numerical transformer protection relay terminal-csc326

Dif

pro

Res

Ov

Transformer Protection Equipment

1

CSC-326 Numerical Transformer Protection Equipment

Fig.1 CSC-326 Numerical Transformer Protection Equipment

Application

The CSC-326 is numerical reliable high-speed protection equipment, which can be used

for small, medium and large power transformers. The CSC-326 includes all necessary

protection functions for transformers. It integrates instantaneous and percent differential

protection, restricted earth fault protection, overflux protection, thermal overload protection,

overcurrent protection and impedance protection etc, along with the entire suite of current,

voltage protection functions in one easily configurable economical package.

The integrated functions supply the user a high flexibility so that adjustments can easily

be made to select protection functions. CSC-326A is applied to two-winding transformer,

CSC-326B is applied to three-winding transformer. Typical functions and arrangement for

CSC-326 series are shown in table 1.

Table 1 Typical Functions and Arrangement for CSC-326 Series Equipment

Type Functions and arrangement

CSC-326A CSC-326B

Main protection

Instantaneous differential protection √ √

Inrush inhibit with 2nd harmonic

Fuzzy recognition of inrush based on waveform

selective selective ferential

tection Overflux inhibit √ √

tricted earth fault protection for HV √ √

erflux (definite and inverse ) for HV √ √


2

Restricted earth fault protection for MV Χ √

Overflux (definite and inverse ) for MV Χ √

Restricted earth fault protection for LV configurable Χ Backup protection in HVhigh voltage side

Thermal overload protection √ √

IDMTL overcurrent protection √ √

IDMTL earth fault protection √ √

Phase-to-phase distance protection configurable configurable

Phase-to-earth distance protection configurable configurable Definite overcurrent protection(with selective direction) √ √

Neutral current protection (with selective direction) √ √

Neutral displacement protection √ configurable Pole discordance protection √ √

Overload protection √ √

Overcurrent blocking voltage regulation protection √ √

Backup protection in MV(middle voltage) side Only for three-winding

transformer

Thermal overload protection Χ √

IDMTL overcurrent protection Χ √

IDMTL earth fault protection Χ √

Phase-to-phase distance protection Χ configurable

Phase-to-earth distance protection Χ configurable Definite overcurrent protection(with selective direction) Χ √

Neutral current protection (with selective direction) Χ √

Neutral displacement protection Χ √

Switching onto fault protection Χ √

Pole discordance protection Χ configurable

Overload protection Χ √

Overcurrent blocking voltage regulation protection Χ √

Backup protection in LV(low voltage) side

IDMTL overcurrent protection √ √

IDMTL earth fault protection √ √

Definite overcurrent protection(with selective direction) √ √

Switching onto fault protection √ √

Zero sequence overvoltage protection √ √

Overload protection √ √

Overload for LV winding (inside delta) configurable configurable Common winding protection Only for auto-transformer

IDMTL Earth fault protection Χ configurable

Features

Short-circuit protection for two-winding and three-winding transformers with

integrated ratio and vector group compensation. Restraint during inrush, overflux and CT


3

saturation are integrated.

Both fuzzy recognition of inrush conditions based on the waveform and 2nd harmonic

ratio restraint schemes are selective for user.

A new method of calculating restraining current using the maximum current and the

sum of the other vector currents as two equivalent parts is applied.

CT failure and VT fuse failure are integrated for supervision.

Restricted earth fault protection is integrated for all star windings.

Definite and inverse time overflux protection are integrated.

Incorporates the latest high-powered fourth generation hardware system with 32 bit

DSP-MCU combined chip technology, which gives computational intensity and system

control efficiency in a single chip.

All setting parameters can be input via either the integrated operator and display

panel or a personal computer(PC). The parameters are written into non-volatile memory so

that the setting values remain secure even during interruption of the supply voltage. There

are 4 separate setting groups stored in the CSC-326’s memory.

All important hardware and software components are continuously monitored,

irregularities in hardware and program sequence are detected and alarmed. This improves

the security and availability of the protection system significantly.

Current, voltage, differential and restraint currents, 2nd and 5th harmonic differential

currents etc can be monitored conveniently through LCD (Liquid crystal display).

