7UT61X Transformer Protection

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The year of Profitable Growth

Global network of innovation

Module 10B:

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Power Automation 2

Power Automation

Progress. It‘s that simple.

FACTS SITRAM+ Siemens Transformer Monitoring System for all voltage levels Generator transformer System interconnecting transformer Shunt reactor Oil-immersed distribution transformer GEAFOL cast-resin transformer Traction transformer HVDC System transformer Converter transformer Furnace transformer Voltage regulator TLM50+ Siemens Transformer Life Management Program

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

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Power Automation 4

630-kVA Oil-Immersed Distribution Transformers, TUMETIC, TUNORMA

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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$ =

1’600.000US$

>1000 MVA

5,-US$ pro kVA =>

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Power Automation 6

On-site services and repair SITRAD Condition assessment program SITRAM+ transformer monitoring system Traditional heat and

vacuum treatment

SIDRY, SMART DRY, SIREC advanced life extension programs

TLM50+ – Siemens Transformer Life Management Program

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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

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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)

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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

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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

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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

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Connection Example

direct connection to the main Ct’s

no matching transformers / no matching connections numerical vector group adaptation without zero sequence current correction depending of the type of earthing of the winding.

increased sensitivity by 33% by measuring of the zero sequence current (7UT6) for single-pole faults.

1A/5A main Ct’s adaptation in the relay

permissible ratio Ct nominal current to transformer nominal current up to 1 : 4 IL2M1 IL1M3 IL2M2 IL3M2 IL2M3 IL3M1 IL3M3 IL1M2 IX1 IX3 I_L1M1 7UT613 M1 M3 M2 side 2 side 1 side 3 Surface mounting housing Flush/ cubicle-mounting housing L1 L2 L3 L1 L2 L3 L1 L2 L3

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Power Automation 14

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

M1 400/1A M2 400/1A M3 400/1A M4 8000/1A M5 3500/1A Side 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

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

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Power Automation 16

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

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

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Power Automation 18

Application: Autotransformer with ∆ Winding (1 of 2)

7UT613 M1 M2 M3 IL1M2 IL2M2 IL3M2 IL1M1 IL2M1 IL3M1 IL1M3 IL2M3 IL3M3 Side 3 Side 1 Side 2

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

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Power Automation 20

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

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Application: Autotransformer (bank) with (1 of 2) 3 Ct’s 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!

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Power Automation 22

Application: Autotransformer (bank) with (2 of 2) 3 Ct’s at the neutral side

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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

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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

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Application: Single-phase bus bar (1 of 2)

- configuration with Summation Ct’s

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

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Power Automation 26

Application: Single-phase bus bar (2 of 2)

- configuration with Summation Ct’s

Not important in this case

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General Applications (1 of 2)

1 ½ C.B. application with two winding transformer

7UT613 7UT633

Three winding transformer 1 or 3 phases 7UT613 7UT633 Short lines (2 ends) 7UT612 Short lines (3 ends) 7UT613 7UT633

Two winding transformer 1 or 3 phases

7UT612 7UM62

1 ½ C.B. application on HV and LV side with two winding transformer

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Power Automation 28

General Applications (2 of 2) Unit Protection (Overall Differential) Y ∆ G 3~ 7UT635 Generator/Motor longitudinal or transversal differential protection

7UT612 7UM62

G/M 3~

High-impedance

Restricted Earth Fault Protection

IEEinput

of the unit

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Differential functions I_Diff> and I_Diff>>

I_Diff> restrained (biased) differential function, I_Diff> = f(I_Rest) - Ct-saturation detector (add on stabilization) for external faults.

