PD signals to be detected by InsulGard. Each board can handle up to six RTDs. If there are more than 6 RTDs, additional RTD -6 PD sensor board should be used. An RTD-6 board can be installed online which requires temporarily disabling temperature alarm or relay system.

2.2.3 Auxiliary sensors

Partial Discharge activity significantly varies with operating parameters. Winding temperature, load current, and humidity are the three most important parameters to correlate with a detected PD activity. Correlation of the detected PD activity with those parameters can provide invaluable information for enhanced diagnostics of insulation condition in a monitored equipment. Preferably use one of the winding RTDs for temperature measurement.

Note: One InsulGard device is required for a monitored object.

2.3 Large Generator Applications

Large generator application is, in general, similar to a motor or small generator application.

2.3.1 PD sensors at line terminals:

Coupling capacitors (IPDS) are commonly used as line terminal sensors. A generator equipped with iso-phase bus duct might have sparking in bus supporting insulators. A digital filter has been built into InsulGard firmware to distinguish that specific external PD activity from PD activity coming from a generator. Another option is using two sets of IPDS located at the terminals and at some distance along iso-phase bus for noise suppression.



2.3.2 RTD sensors in winding depth

Large machines can have several dozens RTDs embedded in the winding. Use 12 RTDs located in most electrically stressed parts of the stator winding, and evenly distributed along the stator winding to obtain maximum coverage of the stator. Making that choice can be a challenge even when winding diagram and RTD locations are available.

Large generators may have very long signal wires from an RTD to the first RTD termination. Also different kinds of RTD wires can have different signal propagation qualities. These factors can significantly affect high frequency signal propagation, attenuating a PD pulse. In order to minimize signal attenuation; RTD-6 board can be installed at the generator gland, where the RTD wires come out of the generator frame.

Certain generators do not have RTDs embedded into a stator winding. For example, large Westinghouse hydrogen cooled machines have RTDs only in cooling gas pipelines. These RTDs cannot be used as PD sensors. Verify that RTDs are located in a winding.

Auxiliary parameters are monitored in large generators same way as in motors. In hydrogen cooled generator hydrogen pressure might be monitored instead of humidity.

2.4 MV Switchgear Applications

Door mount InsulGard option commonly used in indoor switchgear lines.

2.4.1 PD sensors

Three major types of PD sensors are used for switchgear lines:

Three IPDS sensors (one per phase) are installed, as a rule of thumb, in every third cubicle. Therefore, each set of three IPDSs assess the cubicle where it is installed, and the cubicles on each sides. Increasing a distance between IPDS sets might cause some distant PD activity to be missed. Keep in mind that PD signals attenuate approximately twice from cubicle to cubicle. IPDS can be installed on a bus side or load side of a breaker. In the case of a load side, the sensor will not measure PD while the breaker is open, but can be installed without taking the whole bus out of operation. Installation on main bus requires full outage, but fewer sensors to service switchgear line. In general, one InsulGard can handle a switchgear line with up to 15 cubicles.

RFCT sensor(s) installed on the incoming and outgoing feeder shield grounding conductors; commonly, one per cubicle on all three phase feeder shield ground cable. Phase to phase signals can be missed in such a configuration. Installing three RFCT sensors (one per phase) can be considered for most critical feeders. RFCT sensors on cable shields are susceptible to ground noise and not applicable in high noise environment, particularly with FVD drives.

Combination of RFCT and IPDS sensors can make most effective sensor configuration. Consider more sensors in proximity of most critical parts of a line-up.

Eaton Corporation came up an idea and has implemented usage of stress shields in MV bushings in switchgear as coupling capacitors. Eaton manufactured switchgear can come equipped with PD monitoring system as an option. Consult Eaton application engineers on this opportunity.



2.4.2 Auxiliary sensors

Temperature and Humidity should be monitored in switchgear application. By default for door mount InsulGard in indoor applications temperature and humidity sensors are incorporated into sensors Interface Board. External sensors will be shipped if requested. If high voltage in the system can vary more than +/-5%, one can consider monitoring of that voltage too. That option requires reconfiguration of the jumpers on the Sensor Interface Board and changes in InsulGard and software settings.