The influence of harmonics, higher frequency transients, DC transient components

and CT saturation effects are extensively suppressed.

The equipment is equipped with 1 serial interface. The serial interface is suitable for

connecting a PC. The PC based software CSPC can be used for convenient and transparent

setting, recording disturbance and evaluation as well as commissioning.

2 RS485 and 2 Ethernet interfaces (or 2 electric or fiber Ethernet interfaces, selective)

are equipped on the rear board. It is convenient to connect to a substation automation

system or to a protection data master unit. These ports support IEC 61850 & IEC

60870-5-103.

6 shortcut keys on the front panel, in which 4 keys for printing all kinds of messages,

2 keys for switching the setting storage groups.

The equipment supplies detailed data for the analyzing disturbances as well as for

checking states during operation. Disturbance event and operation indications memories are

safeguarded against supply voltage failure.

Outputs, display of indication. Indication (alarm) relays & LEDs meets user


4

requirements. The storable LED displays are secured against DC power supply failure..

Functions

The following protection functions are integrated:

Differential protection (Including: Treble slope percent differential protection;

instantaneous differential protection and inrush inhibit and overflux inhibit etc.)

Restricted earth fault protection for HV and MV sides

Overflux protection for HV and MV sides

Definite time overcurrent protection for HV, MV and LV sides (with selective direction)

Distance protection for HV, MV sides (Including phase to phase distance protection and

phase to earth protection)

Neutral current protection for HV and MV sides (with selective direction)

Neutral displacement protection for HV and MV sides

Pole discordance protection for HV and MV sides

Switching onto fault protection for MV and LV sides

Overload protection for HV, MV, LV sides and LV winding inside delta

Thermal overload protection for HV side

Overcurrent blocking voltage regulation protection for HV and MV sides

Zero sequence overvoltage protection for LV side

IDMTL overcurrent protection for HV, MV and LV sides

IDMTL earth fault protection for HV, MV and LV sides

Construction

The enclosure for equipment is 19 inches in width and 4U in height according to IEC

60297-3.

The equipment is flush mounted with panel cutout.

The equipment for cabinet mounting has rear connection terminals.

The front panel of the equipment is unclosed from the top of the equipment. LCD, LEDs and

keys are mounted on the panel. There is a serial interface on the panel.

Draw-out modules for serviceability are fixed by lock component.

The modules can be combined through the bus on the rear board. Both the equipment

and the other system can be combined through the rear interfaces.


5

Detail See Fig 13, it shows the flush-mounted enclosure of CSC-326 with panel cutout.

Differential protection (ANSI-87T)

Differential protection is the primary protection for transformers. The main features are

as follows:

Automatic ratio and vector group compensation

CSC-326 performs automatic ratio and phase angle compensation for all possible vector

groups. This simplifies application of the relay as all the CT could be connected in wye (Star

configuration).

Treble slope percent differential protection

Percent differential protection uses a treble-slope dual break-point operating

characteristic with magnetizing inrush and overflux inhibits integrated.

IR1

ID>

Idiff

Ires

Restraint current

Diff

eren

tial c

urre

nt

Slope 3

Slope 2

Slope 1

Trip area

block area

ID>>Fast trip area

IR2

Fig2. Differential protection characteristics for transformers

Selective inrush inhibit schemes

CSC-326 provided 2 schemes to cope with the magnetizing inrush conditions. The first

scheme is a ratio between the second harmonic and the fundamental frequency component.

The second scheme is fuzzy recognition of inrush conditions based on the waveform. The

two schemes are convenient for user to select.

Overflux inhibit

Traditional 5th harmonic based overflux inhibit is integrated with the percent differential

protection.

Instantaneous differential characteristics

An instantaneous (unrestrained) differential current protection is provided for fast

tripping on severe internal faults.

CT failure supervision and CT saturation recognition


6

Restricted earth fault protection (ANSI 87TN)

The restricted earth-fault protection permits high sensitivity to single-pole faults. The

neutral current and the residual currents are compared. The typical connection examples

are shown in Fig3. and Fig4.

Zero-sequence currents are calculated on the basis of the phase currents. Ratio

compensation and CT failure recognition etc are integrated in the protection.

