7UT61X Transformer Protection

The year of Profitable Growth

Global network of innovation

Module 10B:

Transformer Protection

Power Automation 2

Power Transmission and Distribution

Power AutomationProgress. Its that simple.

FACTS

SITRAM+SiemensTransformerMonitoringSystem forall voltagelevels

Generatortransformer

Systeminterconnectingtransformer

Shunt reactor

Oil-immerseddistribution transformer

GEAFOLcast-resin transformer

Tractiontransformer

HVDC

Systemtransformer

Convertertransformer

Furnacetransformer

Voltageregulator

TLM50+SiemensTransformerLifeManagementProgram

Commissioning and operating aids (4 of 5)
06 BB TLM .ppt01 About us1.pps

Power Automation 3



575-MVA Phase Angle Regulator (PAR)Transformer Set in the 345 kV Station

Power Automation 4



630-kVA Oil-Immersed DistributionTransformers, TUMETIC, TUNORMA

Power Automation 5



Transformer Prices

>40 MVA

10,-US$ pro kVA =>

30MVA = 40.000 kVA *10 US$ = 300.000US$

>200 MVA

8,-US $ pro kVA =>

200 MVA 200.000kVA *8 US$ = 1600.000US$

>1000 MVA

5,-US$ pro kVA =>

1000 MVA 1000.000kVA *5 = 5000.000 US$

Power Automation 6



On-site servicesand repair

SITRAD Condition assessment program

SITRAM+ transformermonitoring system

Traditional heat andvacuum treatment

SIDRY, SMART DRY,SIREC advanced lifeextension programs

TLM50+ Siemens Transformer Life Management Program

Power Automation 7



Transformer Faults

Power Automation 8



The 7UT6 Family

7UT612: for two end protection objects (1/3 x 19 housing 7XP20)

7UT613: for three end protection objects (1/2 x 19 housing 7XP20)

7UT633: for three end protection objects (1/1 x 19 housing 7XP20)

7UT635: for five end protection objects (1/1 x 19 housing 7XP20)

SIPROTEC 4

7UT6 differential protection relay for transformers,

generators, motors and busbars

Power Automation 9



Hardware options

7UT612

7 (7)*

1

---

3

4

1

4 lines

7UT613

11 (6)*

1**

3 / 1

5

8

1

4 lines

7UT633

11 (6)*

1**

3 / 1

21

24

1

Graphic

Device

Current Inputs (normal)

Current Inputs (sensitive)

Voltage Inputs (Uph / UE)

Binary Inputs

Binary Outputs

Life contact

LC Display

7UT635

14 (12)*

2**

---

29

24

1

Graphic

* 1A, 5A, (1A, 5A, 0.1A) changeable (jumper position)

** changeable normal or sensitive (jumper position)

Power Automation 10



Scope of functions and Protection objects

Function ANSI No.

Differential 87T/G/M/L

Restricted Earth fault 87 N

Overcurrent-time, phases 50/51

Overcurrent-time, 3I0 50N/51N

Overcurrent-time, earth 50G/51G

Overcurrent-time, single phase

Negative sequence 46

Overload IEC 60255-8 49

Overload IEC 60354 (hot spot) 49

Overexcitation V/Hz 24

Breaker failure 50BF

External temperature monitoring 38

Lockout 86

Measured value supervision

Trip circuit supervision 74TC

Direct coupling

Operational measured values

Protection Objects

Three-phase transformer

Single-phase transformer

Auto-transformer

Generator / Motor

Busbar, 3-phase (Branch point)

Busbar, 1-phase

Power Automation 11



Cross reference - functions and protected objects

Protection functions ANSI No. Transf.

3-phase

Transf.

1-phase

Auto-

transf.

