differential protection 7ut6

Power Transmission and Distribution

Differential Protection 7UT6Applications / Engineering

General Applications (1 of 2)Two winding transformer 1 or 3 phases Three winding transformer 1 or 3 phases 1 C.B. application with two winding transformer

7UT613 7UT633 7UT612 7UM62 7UT613 7UT633

Short lines (2 ends)

Short lines (3 ends)

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

7UT635 7UT613 7UT633

7UT612

PTD PA 7UT6 Applicat./Eng. 06/04 No. 2

General Applications (2 of 2)Generator/Motor longitudinal or transversal differential protectionG/ M 3~ 7UT612 7UM62

High-impedance Restricted Earth Fault Protection

7UT6x x

Unit Protection (Overall Differential)

IEE input of the unit

YG 3 ~

7UT63 5


Application: 3-winding transformer YNd5d11 (1 of 4)IL1M /I1 1 M1 M2 400/1A M1 400/1A IL2M /I2 1 IL3M /I3 1 IL1M /I4 2 M2 IL2M /I5 2 IL3M /I6 2 IL1M /I7 3 M3 Side 1 200/1A M4 Side 3 Side 2 M5 M4 8000/1A M5 3500/1A IL2M /I8 3 IL3M /I9 3 IL1M /I1 4 IL2M /I1 41 0

M3 400/1A

IL3M /I1 42

IL1M /Ix 5 IL2M /Ix 52 1

IL3M /Ix 53

Ix4

7UT635PTD PA 7UT6 Applicat./Eng. 06/04 No. 4

Application: 3-winding transformer YNd5d11 (2 of 4) -Device Configuration and Power System Data 1 7UT635


Application: 3-winding transformer YNd5d11 (3 of 4) -continue Power System Data 17UT635


Application: 3-winding transformer YNd5d11 (4 of 4) -continue Power System Data 17UT635


Application: Autotransformer with Winding (1 of 2)M1 M2Side 1 Side 2 Side 3

M3

IL1M 2 IL2M 2 IL3M 2



7UT61 3PTD PA 7UT6 Applicat./Eng. 06/04 No. 8

7UT61 3

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


Application: Autotransformer (bank) with (1 of 2) 3MCts at the star point side available M1 M 2 3

Only compensation winding, no external connection!

Increased sensitivity for phase to phaseand phase to ground faults towards the star point!

7UT61 3


Application: Autotransformer (bank) with (2 of 2) 3 Cts at the neutral side7UT61 3


Application: Single-phase bus bar (1/2) - Phase selective configuration (1 7UT6 for 1 phase) 7UT612:7 currentinputs 7UT613/63 3: 9 currentinputs 7UT635: 12 currentinputs

7UT61 2


Application: Single-phase bus bar (2/2) - Phase selective configuration (1 7UT6 for 1 phase) 7UT6122 more Relays for Phase 2 and 3 are necessary


Application: Single-phase bus bar (1 of 2) - configuration with Summation Cts7UT612: 7 currentinputs 0.1A 7UT613/63 3: 6 currentinputs 0.1A 7UT635: 12 current inputs 0.1A *) Summation CT4AM5120-3DA00-0AN2: 1/0.1A 4AM5120-4DA00-0AN2: 5/0.1A 7UT61 2


7UT61 2

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

Not important in this case


Terminology of a topology (Example 1)Device ConfigurationM1 S 1 0105 0112 0113 0120 0124 0127 Protected Object Differential Protection REF Protection DMT/IDMT Phase DMT/IDMT Earth DMT 1Phase 3 phase Transformer Enabled Enabled Definite Time only Definite Time only Enabled

Main protect. object S 2

X1

M3 M2 M4 Further protected object

Sides: S1 High voltage side (HV) S2 Low voltage side (LV) S3 Low voltage side (LV) Measuring locations 3-phase , assigned M1 assigned to the main protected object (side 1) M2 assigned to the main protected object (side 2) M3 assigned to the main protected object (side 3) Measuring locations 3-phase , non-assigned M4 not assigned to the main protected object Auxiliary measuring locations 1-phase