A

B

C

Side 1A

B

C

Side 2

CSC-326 013I&

Fig3. Restricted earth fault protection on an earthed transformer winding

A

B

C

CSC-326

A

B

C

013I&

2.AI&

2.BI&

2.CI&

3.AI&

3.BI&

3.CI&

Fig4. Typical connection for restricted earth fault protection on autotransformer

The differential and restraint quantity is fitted into the restraint characteristic (See Fig5).

A number of monitoring processes avoid unwanted operation in the event of external

short-circuits. In the case of a sensitive setting, multiple measurements ensure the

necessary reliability.


7

0dI

0rI

0DI

0BI

DK0

Trip area

block area

u/f

N0

N1

N2

N3

N4

N5

N6

N7

T7 t (s)T6 T5 T4 T3 T2 T1 T0

Pick

up th

resh

old

u/f

Thermal trip stage

overexcitation trip stage

Fig5. Characteristic of restricted earth-fault protection Fig6. Inverse overflux characteristic

Overflux protection (Volt/Hertz) (ANSI-24)

The overflux protection serves for detection of an unpermissible high induction in

transformers, which leads to a thermal overloading. This may occur when starting up,

shutting down under full load, with weak systems or under isolated operation. The inverse

characteristic can be set via seven points derived from the manufacturer data (see Fig.6).In

addition, a definite-time alarm stage and a definite-time trip stage can be used.

For calculation of the voltage/frequency ratio, frequency and also the maximum of the

three phase voltages are used. The frequency range from 15Hz to 65Hz can be monitored in

this way.

Thermal overload protection (ANSI 49)

This feature provides thermal overload protection for cables and transformers within

the relay zone. Thermal protection is used to safeguard against system abnormalities rather

than faults (abnormally heavy loads, etc). The temperature of the protected object is not

measured directly. Instead, thermal overload conditions are detected by calculating the

average of the currents flowing in the 3 phase conductors. This average value is fed to the

thermal algorithms.

The average current rise above a defined overload setting for a defined operating time

T, the system will be tripped to prevent damage. The formula for thermal overload is as

follow:

−×=

22

2

)(ln

θτ

IIIT

T = Thermal trip time

I = Equivalent Thermal current

Iθ = RMS Thermal current

ζ = Thermal time constant of transformer


8

Additionally, alarm will be given if:

1. The average current exceeds the thermal overload alarm level. If left at this level

the current would result in a thermal overload trip.

2. The thermal state of the system exceeds a specified percentage of the protected

object’s thermal capacity alarm.

3. The step rise in the thermal state of the system is greater than a specified

percentage of the object’s thermal capacity.

The thermal overload is usual to be allocated to the source side winding; it also can be

applied to either winding as desired.

Distance protection (ANSI21)

Both phase to phase distance protection and phase to earth distance protection are

provided in CSC-326. This fast short-circuit protection protects the transformer and is a

backup protection for the power system. Phase-to-phase distance protection has two

settable impedance stages; Phase-to-earth distance protection has one stage.

In order to avoid the maloperation of the distance protection, it is blocked when VT is fail.

The distance characteristic is a mho characteristic with offset (see Fig.7).

RZ

XZ*NZ

XZ

RZ*NZ

R

X

Fig7. Tripping characteristics of distance protection

Definite overcurrent protection (ANSI50 51 67)

This protection is a backup protection for the transformer and the power system. The

protection comprises 2 stages I>. The integrated direction function can be applied to the

overcurrent protection via binary settings.

Neutral current protection

This protection function is a backup protection for the transformer and the power

system. The protection comprises 2 stages I0>. The integrated direction function can be

applied to the neutral current protection via binary settings. The earth currents are

measured directly at the star-point CT or calculated by the three phase currents.

IDMTL Overcurrent protection (51 IDMTL)


9

Both IEC and ANSI pick-up curves are provided for IDMTL Overcurrent protection. They

are selective for user.

IDMTL Earth fault protection (51N IDMTL)

Both IEC and ANSI pick-up curves are provided for IDMTL Earth fault protection. They

are selected for user.

Neutral displacement protection (59N)

This protection is often used for the transformer which the neutral is not earthed. The

protection comprises 2 stage 3U0>, including one alarm stage and one trip stage. For HV

(High Voltage ) and MV (Middle Voltage) sides of the transformer, the voltage is measured

directly at the open delta VT. For LV (Low Voltage ) side , the voltage is calculated by three

phase voltages.