Gen. /

Motor

Busbar

3-phase

Busbar

1-phase

Differential 87T/G/M/L X X X X X X

Restricted Earth Fault 87 N X X --- X --- ---

Overcurrent-time, phases 50/51 X X X X X ---

Overcurrent-time, 3I0 50N/51N X --- X X X ---

Overcurrent-time, earth 50G/51G X X X X X X

Overcurrent-time, single phase X X X X X X

Negative sequence 46 X --- X X X ---

Overload IEC 60255-8 49 X X X X X ---

Overload IEC 60354 49 X X X X X ---

Overexcitation V/Hz *) 24 X X X X X X

Breaker failure 50 BF X X X X X ---

External temperature monitoring

(thermo-box)

38 X X X X X X

Lockout 86 X X X X X X

Measured value supervision X X X X X X

Trip circuit supervision 74TC X X X X X X

Direct coupling 1 X X X X X X

Direct coupling 2 X X X X X X

Operational measured values X X X X X X

X Function applicable ; --- Function not applicable ; *) only 7UT613 / 633

Power Automation 12



Communication features

Front interface

DIGSI4

WEB Monitor

Service interface (s)

DIGSI4 operation

modem connection

RTD box

Flexibility due to plug in modules

Compatibility to international standards

System interface

IEC60870-5-103

Profibus FMS

Profibus DP

DNP3.0

Modbus ASCII/RTU

Time synchronising

IRIG-B (GPS)

DCF77

RS232/RS485 electrical module

Fibre-optic module

Optical double-ring module

Power Automation 13



Connection Example

direct connection to themain Cts

no matching transformers /no matching connections

numerical vector groupadaptation without zero sequence current correctiondepending of the type ofearthing of the winding.

increased sensitivity by 33%by measuring of the zerosequence current (7UT6) forsingle-pole faults.

1A/5A main Cts adaptationin the relay

permissible ratio Ct nominalcurrent to transformer nominalcurrent up to 1 : 4

IL2M1

IL1M3

IL2M2

IL3M2

IL2M3

IL3M1

IL3M3

IL1M2 IL1M1IX1 IX3

7UT613

M1

M3

M2 side 1side 2

side 3

Surfacemountinghousing

Flush/cubicle-mountinghousing

L1

L2

L3

L1

L2

L3

L1

L2

L3

Power Automation 14



Application: 3-winding transformer YNd5d11 (1 of 4)

M1

400/1A

M2

400/1A

M3 400/1A

M4

8000/1A

M5

3500/1ASide 1

Side 2

Side 3

IL1M1/I1

IL2M1/I2

IL3M1/I3

IL1M2/I4

IL2M2/I5

IL3M2/I6

IL1M3/I7

IL2M3/I8

IL3M3/I9

IL1M4/I10

IL2M4/I11

IL3M4/I12

IL1M5/Ix1

IL2M5/Ix2

IL3M5/Ix3

Ix4

7UT635

M1

M2

M4

M5

M3

200/1A

Power Automation 15



Application: 3-winding transformer YNd5d11 (2 of 4)-Device Configuration and Power System Data 1

7UT635

Power Automation 16



Application: 3-winding transformer YNd5d11 (3 of 4)-continue Power System Data 1

7UT635

Power Automation 17



Application: 3-winding transformer YNd5d11 (4 of 4)-continue Power System Data 1

7UT635

Power Automation 18



Application: Autotransformer with Winding (1 of 2)

7UT613

M1

M2

M3

IL1M2

IL2M2

IL3M2

IL1M1

IL2M1

IL3M1

IL1M3

IL2M3

IL3M3

Side 3Side 1

Side 2

Power Automation 19



Application: Autotransformer with Winding (2 of 2)- Power System Data 1

7UT613

Power Automation 20



Application: Autotransformer with Winding (2 of 2)- Power System Data 1

Power Automation 21



Application: Autotransformer (bank) with (1 of 2)3 Cts at the star point side available

M1

M2

M3

7UT613

Only compensation winding,

no external connection!

Increased sensitivity for

phase to phase- and

phase to ground faults

towards the star point!