2.5 Configuration of Alarm Thresholds

The Warning and Alarm thresholds for each PD channel of InsulGard are configurable. Thresholds depend on the type of PD sensor used (sensor sensitivity), system voltage, type of equipment, sensor location and adjacent connections. There are no universal standard values for Warning or Alarm thresholds. The following table shows typical values of the thresholds used as default settings in several applications:

Application Sensor Type PDI

Warning (mw)

PDI Alarm (mw)

Qmax Warning

(mV)

Qmax Alarm (mV)

5kV Motor / Small Generator

Coupling Capacitor 3 10 50 100

6.9kV Motor / Small Generator

Coupling Capacitor 10 30 100 500

6.9kV Motor / Small Generator

RTD 10 30 100 500

15kV Motor / Generator Coupling Capacitor 20 100 200 1000

15kV Motor / Generator RTD 20 100 200 1000

5 kV Switchgear Coupling Capacitor 3 5 50 100

15 kV Switchgear RFVS 3 10 50 200

15 kV Switchgear Coupling Capacitor 3 10 50 200

38 kV Switchgear RFCT 5 20 50 200

Since PD measurements in high frequency range are relative in nature, warning and alarm threshold should be corrected in every given case after initial period of monitoring and subsequent data analysis. Simple rule of thumb can be used: - in case of significant PD activity set warning threshold close to average level of PD activity, set alarm threshold a little below peak values of the detected PD activity, so that threshold will be exceeded infrequently and phase resolved data will be saved during such events;

- if PD activity is low, set warning level higher then peak readings and set alarm threshold twice higher then warning threshold.

2.6 Noise Aspects

Noise is a major issue in partial discharge measurement in industrial environment. Noise is site-related. There is no universal solution for noise suppression in modern state of technology, however most noise issues can be overcome. InsulGard has been designed with several noise suppressing algorithms and, along with recommended sensors, is able to suppress most of industrial noise. While planning InsulGard installation, keep in mind most common noise sources:



Pulse signals coming from incoming lines and feeders

PWM power sources for VFD drives (RFCT sensors cant be used on feeders in such environment)

Power thyristor firing

Switching power supplies in modern metering and protective electronics

Arcing and sparking somewhere at the facility

Aerial corona on overhead lines on high voltage substations

Partial discharges in the adjacent equipment

Ground network noise

High frequency noise from TV, Radio and communication transmission.

In some cases the source of noise can be identified and additional noise sensor(s) can be connected to the Noise channel to reject that noise from PD measurements.

2.7 Device Location and Environmental Issues

InsulGard can be shipped with or without an environmental enclosure. Without an enclosure, it can be used indoors in a relatively clean environment.

In most applications, indoor or outdoor, InsulGard comes in NEMA-4 plastic enclosure protecting the device from direct rain, sun, and dust. Use stainless steal enclosure in chemically aggressive environment. Explosion proof enclosure might be required in special cases.

In an indoor switchgear lineup InsulGard can be door mount without an enclosure.

When planning installing InsulGard, consider a non-vibrating location, conveniently located in a centralized position close to all sensors, control power line and communication lines (phone jack, conduits/tray to control room for alarms, etc.). It is recommended to keep the length of PD signal coaxial cables (50 Ohm RG58 or similar) as short as possible to decrease signal attenuation along the cable. Recommended maximum length is 150, but it is not a solid limitation.

2.8 Additional Parameters to Measure

Several factors can affect PD activity: temperature, humidity, voltage, mechanical vibration, etc. In North America system voltage commonly is not an issue. It is stable and does not affect PD significantly. If more than +/-5% voltage variation is expected, the voltage should be monitored and correlated to PD activity. Temperature is very important parameter for PD diagnostics of an insulation condition. Temperature variations change size of voids in solid insulation and surface conductivity which subsequently cause changes in PD activity. Humidity is also a factor affecting partial discharge, mostly through changes in surface conductivity, especially if combined with surface contamination. In hydrogen cooled machines monitoring of hydrogen pressure may be more beneficial than monitoring humidity. Changes in Load current affect vibration of coils in rotating machines and cause changes in slot and end-winding discharges. Correlation of PD activity changes to operating parameters can help distinguishing different types of partial discharge improve diagnostics capabilities and direct corrective measures.

Also zero load current (or voltage) could be used to suspend monitoring during equipment outage.



2.9 Networking and Communicating with InsulGard

InsulGard equipped with several interfaces allowing for implementation of a monitor into a control system or into instrumental network:

Dry contact C-form relays can provide warning, alarm and monitor status signals to an annunciator or to SCADA system. Alwa

insulgard manual

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