Pole discordance protection

Pole discordance protection evaluates current components and the circuit-breaker

auxiliary contact. The components include negative sequence current I2> and zero

sequence current 3I0>. It can be started by external via digital input.

Switching onto fault protection

This protection is to protect the bus in MV (Middle Voltage) or LV (Low Voltage) sides

when the corresponding circuit breaker is switched into a fault bus. Switching onto fault

protection evaluates a maximum current and the circuit-breaker auxiliary contact.

Other protections

The CSC-326 also provide other auxiliary protections. Including, overload protection,

overcurrent blocking voltage regulation protection. The overload protection is to protect all sides

of windings of transformer continuous overload currents. The protection only comprises a

definite time alarm stage.

External signals

For recording and processing of external trip information there are some digital inputs.

They are provided for information from auxiliary protection device.

Fault and event recorder

In a protection unit, depending on the parameterization, the instantaneous values are

used. The maximum period of a disturbance recording depends on the memory and

sampling frequency. Within the buffer several disturbance records (up to 8) can be stored


10

consecutively. The number is dependent on the parameterization and nature of the fault

event data record.

The possibility to set a pre- and post trigger time and the triggering event (disturbance

recording start with activation or trip) permits flexible adaptation to the different

requirements.

The disturbance record data can be transferred either to the substation automation

system or to a PC, and evaluated depending on the user preference.

On-load measurement

The on-load measured values generated in the unit such as current, voltage, phase

angle, differential current, restraint current,2nd harmonic current as well as 5th harmonic

current can be displayed at the LCD or by means of a PC.

Trip matrix/trip circuits

The unit is equipped with some trip matrix settings, which can be set via the operator

panel.


11

Technical data

Input circuits Rated current IN Rated voltage UN

Rated frequency fN Thermal overload capability In voltage circuit, continuous In current circuit, continuous

≤ 10s 1s Power consumption

In voltage circuit at UN=110V In current circuit at IN = 1A

at IN = 5A

1 or 5A 63.5V or 110V AC 50Hz 1.2×UN AC 2×IN

10×IN 70×IN less than 0.5VA less than 1VA less than 0.5VA

DC voltage supply Rated auxiliary voltage Uaux

Permissible tolerance at rated auxiliary voltage Power consumption

at energized state at quiescent state

220V DC; 110V DC -30% to +14% max. 50W max. 30W

Pick-up tolerances under rated conditions

Current values Voltage values distance values Time values

Less than 3% of set value Less than 3% of set value Less than 3% of set value Less than 20ms

Digital inputs Digital inputs for 24V DC voltage Current consumption for each inputDigital inputs for 220V/110 DC voltage Current consumption for each input

12, can be expanded 26; 2mA5mA 12, can be expanded 26; 1mA3mA

Contacts

Potential-free trip/command contacts Switching capacity make Break Permissible current ,Continuous 0.5s Switching voltage Indication contacts Switching capacity make/break Permissible current Switching voltage

32 contacts, expandable 1250VA(AC), 150W(DC) 5A 30A 250V DC 16 1250VA(AC), 150W(DC) 5A 250V DC

Mechanical structure

Housing / dimensions Weight approx. Type of terminal Protection class

19 inches, 4U 8kg Harting module terminal & circuit terminal in special design IP20

Displays LED displays unit front 8 Standards IEC 60255 series & China standards

(GB,DL)

Insulation tests Dielectric voltage test Impulse voltage test

IEC 60255-5,2kV IEC 60255-5,5kV

Immunity tests High frequency test Electrostatic discharges

IEC 60255-22-1, add.100kHz according to CHINA standard, class III


12

electromagnetic field Fast transient disturbances Power frequency magnetic field Conducted disturbance of RF, amplitude modulated

IEC 60255-22-2,class IV IEC 60255-22-3,10V/m IEC 60255-22-4, class IV(8kV) IEC 61000-4-8,class III IEC 60255-22-6,10V/m