Power Automation 22



Application: Autotransformer (bank) with (2 of 2)3 Cts at the neutral side

7UT613

Power Automation 23



Application: Single-phase bus bar (1/2)- Phase selective configuration (1 7UT6 for 1 phase)

7UT612:

7 current-

inputs

7UT613/633:

9 current-

inputs

7UT635:

12 current-

inputs

7UT612

Power Automation 24



Application: Single-phase bus bar (2/2)- Phase selective configuration (1 7UT6 for 1 phase)

2 more Relays

for Phase 2 and 3

are necessary

7UT612

Power Automation 25



Application: Single-phase bus bar (1 of 2)- configuration with Summation Cts

7UT612:

7 current-

inputs 0.1A

7UT613/633:

6 current-

inputs 0.1A

7UT635:

12 current

inputs 0.1A

7UT612

*) Summation CT

4AM5120-3DA00-0AN2: 1/0.1A

4AM5120-4DA00-0AN2: 5/0.1A

7UT612

Power Automation 26



Application: Single-phase bus bar (2 of 2)- configuration with Summation Cts

Not important

in this case

7UT612

Power Automation 27



General Applications (1 of 2)

1 C.B. application withtwo winding transformer

7UT613

7UT633

Three winding transformer1 or 3 phases

7UT613

7UT633

Short lines(2 ends)

7UT612

Short lines(3 ends)

7UT613

7UT633

Two winding transformer1 or 3 phases

7UT612

7UM62

1 C.B. application onHV and LV side with

two winding transformer

7UT635

Power Automation 28



General Applications (2 of 2)

Unit Protection(Overall Differential)

Y

G

3~

7UT635

Generator/Motor longitudinal ortransversal differential protection

7UT612

7UM62

G/M

3~

High-impedanceRestricted Earth Fault Protection

IEE input

of the unit

7UT6xx

Power Automation 29



Differential functions IDiff> and IDiff>>

IDiff> restrained (biased) differential function, IDiff> = f(IRest)

- Ct-saturation detector (add on stabilization) for external faults.

IDiff>> fast unrestrained high current differential function, its setting therefore should be higher then

the maximum possible through flowing current! Example Transformer: IDiff>> > (1/uk)InO

This function will be not blocked by harmonics due to an inrush or Ct-saturation!

The IDiff>> stage evaluates the fundamental wave of the currents as well as the instantaneous values.

- Fundamental wave processing: fast tripping at the set threshold.

- Instantaneous value processing: ensures fast tripping even in case the fundamental wave

of the current is strongly reduced by Ct-saturation. Because of the possible DC offset after fault

inception, the instantaneous value stage operates only above twice the set threshold.

IDiff>>

2IDiff>>

IDiff> IRest

IDiff

IDiff

iDiff

&Trip

IDiff>

1Trip

IDiff>>

Instantaneous

values

fundamental wave:

IDiff = rms(iDiff)50Hz

iRest = i1 + i2rectified mean value:

IRest = iRest

measured valuepre-processing

( vector gr. ,Cts )

side 1i1L

i2Lside 2 iDiff = i1 + i2

Tripping characteristic,saturation detection

iRest IRest

msI / In

O

iDiffIDiff

ms

I / In

O

analysing of harmonics:-block by 2. & 3. or 5.har-cross block

Motor start

DC off set

Power Automation 30



Tripping Characteristic Reasons for this shape of characteristic

2.0 8.0 9.0

3.0

InOIRest

InO

IDiff

7.0

2.5

Slope 1

Slope 2

IDiff>

01.0 4.0 5.03.0 6.00

1.0

0.5

2.0

1.5

x

Trip

Block

Total

CT-

error

Tap-

changer

Magnet.

