User’s manual and Technical description

Document No 1MDV07203-YN:

Issued: July 2007

Version A

NI 40/41

Numerical Three phase Over current

and Earth Fault Relay

Data subject to change without notice

Contents

Sr. Description PageNo. No.

1 About this manual 3

2 The use of the relay 3

3 Feature 3

4 application 4

5 Brief description of operation 4

6 Connection diagram 6

7 Power supply module and output relay card 10

8 HMI features 11

9 Menu systems 14

10 Main Menu 14

11 Group menu, subgroup menu and Parameter menu. 14

12 Measurements 15

13 Recorded data 17

14 Settings 22

15 Configuration 27

16 Time current characteristics 32

17 Technical Data 37

18 Maintenance & Repair 41

19 Internal relay failure 41

20 Dimensions and mounting 41

21 Ordering Details 42

2

3

1 About this manual

This manual provides information on the protection relay NI 40/41 and its applications, focusing on giving a technical description of the relay. The manual also provides basic information on the protection relay NI 40/41 and presents detailed instructions on how to use the Human-Machine Interface (HMI) of the relay, also known as the Man-Machine Interface (MMI).

2 The use of the relay

NI 40/41 is a versatile protection relay mainly designed to protect incoming and outgoing feeders in a wide range of feeder applications. NI 40/41 is based on a microprocessor environment. A self supervision system continuously monitors the operation of the relay. The HMI has a Liquid Crystal Display (LCD) which makes the local use of the relay

3 Features

Protection functions ANSI Code MODEL

NI40 NI41

Three-phase over current protection 51 X X

low-set stage (IDMT or DT)

Three-phase over current 50 X

protection, high -set stage (DT)

Earth fault protection, low-set 51N X X

stage (IDMT or DT)

Earth fault protection, 50N X

high-set stage (DT)

Facility of site selection of IDMT curves for low set stage X X

Four standard IDMT curves (NI, VI, EI, LI) as per IEC standard. X X

Wide and accurate numerical settings with perfect long time stability. X X

Measurement, Monitoring and Recording Function

Measuring of 3 Phase current in primary or secondary terms X X

Measurement of Neutral current in primary or secondary terms. X X

Latest Five fault data recording

Extensive relay internal self supervision monitoring relay hardware and software. X X

Trip lockout function X X

Display and Indications

16 x 2 Alpha numeric LCD display with backlit X X

Aux. supply on, Fault alarm / trip, Internal Relay Failure indication LED's X X

Display of fault cause indication X X

Inputs and Outputs

Four accurate current inputs X X

Normally open heavy duty output contacts X X

Two change over signaling output contacts X X

Freely configurable output contacts X X

Dedicated output contact for relay internal self supervision X X

Low burden on current transformer X X

Relay Design

Relay case with a degree of protection according to IP54 X X

Design confirming to requirements of IEC 60255 X X

Design immune to any kind of electromagnetic interference X X

Dimensions: 196 (H) x 166 (W). Depth behind panel only 158 mm. X X

4

4 Application

This composite relay facilitates combined three phase over current and neutral current relay functions

for use with selective short-circuit and time-over current protection of distribution feeders. It can also be

applied to feeder earth fault protection in solidly earthed, resistance earthed and isolated neutral

networks.

As multi-function solutions, these relays can be flexibly adapted to different kind of incoming and

outgoing feeders in varying substation environments. The NI 40/41 series of relays can be used for

protection of feeders of utility and industrial applications.

With its compact size and unique technical features, NI 40/41 is an ideal relay for retrofit, small switchgear and switchgear with limited space. A small mounting depth makes it possible to install the relay in places where space is money and every millimeter counts.

5 Brief description of operation

In addition to its comprehensive protection functions, the relay provides additional features such as

measurement data in primary value, RMS value in terms of In, fault data recording, fault indications etc.

LCD display and three front LEDs enable fast fault indication. The fault recorded data helps user for

quick fault diagnostics and analysis. The relay also has freely configurable output relays for tripping and

signaling. These value-added features make NI 40 / 41 a product beyond compare.

The combined over current and earth-fault relay is a secondary relay to be connected to the current

transformers of the object to be protected. The three phase over current unit and the earth-fault unit

continuously measure the phase currents and the neutral current of the protected object. On detection of

a fault, the relay trips the circuit breaker, provides alarm, records fault data etc. in accordance with the

application and the configured relay functions.

When the phase current exceeds the set start current of the low-set stage I>, and when the set operate

time at definite time elapses or the calculated operate time at inverse time operation elapses, the over

current unit operates.

In the same way, the high-set stage I>> of the over current unit ( for NI 41 ) operates and delivers a trip

signal when the set start current exceeds and the set operate time elapses. When the earth-fault current

exceeds the set start current of the low-set stage Io>, and the set operate time at definite time operation

elapses or the calculated operate time at inverse time operation elapses, the earth-fault unit operates. In

the same way the highset stage Io>> of the earth fault unit ( for NI 41 ) operates and delivers a trip signal

when the set start current exceeds and the set operate time elapses.

The low-set stage of the over current unit and the low-set stage of the earth-fault unit may be given

definite time or inverse definite minimum time (IDMT) characteristic. When the IDMT characteristic is

chosen, four time / current curves are available that comply with BS 142:1962 and IEC 255 standards

and are named "Normal inverse", "Very inverse", “Extremely inverse” and "Long-time inverse".

By appropriate configuration of the output relay matrix, the trip signals of the over current and earth fault

units are obtained as contact functions.