Emission tests Class according with IEC IEC 60255-25 Climatic conditions Permissible ambient temperature

during service during storage during transport Humidity class

-10ºC~+55ºC -10ºC+40ºC -25ºC~+70ºC <75%

Mechanical stress Permissible mechanical stress during service during transport

IEC 60255-21-1,class I IEC 60255-21-2,class I

communication Front port RS-232; CSPC software for interrogation of the relays, testing etc. from a PC/Laptop

Rear Port RS-485 & 2 Ethernet ports-Communication with the substation automation system. Supports IEC 61850 & IEC 60870-5-103

Differential protection Setting ranges High-current stage ID>>

Differential current ID> Inrush stabilization ratio (2nd harmonic) PU & DO Times Pickup time (At 2 times of set value ID>) Pickup time (At 1.5 times of set value ID>>) Drop-off time Drop-off ratio Tolerances Pickup characteristic Inrush Restraint Additional Delay Times Others 5th Harmonic stabilization ratio percentage of slop 1 percentage of slop 3 restrain current point 1

restrain current point 2

2~100A 0.3Ie~1.0 Ie (Ie: nominal current of the reference side ) 0.05~0.30 less than 30ms less than 20ms approx. 20ms approx. 0.7 ±5% of set value or ±0.02IN ±5% of set value ±1% of set value or 10ms 0.35 fixed 0.2 fixed 0.7 fixed 0.2Ie(Ie: nominal current of the reference side ),fixed 5 Ie fixed

Restricted earth fault protection

Setting ranges Differential current I0D> Percent restrained K0D> PU & DO Times At 2 times of set value Drop-off time Drop-off ratio Tolerance Pickup characteristic

0.3Ie~1.0 Ie(Ie: nominal current of the reference side ) 0.3~0.7 less than 30ms approx. 40ms approx. 0.7 ±5% of set value or ±0.02IN


13

Additional time delay less than 30ms Overflux protection (Definite-time and inverse-time Overflux )

Setting Ranges Reference voltage UN

Ratio( >N

N

ffUU

//

):

Time Delay T Pair of Values for Characteristic of

U/f PU & DO Times At 1.2 times of set value Drop-off time I> Drop-off ratio Tolerance

Ratio( >N

N

ffUU

//

):

Time delays for definite Time delays for Inverse

40~100V 1.00~1.40 0.1s~9999.0s 1.10/1.15/1.20/1.25/1.30 /1.35/1.40 less than 40ms approx. 40ms Not less than 0.96 ±2.5% of the set value less than 40ms less than 40ms or ±3% of set value

IDMTL Overcurrent protection (according to different parameter setting , IEC AND ANSI IDMTL Curves can be got )

Setting ranges Current Time constant Themal capacity factor A Curve Character Power P Supplyment constant B Tolerance Current pickup I> Time delays Drop-off ratio I>

0.1×IN to 20×IN

0.025 to 2s 0.1 to 130 0 to 2 0 to 1 ±3% of set value or ±0.02IN not less than 40ms not less than 0.95

Distance protection (including phase to

phase distance / phase to earth distance)

Setting ranges Resistance(Rz )

Reactance(Xz ) Time delay T PU & DO Times:

Shortest tripping time At 0.7 times of set value

Drop-off time Starting element Current I2> Drop-off ratio Tolerance RZ< XZ< Time delays

IN=1A :0.5 to 125Ω; IN=5A :0.1 to 25Ω; IN=1A :0.5 to 125Ω; IN=5A :0.1 to 25Ω; 0.1 to 20s approx. 0.1s less than 40ms approx.40ms 0.2IN 1.05 ±3% of set value or ±0.1Ω not more than 40ms

Definite-time overcurrent protection (with selective direction )

Setting ranges Current I> Time delay T The sensitive angle of directional element PU & DO Times At 1.2 times of set value Drop-off time I>

0.1×IN to 20×IN

0.1 to 20s -45° less than 40ms approx. 40ms


14

Tolerance Current pickup I> Angle of the directional element Time delays Drop-off ratio

I>, Directional element:

Voltage threshold Angle of the directional element

±3% of set value or ±0.02IN ±2° not more than 40ms not more than 0.90 1V 170°±2°

Neutral current protection (with selective direction)

Setting ranges Current 3I0> Time delay T PU & DO Times At 1.2 times of set value Drop-off time 3I0> Tolerance Current pickup 3I0> Angle of the directional element Time delaysDrop-off ratio