current

Example: Transformer with Tap changer

Power Automation 31



Tripping Characteristic (1 of 2)

flexible adaptation to various transformers, e.g. with tap changer or different Cts

high stability against external faults with Ct saturation

IDiff>>: fast tripping for solid short-circuits within one period

20

4 8 106 120

2

1

4

3

6

7

1614

5

Tripping Characteristic 7UT6

Trip Block

1231 IDiff>>

1244A

BASE POINT 2

1241A

SLOPE 1

1243A

SLOPE 2

1221 IDiff>

Add-on

Stabilization

45

InO

IRest

InO

IDiff

1256A

I-ADD ON STAB

1242A

BASE POINT 1

*)

*) Slope for Add-on Stabilization:

7UT6 Slope 1 ; 7UT5 Slope 1

Power Automation 32



Tripping Characteristic (2 of 2) - Parameters

7UT613 / 63x

min. setting:

7UT6: 3 ; 7UT5: 5

7UT6 only

7UT6: settable

7UT5: 0 (fixed)

Power Automation 33



Tripping Characteristic - Pickup of differential function

For triggering of internal tasks, events and fault records the differential protection function needs a pickup information. This pickup becomes active, if the differential current or the restraint current is over an internal threshold(dotted line). Each external large current leads to a pickup.

Pickup doesnt always mean internal failure!

Power Automation 34



Tripping Characteristic (1 of 2) - Add on stabilization during external fault

Immediately after fault inception (A) the fault currents increase severely thus producing a high

restraint quantity. At the instant of Ct saturation (B) a differential quantity is produced and the restraint

quantity is reduced. In consequence, the operating point IDiff/IRest may move into the tripping area (C).

In contrast, the operating point moves immediately along the fault characteristic (D) when an internal

fault occurs.

When an external fault is detected, the differential stage for this phase is blocked by an

adjustable no. of periods. (for 7UT613/63x now also cross block is possible)

During an external fault which

produces a high

through-flowing current,

causing Ct saturation,

a considerable differential-

current can be simulated,

especially when the degree of

saturation is different at the

two sides.

If the quantities IDiff/IRest result

in an operating point which

lays in the trip area of the

operating characteristic, a

trip signal would be the

consequence, if there were no

special measures0A

2 4 8 106 120

2

1

4

3

Tripping Characteristic 7UT6

Trip

6

7

16

IDiff>>

14

5

IDiff>

Add-on

Stabilization

45

InO

IRest

InO

IDiff

Block

Saturation inceptionB

D

C

Power Automation 35



Tripping Characteristic (2 of 2)- Demonstration of add-on stabilization

add-on

stabilisati

on

45

Block

Trip

Power Automation 36



Tripping Characteristic - Motor Start

Typical for motor start is the starting current and the superimposed dc component witha large time constant. The two Ct-sets may transform this dc component differently.The result is a differential current and the risk of an over-function is given.

Detection of motor starting:Increases the pick-up values for a settable time

Criterion:Supervision of restraint current

IRest > I-Restr. Startup(until 2 I/InO)

than the Start-Factor (max. 2)is active for the time:

T Start Max(Duration of dynamical increasing of pickup)

20

4 8 106 120

2

1

4

3

Tripping Characteristic 7UT6 for Motor start

Trip

Block

6

7

16

1231 Idiff>>

14

5

Steady-state

characteristic

1221 Idiff>

45

InO

IRest

InO

IDiff

Start-up characteristic

Increase

of pickup

Power Automation 37



Tripping Characteristic DC offset: Increasing of the Characteristic

0.12

0.24

0.18

0.36

Minimum

setting

Add-on

stabilization

Setting Add-on stabilization:

5

7UT613/63x only

Steady state

characteristic

increased

characteristic

(factor 2)

Power Automation 38



Inrush, cross block, over excitation [V/Hz] (1 of 2)

recognise inrush condition by evaluating the ratio 2nd harmonic I2har to basic wave IDiff.