YS 3

Power System Data 1X4

7UT63 5

X2

CT-Numbers 0211 No. of connected Meas. Loc. 4 0212 No. of assigned Meas. Loc. 3 0213 No. of sides 3 CT-Assign 0222 Assignment at 3 assig. Meas.Loc./3 sides S1:M1, S2:M2, S3:M3 0251 Auxiliary CT IX1 is used as Side 1 earth 0252 Auxiliary CT IX2 is used as Measurement location 4 earth 0253 Auxiliary CT IX3 is used as not connected 0254 Auxiliary CT IX4 is used as connected/not assigned 0255 Type of auxiliary CT IX3 1A/5A current input 0256 Type of auxiliary CT IX4 sensitive current input Funct. 0413 REF assigned to not assigned measuring loc. 4 0420 DMT/IDMT Phase assigned to Measuring Location 4 0424 DMT/IDMT Earth assigned to Auxiliary CT IX1 0427 DMT Phase assigned to Auxiliary CT IX4


Terminology of a topology (Example 2)Device ConfigurationM1 S 1 Main protect. object S 2 M2 Starpointbilder X2 0105 Protected Object 0112 Differential Protection 0113 REF Protection X1 X3 0120 DMT/IDMT Phase 0127 DMT 1Phase 3 phase Transformer Enabled Enabled Definite Time only Enabled

Sides: S1 High voltage side (HV) S2 Low voltage side (LV) Measuring locations 3-phase , assigned M1 assigned to the main protected object (side 1) M2 assigned to the main protected object (side 2) Auxiliary measuring locations 1-phase X1 assigned to the main protected object (side 1) X2 assigned to the main protected object (side 2) X3 not assigned to the main protected

Y

Power System Data 1 7UT61 3CT-Numbers 0211 No. of connected Meas. Loc. 2 0212 No. of assigned Meas. Loc. 2 0213 No. of sides 2 CT-Assign 0222 Assignment at 2 assig. Meas.Loc./2 sides S1:M1, S2:M2 0251 Auxiliary CT IX1 is used as Side 1 earth 0252 Auxiliary CT IX2 is used as Side 2 earth 0253 Auxiliary CT IX3 is used as connected/not assigned 0255 Type of auxiliary CT IX3 sensitive current input Transf. . 0313 Starpoint of Side 1 is Solid Earthed 0314 Transf. Winding Connection Side 1 Y (Wye) . 0323 Starpoint of Side 2 is Solid Earthed (!!) 0324 Transf. Winding Connection Side 2 D (Delta) 0325 Vector Group Numeral of Side 2 11 Funct. 0413 REF assigned to Side 2 0420 DMT/IDMT Phase assigned to Side 1 0427 DMT Phase assigned to Auxiliary CT IX3

Setting Group ADifferential Protection-Settings Group A 1211A Diff-Prot. with PTD PA Earth Applicat./Eng. 06/04 No. 17 meas. 7UT6 Curr. S1 Yes (Io-

Application: Transformer Data Base

RS485 interface

7XV5662(x)AD10

7XV5662(x)AD10

Two RTD boxes can be connected to the service interface (RS485) Monitoring of up to 12 measuring points (6 per RTD box) - each having two thresholds (Alarm stages) Display of the temperature as measured values - directly at the RTD box (can be used as stand alone device as well) - in the protection relay Monitoring of threshold values One dedicated input can be used for the hot spot calculation (oil temperature) The type of sensor can be selected for each measuring point (Pt100, Ni100, Ni120)PTD PA 7UT6 Applicat./Eng. 06/04 No. 18

Application: Overload with hot-spot calculation (1of 3) Transformer with ONAN-cooling the General is an - Protection Object The hot-spot temperature ofONAN cooling important value of status. The hottest spot relevant for the life-time of the transformer is usually situated at the insulation of the upper inner turn. Generally the temperature of the coolant increases from the bottom up. The cooling method, however, affects the temperature gradient. The hot-spot temperature is composed of two parts: - the temperature at the hottest spot of the coolant (included via RTD-box), - the temperature rise of the winding turn caused by the transformer load Hot-spot calculation is done with different equations depending on the cooling method. For ON-cooling and OF-cooling:

top oil temp.