3I0> Directional element: Zero voltage threshold Angle of the directional element

0.1×IN to 20×IN

0.1 to 20s less than 40ms approx. 40ms ±3% of set value or ±0.02IN ±2° not more than 40ms approx. 0.9 0.5V 160°±2°

IDMTL Earth fault(neutral current) protection(according to different parameter setting , IEC AND ANSI IDMTL Curves can be got )

Setting ranges Current 3I0> Time constant Themal capacity factor A Curve Character Power P Supplyment constant B Tolerance Current pickup 3I0> Time delays Drop-off ratio 3I0>

0.1×IN to 20×IN

0.025 to 2s 0.1 to 130 0 to 2 0 to 1 ±3% of set value or ±0.02IN not less than 40ms not less than 0.95

Neutral dispalcement protection (for HV and MV side of the transformer)

Setting ranges Voltage 3U0> Time delay T PU & DO Times At 1.2 times of set value Drop-off time 3U0> Tolerance Voltage pickup 3U0> Time delaysDrop-off ratio 3U0>

160 to 300V 0.1 to 20s less than 40ms approx. 40ms ±5% of set value or ±0.1V not more than 40ms approx. 0.9

Pole discordance protection

Setting ranges Current 3I0> Current I2> Time delay T PU & DO Times At 1.2 times of set value Drop-off time 3I0>, I2> Tolerance Current pickup 3I0>, I2> Time delays

0.1×IN to 20×IN

0.1×IN to 20×IN

0.1 to 20s less than 40ms approx. 40ms ±3% of set value or ±0.02IN not more than 40ms


15

Drop-off ratio 3I0>, I2>

approx. 0.9

Switching onto fault protection

Setting ranges Current I> Time delay T PU & DO Times At 1.2 times of set value Drop-off time I> Tolerance Current pickup I> Time delaysDrop-off ratio

I>

0.1×IN to 20×IN

0.1 to 20s less than 40ms approx. 40ms ±3% of set value or ±0.02IN not more than 40ms approx. 0.9

Thermal overload protection

Setting ranges Current I> Thermal time constant

Reset ratio Tolerance Current I> Time delays

0.1×IN to 20×IN

1 to 1000mins not less than 0.95 ±3% of set value or ±0.02IN approx. 40ms

Other protection ( Overload protection; overcurrent blocking voltage regulation protection)

Setting ranges Current I> Delay times T

Reset ratio Tolerance Current I> Time delays

0.1×IN to 20×IN

0.1 to 20s not less than 0.90 ±3% of set value or ±0.02IN approx. 40ms

On-load measurement

Display of values for current for voltage for differential current for 2nd harmonic differential current for 5th harmonic differential current for power supply

IHV1A,IHV1B,IHV1C,IHV2A,IHV2B, IHV2C,IMA,IMB,IMC,ILVA,ILVB,and ILVC etc UHVA, UHVB, UHVC,UMVA,UMVB, UMVC, ULVA, ULVB and ULVC etc DI1A,DI1B,DI1C DI2A,DI2B,DI2C DI5A,DI5B,DI5C DC+,DC-

Fault recording Instantaneous values (approx. every 0.833ms at 50Hz) 2 records of max. 5 secs duration (adjustable pre & post fault duration)

IHV1A,IHV1B,IHV1C,IHV2A,IHV2B,IHV2C, IMA,IMB,IMC,ILVA,ILVB,ILVC, UHVA,UHVB,UHVC,UMVA,UMVB, UMVC,ULVA, ULVB,ULVC etc


16

Selection and ordering data

CSC-326 Order No.