Time limit for cross-block. Reliable reaction to the inrush condition with cross-block.Trip of a short circuit after the set time delay.

recognise over excitation [V/Hz] by evaluating the ratio 3rd or 5th harmonic to basic wave

Cross-block = Yes (blocking of all phases)

O R1

L1-block

L2-block

L3-block

IDiff > trip blocking

for an adjustable time

filter window1 cycle

t1P 2P 3P

iRUSH = iDiff Inrush current

in one phase

Setting

value

t

15 %

no block

blockDiff

2har

I

I

00

L1-block

L2-block

L3-block

Cross-block = No (phase separate blocking)

IDiff, L1 > trip blocking



Power Automation 39



Inrush, cross block, over excitation [V/Hz] (2 of 2)Demo: Inrush followed by an internal Fault L1-E

3 cycles

Inrush

Internal

fault

IDiff>>

Add-on

stabilizati

onIDiff>

Power Automation 40



Low impedance Restricted Earth Fault (REF) (1 of 2)

The REF measures the Neutral current of the object ( ISP = 3I0 ) and, depending on the

angle () between 3I0 and the also measured sum of the phase currents

( 3I0 = IL1 + IL2 + IL3 ), decides for internal or external fault.

The sensitivity of the REF is almost independent from the load of the object.

(The sensitivity of the Differential Function especially for high ohm faults will be

reduced by the load due to the slope of its Tripping Characteristic ).

The REF can be stetted to 0.1 I/INO (min. 0.05) and is therefore more sensitive as the

Differential Protection (even without load).

Power Automation 41



Low impedance Restricted Earth Fault (REF) (2 of 2)

calculation of the basic wave and the complex vectors of I0' and I0"

evaluation of the modulus and angle between I0' and I0"

sensitive fault detection starting with 5% transformer nominal current

90 0

basic Trip-Area180 > 90

extended Trip-Area

-0.1-0.2-0.3 +0.3+0.1 +0.2

1

2

3

4

0.0

REF

REF

I

I

'

0

''

0 3I3I

Tripping

Blocking

Char. for

= 180

Tripping Characteristic REF

2) for extended Trip-Area (90 180):

IREF> = Setting value (Trip Threshold)

IRest = Restraint current

IREF = 3I0

1) for basic Trip-Area (0 90):

IREF = 3I0 and must be IREF>

Characteristic_1): IREF / IREF> = 1

(no restraining current IRest effective)

Characteristic_2): IREF = IREF> + kIRest

where IRest = (3I0-3I0-3I0+3I0)

IRest includes the direction

Power Automation 42



CT Requirements (1 of 3)

Request:

where:kALF_N = rated Accuracy Limiting Factor kALF = actual Accuracy Limiting Factor

Rct = secondary winding resistance

Rb = rated resistive burden Rb = actual resistive burden

IP = max. primary symmetrical short circuit current TP = Primary (Net-) Time constant

100msT:forI

I5

RR

RRkk

100msT:forI

I4

RR

RRkk

P

NCtPrim

P

'

bct

bctALF_NALF

P

NCtPrim

P

'

bct

bctALF_NALF

0.1

0.1

38.1 MVA

110/11 kV

uk = 10%

200/1A

5P20,15VA

Rct = 1

50m , 4 mm2

80m , 2.5 mm2

110 kV

Example: (TP 100ms)

2000/1A

10P10, 10VA

Rct = 2

11 kV

7UT6

Wind.1

Wind.2

Explanation:

5P20: kALF_N = 20

Power Automation 43




200A110kV3

38100kVA

U3

SInO

N1

N1

2200A100%10%

200A1.1100%

u

InOcI

k

1P_1

151A

15VA

I

SR

22

NCtS

bb

1.220.12.5mm

m

mm0.0175160m

Rq

l2R

2

2

Relay

'

b

1441.221

15120kALF

Side 2 (LV):

2000A11kV3

38100kVA

U3

SInO

N2

N2

22000A100%10%

2000A1.1100%

u

InOcI

k

2P_2

101A

10VA

I

SR

22

NCtS

bb

47.20.542

10210kALF

Side 1 (HV):