Figure 1: Protection function of Three phase over current and earth fault relay Type NI 40

Figure 2: Protection function of Three phase over current and earth fault relay Type NI 41

THREE PHASE INVERSE TIME OR DEFINITE TIME LOW SET OVER CURRENT PROTECTION

51

THREE PHASE INVERSE TIMEOR DEFINITE TIME LOW SET EARTH FAULT PROTECTION

51N

THREE PHASE INVERSE TIME OR DEFINITE TIME LOW SET OVER CURRENT PROTECTION

51

THREE PHASE INSTANTANEOUS OR DEFINITE TIME HIGH SET OVER CURRENT PROTECTION

50

THREE PHASE INSTANTANEOUS OR DEFINITE TIME HIGH SET EARTH FAULT PROTECTION

THREE PHASE INVERSE TIMEOR DEFINITE TIME LOW SET EARTH FAULT PROTECTION

51N

50N

IL1

IL2

IL3

Io IRF

TRIP

SIGNAL 1

SIGNAL 2

5

IL1

IL2

IL3

Io IRF

TRIP

SIGNAL 1

SIGNAL 2

6 Connection diagram

Figure 3 Connection diagram for three phase Numerical overcurrent and earth fault relaytype NI 40/41 with core balance CT for earth fault.

6

IRF

INT

ER

NA

L R

ELA

Y F

AIL

UR

E

Connection diagram

Figure 4 Connection diagram for three phase Numerical overcurrent and earth fault relay type NI 40/41 with residual connection of CT’s for earth fault.

7

Uaux Auxiliary voltage

Tr, S1, S2, IRF Output relays

IRF Self-supervision (Internal relay failure)

TRIP Trip output relay

SIGNAL 1 Signal on operation of the overcurrent / Earth fault unit

SIGNAL 2 Signal on operation of the overcurrent / Earth fault unit

T1 Power On indication

T2 IRF indication

T3 Start / Trip Indication

Figure 5 Terminal arrangement of Numerical three phase over current and earth fault relay Type NI 40/41

8

Signal Diagram

The energizing currents of the over current unit

are connected to terminals R1-R2, Y1-Y2 & B1-

B2

The relay can also be used in single-phase or

two-phase applications simply by leaving one

or two energizing inputs unoccupied.

The energizing current for the earth-fault unit is

connected to terminals E1-E2.

The auxiliary supply voltage of the relay is

connected to terminals 14-16. At d.c. supply the

positive lead is connected to terminal 16. The

level of the voltage to be applied to the terminals

depends on the type of power supply module .

Available levels are 18-80v DC or 80-265v

AC/DC. For further details earth see the

description of the power supply module. The

permitted auxiliary voltage range of the relay is

marked on the relay front panel.

Output relay Tr is a heavy-duty trip relay

capable of controlling most circuit breakers.

The operate signals of the different protection

stages are routed to the trip relay by selecting

relay configuration inside the main menu of the

relay and routing the desired relay for that

protection function.

On delivery from the factory all the protection

stages are routed to the trip relay. A latching of

the output relay Tr can be selected by setting

the configuration of TRIP as HR (Hand Reset).

Output relays S1 and S2 can be used for

signaling on operation of the relay module. The

signals to be routed to the output relays S1 and

S2 is carried out by selecting relay configuration

submenu in Configuration menu and then

routing over current or earth fault for desired

signaling relays S1& S2

Both signaling relays, S1 & S2 are configured

for signaling on operation of the over current

unit and earth fault unit which is the default

setting of the relay on delivery from the factory.

Output relay IRF functions as output relay for

the self-supervision system of the protection

relay. The relay IRF is energized under normal

operating conditions and contact gap 27-28 is

closed. If a fault is detected by the self-

supervision system, or on loss of auxiliary

supply, the output relay drops off and the NO

contact 28-29 closes.

Figure 6 The figure below schematically illustrates how the trip and control signals can be configured to obtain required protection function.

9

Signal IL1, IL2, IL3

Abbreviation Io

Tr

S1

S2

IRF

Energizing current of phase L1, L2 & L3

Neutral Current (Residual Current)

Trip relay

Signal Relay 1

Signal Relay 2

Internal relay Failure

7. Power Supply Module and Output relay Card

To be able to operate the relay needs a secured

auxiliary voltage supply. The power supply

module forms the voltages required by the

protection relay cards and the auxiliary relays.

The power supply module contains the power

supply unit and the control circuits of the output

relays. Output relay card contains trip and

signal output relays.

The primary side of the power supply module is

protected with a fuse, F1, located on the PCB of

the module. The fuse size is 1 A (slow).

The power supply unit is a pulse-width

modulated (PWM) dc/dc converter with

galvanically isolated primary and secondary

sides. It forms the dc secondary voltages

required by the protection relay module; i.e.

+24 V, + 12 V and +8 V. The output voltages +12

V and +24 V are stabilized in the power supply

module, while the +5 V & + 3.3 V required by the

processor card are stabilized by linear power

supply on it.

A green LED indicator POWER ON on the

system front panel is lit when the power supply

module is in operation. The supervision of the

voltages supplying the electronics is located in

the power supply module. If a secondary

voltage differs too much from its rated value, a

self-supervision alarm will be generated. An

alarm is also issued on loss of auxiliary supply.

There are two versions of power supply

modules available. For both types, the

secondary sides and the relay driver circuits are

identical, but the input voltage ranges differ.

Insulation test voltage between the primary and

secondary side and the protective earth

2 kV, 50 Hz, 1 min

Rated power P 5Wn

Voltage ranges of the power supply modules :

1. U = 80...265 V dc/acaux

2. U = 18...80 V dcaux

The power supply module for 80...265v can be

fed from either an ac source of a dc source. The

18...80V power supply module is designed for

dc supply only. The permitted auxiliary voltage

range of the relay is marked on the relay system

front panel.

10