I_Diff>> fast unrestrained high current differential function, it’s setting therefore should be higher then the maximum possible through flowing current! Example Transformer: I_Diff>> > (1/u_k)·InO

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

The I_Diff>> 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>> 2·IDiff>> IDiff> _I Rest IDiff IDiff iDiff & Trip_I Diff> ≥1 Trip_I Diff>> Instantaneous values fundamental wave: IDiff= rms(iDiff)50Hz

iRest= │i1│ + │i2│

rectified mean value:

IRest= iRest measured value pre-processing ( vector gr. ,Ct’s ) side 1 i1L i2L side 2 iDiff = i1+ i2 Tripping characteristic, saturation detection iRest IRest ms I / In O iDiff IDiff ms I / In O analysing of harmonics: -block by 2. & 3. or 5.har -cross block

Motor start DC off set

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Power Automation 30

Tripping Characteristic Reasons for this shape of characteristic

2.0 8.0 9.0 3.0 InO I_Rest InO I_Diff 7.0 2.5 Slope 1 Slope 2 IDiff> 0 1.0 3.0 4.0 5.0 6.0 0 1.0 0.5 2.0 1.5 x Trip Block Total CT-error Tap-changer Magnet. current

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Tripping Characteristic (1 of 2)

flexible adaptation to various transformers, e.g. with tap changer or different Ct’s high stability against external faults with Ct saturation

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

2 0 4 6 8 10 12 0 2 1 4 3 6 7 16 14 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 I_Rest InO I_Diff 1256A I-ADD ON STAB 1242A BASE POINT 1 *)

*) Slope for Add-on Stabilization:

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Power Automation 32

of 2) - Parameters 7UT613 / 63x min. setting: 7UT6: 3 ; 7UT5: 5 7UT6 only 7UT6: settable 7UT5: 0 (fixed)

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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.

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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 I_Diff/I_Rest 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 I_Diff/I_Rest 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 measures 0 A0 2 4 6 8 10 12 2 1 4 3

Tripping Characteristic 7UT6

Trip 6 7 16 IDiff>> 14 5 IDiff> Add-on Stabilization 45° InO I_Rest InO I_Diff Block Saturation inception B D C

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of 2)

- Demonstration of add-on stabilization

add-on stabilisati on 45 ° Block Trip

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Power Automation 36

Tripping Characteristic - Motor Start

Typical for motor start is the starting current and the superimposed dc component with a 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

I_Rest > 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) 2 0 4 6 8 10 12 0 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 I_Rest InO I_Diff Start-up characteristic Increase of pickup

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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)

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Power Automation 38

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

recognise inrush condition by evaluating the ratio 2nd harmonic I_2harto basic wave I_Diff. 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 R ≥1 L1-block

L2-block L3-block

IDiff> trip blocking

for an adjustable time filter window

1 cycle

t

1P 2P 3P

iRUSH

= iDiff Inrush current

in one phase Setting value t 15 % no block block Diff 2har I I 0 0 L1-block L2-block L3-block

Cross-block = No (phase separate blocking)

IDiff, L1> trip blocking

IDiff, L2> trip blocking

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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 on IDiff>

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Power Automation 40

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

The REF measures the Neutral current of the object ( I_SP= 3I₀’ ) and, depending on the angle (∆φ) between 3I₀’ _{and the also measured sum of the phase currents}

( 3I₀’’ = I_L1 + I_L2 + I_L3 ), 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/I_NO (min. 0.05) and is therefore more sensitive as the “Differential Protection” (even without load).

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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°≥ ∆φ ≥ 0° basic Trip-Area 180°≥ ∆φ > 90° extended Trip-Area -0.1 -0.2 -0.3 +0.1 +0.2 +0.3 1 2 3 4 0.0 REF REF I I ' 0 '' 0 3I 3I Tripping Blocking Char. for ∆φ= 180°

Tripping Characteristic REF

2) for extended Trip-Area (90° ≤ ∆φ ≤ 180°):

I_REF> = Setting value (Trip Threshold) I_Rest = Restraint current

I_REF= │3I₀’│

1) for basic Trip-Area (0° ≤ ∆φ ≤ 90°):