0.540.14mm

m

mm0.0175100m

Rq

l2R

2

2

Relay

'

b

Maximum through flowing current: Maximum through flowing current:

OK!44200A

2200A4

I

I4144k

NCTprim

PALF OK!44

2000A

22000A4

I

I447.2k

NCTprim

PALF

where: c = factor for max. possible over voltage where: c = factor for max. possible over voltage

Nominal transformer current: Nominal transformer current:

Power Automation 44




5P20, 200/1A, 15VA, Rct = 1, Rb = 1.22, 11I/INCT ; TP = 100ms

10P10, 2000/1A, 10VA, Rct = 2, Rb = 0.54, 11I/INCT ; TP = 100ms

Power Automation 45




WEB-Technology

The homepage of the relayis:http://141.141.255.160IP-address is set with DIGSI 4on front- or rear service port

WEB server in the relays firmware

Server sends its HTML-pages and JAVA-code to the WEB Monitorafter a DIAL-UP connection

2. HTML page view in a WEB Monitorwith the IP-address of the relayhttp://141.141.255.160

Help system in INTRANET / INTERNEThttp://www.siprotec.com

1. Serial connection

Direct or via modem with a

standard DIAL-UP Network

Access to the relay with a WEB Monitor

Power Automation 46




Transformer YNd11d11, 110/11/11kV, 38.1MVA, IL2S2 wrong polarity

Power Automation 47




Transformer YNd11d11, 110/11/11kV, 38.1MVA, IL2S2 wrong polarity

Power Automation 48




Power Automation 49



Protection relay with flexible adaptation to the transformer/generator/motoror short line. Programming of the device data in the relay.

Reduced amount of wiring by direct connection to the main Cts.No matching transformers and therefore no wiring errors.

Zero sequence current can be measured (in the 7UT6).Sensitivity for single-pole faults in the transformer increased by 33% .

Flexible adaptation of the tripping characteristic to various main Cts, tapped transformers.

Exact discrimination between the short circuit condition and the inrushcondition by on-line analysis of the harmonics. Fast tripping for high-current faults. Ct saturation detector for external faults.

Thermal monitoring of one transformer winding (including RTD meas.)

Back-up DMTL/IDMTL with reverse blocking for one winding.

Sensitive short circuit protection for faults winding against earth.

External Trip functions

Various commissioning aids.

Common DIGSI 4 software

Benefits for the Customer

Power Automation 50



Comparison of functions/settingsbetween 7UT51- and 7UT6 relays

7U

T5

1

7U

T6

12

7U

T6

13

7U

T6

33

7U

T6

35

Tripping Characteristic: Base point for slope 1 settable --- X X X X

Tripping Characteristic: Increasing of characteristic at start --- X X X X

Tripping Characteristic: minimum setting for add-on stabilization I/InO 5 3 3 3 3

Tripping Characteristic: cross block for add-on stabilization --- --- X X X

Tripping Characteristic: slope of add-on stabilization / slope 1 1 1 1 1

Tripping Characteristic: Increasing of characteristic due to DC offset in IDiff --- --- X X X

Transformer inrush: Default setting for cross block 2. harmonic [cycles] 0 3 3 3 3

Transformer inrush: Default setting for 5. harmonic [%] 80 30 30 30 30

Negative sequence current protection --- X X X X

Over excitation protection [V/Hz] --- --- X X ---

Overload protection IEC 60354 (hot spot) --- X X X X

Single phase busbar differential --- X X X X

High impedance Restricted Earth Fault --- X X X X

Voltage measurements --- --- X X ---

Temperature monitoring (via Thermo-box / RS 485) --- X X X X

All functions can be enabled at the same time --- X X X X

WEB Toll (commissioning aid) --- X X X X

Documents

7UT61X Transformer Protection