CSC-326 Numerical multifunction Transformer protection equipment

ADifferent protected object for two windings transformer for three windings transformer

15

Rated current for high voltage side1A5A

15

15

Rated current for middle voltage side1A5ARated current for low voltage side1A5A

1

2

Rated auxiliary voltage110V DC220V DC

KW

Master module type,different hardware087125

0

12

Lonworks interface (slave mode)12

320

Electric internet interface on Master module320

20

Fiber internet interface on Master module20

12

RS485 interface on Master module12

B

Lonworks interface (master mode)0 0

Operating software CSPC

CSPC Version V1.00E for windows,full version for 10 PC’ s and update for 3 years

English 0SF.******

Documentation

Catalog:CSC-326 Numerical transformer protection equipment (V1.00E)Manual:CSC-326 Numerical transformer protection equipment(V1.00E)

0SF.******English

0SF.******


17

Connection diagram

Figure 8 and Figure 9 illustrate the recommended standard connection for two-winding

transformers. Figure 10 and Figure 11 illustrate the recommended standard connection for

three-winding transformers. Figure 12 illustrates connection for the CT inside delta.

Differential protection embraces protection of the high voltage side and low voltage side

of the transformer cable. The permissible cable length and the CT design (permissible load)

are mutually dependent. Recalculation is advisable as for lengths of more than 100m.

Typical connection 1 for two-winding transformer

2a

3a

2b

3b

IHVA1a 1b

7a 7b

8a 8bINBKHV

IHVB

IHVC

2a

3a

2b

3b

ILVA 1a 1b

ILVB

ILVC

A B C

A B C

UHVA 11a

10a

10b

11b

9a

9b

UHVB

UHVC

UHVN

UHV0

UHV0N

ULVA 11a

10a

10b

11b

ULVB

ULVC

ULVN

AI1

AI2

IREFHV

Transformermodule

Transformermodule


18

Fig 8 Typical connection example for two-winding transformer

Typical connection 2 for two-winding transformer

2a

3a

2b

3b

IHVA1a 1b

IHVB

IHVC

2a

3a

2b

3b

ILVA 1a 1b

ILVB

ILVC

A B C

A B C

UHVA 11a

10a

10b

11b

9a

9b

UHVB

UHVC

UHVN

UHV0

UHV0N

ULVA 11a

10a

10b

11b

ULVB

ULVC

ULVN

AI1

AI2Transformermodule

Transformermodule

4a 4b

5a 5bINBKLV

IREFLV

Fig 9 Another typical connection example for two-winding transformer


19

Typical connection for three-winding transformer


20

2a

3a

2b

3b

IHV1A 1a 1b

IHV1B

IHV1C

A B C

A B C

UHVA 11a

10a

10b

11b

9a

9b

UHVB

UHVC

UHVN

UHV0

UHV0N

ULVA 11a

10a

10b

11b

ULVB

ULVC

ULVN

AI1


Transformermodule


2a

3a

2b

3b

1a 1bIMVA

IMVB

A B C

IMVC

UMVA11a

10a

10b

11b

9a

9b

UMVB

UMVC

UMVN

UMV0

UMV0N

2a

3a

2b

3b

ILVA 1a 1b

ILVB

ILVC

7a 7b

8a 8b


IREFHV

INBKMV

4b4aIREFMV

5b5a

INBKHV

Fig 10 Typical connection example for three-winding transformer

Typical connection for autotransformer


21

2a

3a

2b

3b

IHV1A 1a 1b

IHV1B

IHV1C

A B C

A B C

UHVA 11a

10a

10b

11b

9a

9b

UHVB

UHVC

UHVN

UHV0

UHV0N

ULVA 11a

10a

10b

11b

ULVB

ULVC

ULVN

AI1


Transformermodule


2a

3a

2b

3b

1a 1bIMVA

IMVB

A B C

IMVC

UMVA11a

10a

10b

11b

9a

9b

UMVB

UMVC

UMVN

UMV0

UMV0N

2a

3a

2b

3b

ILVA 1a 1b

ILVB

ILVC

7a 7b

8a 8b


IREFHV

INBKHV

4a 4b


INBKMV

Fig 11 Typical connection example for autotransformer


22

Typical connection for low CT in Delta winding

5a

6a

5b

6b

ILVWA 4a 4b

ILVWB

ILVWC


2a

3a

2b

3b

ILVA 1a 1b

ILVB

ILVC

A B C

A B C

Fig.12 Typical connection example for low voltage side CT in delta winding


23

Dimension drawings in mm

Dimension drawings for CSC-326 used 19 inch (4U) enclosure for panel flush-mounting

and cabinet mounting.

Fig.13 flush-mounted enclosure of CSC-326 with panel cutout

numerical transformer protection relay terminal-csc326

Documents