I_REF= │3I₀’│ and must be ≥ I_REF> Characteristic_1): I_REF/ I_REF> = 1

(no restraining current I_Rest effective)

Characteristic_2): I_REF= I_REF> + k·I_Rest

where I_Rest = (│3I₀’-3I₀’’│-│3I₀’+3I₀’’│) I_Rest includes the direction

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Power Automation 42

CT Requirements (1 of 3) Request:

where:

k_{ALF_N}= rated Accuracy Limiting Factor k_ALF= actual Accuracy Limiting Factor R_ct= secondary winding resistance

R_b= rated resistive burden R’_b= actual resistive burden

I_P = max. primary symmetrical short circuit current T_P = Primary (Net-) Time constant 100ms T : for I I 5 R R R R k k 100ms T : for I I 4 R R R R k k P NCtPrim P ' b ct b ct ALF_N ALF P NCtPrim P ' b ct b ct ALF_N ALF 0.1 Ω 0.1 Ω 38.1 MVA 110/11 kV u_k= 10% 200/1A 5P20,15VA R_ct= 1Ω 50m , 4 mm2 80m , 2.5 mm2 110 kV Example: (T_P ≤ 100ms) 2000/1A 10P10, 10VA R_ct= 2Ω 11 kV 7UT6 Wind.1 Wind.2 Explanation: 5P20:  k_{ALF_N} = 20

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CT Requirements (2 of 3) 200A 110kV 3 38100kVA U 3 S InO N1 N 1 2200A 100% 10% 200A 1.1 100% u InO c I k 1 P _1 15Ω 1A 15VA I S R ₂ ₂ NCt S b b 1.22Ω 0.1Ω 2.5mm m Ωmm 0.0175 160m R q ρ l 2 R ₂ 2 Relay ' b 144 1.22Ω 1Ω 15Ω 1Ω 20 kALF Side 2 (LV): 2000A 11kV 3 38100kVA U 3 S InO N2 N 2 22000A 100% 10% 2000A 1.1 100% u InO c I k 2 P _2 10Ω 1A 10VA I S R ₂ ₂ NCt S b b 47.2 0.54Ω 2Ω 10Ω 2Ω 10 kALF Side 1 (HV): 0.54Ω 0.1Ω 4mm m Ωmm 0.0175 100m R q ρ l 2 R ₂ 2 Relay ' b

Maximum through flowing current: Maximum through flowing current:

OK! 44 200A 2200A 4 I I 4 144 k NCT prim P ALF 44 OK! 2000A 22000A 4 I I 4 47.2 k NCT prim P ALF

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

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Power Automation 44

CT Requirements (3 of 3)

5P20, 200/1A, 15VA, Rct = 1Ω, R’b = 1.22Ω, 11·I/INCT; TP= 100ms

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Commissioning and operating aids (1 of 4)

WEB-Technology

The homepage of the relay

is:http://141.141.255.160 IP-address is set with DIGSI 4 on front- or rear service port

WEB server in the relays firmware

Server sends it’s HTML-pages and JAVA-code to the WEB Monitor after a DIAL-UP connection

2. HTML page view in a WEB Monitor

with the IP-address of the relay http://141.141.255.160

Help system in

INTRANET / INTERNET http://www.siprotec.com

1. Serial connection

Direct or via modem with a standard DIAL-UP Network

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Power Automation 46

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Power Automation 48

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Progress. It‘s that simple. Protection relay with flexible adaptation to the transformer/generator/motor

or short line. Programming of the device data in the relay.

Reduced amount of wiring by direct connection to the main Ct’s. 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 Ct’s, tapped transformers.

Exact discrimination between the short circuit condition and the inrush condition 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

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Power Automation 50

Comparison of functions/settings between 7UT51- and 7UT6 relays

7 UT 5 1 7 UT 6 1 2 7 UT 6 1 3 7 UT 6 3 3 7 UT 6 3 5

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 ½ 1 1 1 1

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

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

Transformer inrush: Default settingfor 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