H V LV

h = O + H gr k Y

with: h= hot-spot temperature, O= top oil temperature, Hgr = hot-spot to top-oil gradient k = load factor I/IN (measured), Y = winding exponent The life-time of a cellulose insulation refers to a temperature of 98 C or 208.4 F in the direct environment of the insulation. Experience shows that an increase of 6 K results h half of hthe life-time. Ageing at in V= = 2( 98)/6 For a temperature which defers from the basic value of Ageing at 98C 98 C (208.4 F), the relative ageing rate V is given by: The mean value of the relative ageing rate L is given by the calculation of the mean value of a certain period of time, i.e. from T1 to T2:2 1 L= V dt T2 T1 T1

T


Application: Overload with hot-spot calculation (2of 3) Transformer with ONAN-cooling - Example 1.(page 1) Settings:

From TransformerManufacturer

In case of no Information Manual 7UT61:

2. Results:


Application: Overload with hot-spot calculation (3of 3) Transformer with ONAN-cooling - Example (page 2)(L)

h = o + H gr k Y 73 + 23 1.151.6 = 102C V = 2( h 98)/6 = 2 (10298)/6 1.6108C

k, V, L

102C98C

[C ]

h

73C 1.6o

h

hot-spot

temp. top oil temp. (by 1.1 5

o

Thermo-box) k (I/InO)

V (relative ageing rate) L (mean value of V)

tPTD PA 7UT6 Applicat./Eng. 06/04 No. 21

CT Requirements (1 of 3)Request: k ALF = k ALF_Nk ALF = k ALF_N R ct + R b I 4 P for : TP 100ms ' R ct + R b I NCtPrim R ct + R b I 5 P for : TP > 100ms ' R ct + R b I NCtPrim

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 Example: (TP 100ms)110 kV 7UT6 200/1A 5P20,15V A Rct = 1 38.1 MVA 110/11 kV uk = 10% 2000/1A 10P10, 10VA Rct = 2 Wind.2 0.1 80m , 2.5 mm2 Wind.1 0.1

Explanation: 5P20: kALF_N = 20

50m , 4 mm2

11 kV


CT Requirements (2 of 3)Side 1 (HV):Nominal transformer current:

Side 2 (LV):Nominal transformer current:

InO1 =

SN 38100kVA = 200A 3 U N1 3 110kV

InO 2 =

SN 38100kVA = 2000A 3 U N2 3 11kV

Maximum through flowing current:

Maximum through flowing current:

I P_1 =

c InO1 1.1 200A 100% = 100% = 2200A uk 10%

I P_2 =

c InO2 1.1 2000A 100% = 100% = 22000A uk 10%

where: c = factor for max. possible over voltage

where: c = factor for max. possible over voltage

Rb =

Sb I2 NCtS

=

15VA = 15 1A 2160m 0.0175 2.5mm mm 2 m + 0.1 = 1.22 2

Rb =

Sb I2 NCtS

=

10VA = 10 1A 2100m 0.0175 4mm mm 2 m + 0.1 0.54 2

R 'b =

2l + R Relay = q

R 'b =

2l + R Relay = q

k ALF = 20

1 + 15 = 144 1 + 1.22 IP I NCTprim =4 2200A = 44 OK! 200A

k ALF = 10

2 + 10 = 47.2 2 + 0.54

k ALF = 144 4

k ALF = 47.2 4

IP I NCTprim

=4

22000A = 44 OK! 2000A


CT Requirements (3 of 3)5P20, 200/1A, 15VA, Rct = 1, 100ms Rb = 1.22, 11I/INCT ; TP =

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


7UT6: CT Adaptation Factor of 3)

(1

Especially for 3- and more leg Differential Example: Protection with very different loads in the individual legs it can be necessary UN to install an additional Interposing CT . SN The Adaptation factor can be calculated according the formula: ICTprim I NCTprim 3 UN ICTsec FAdap = I Relay I NCTsec S N_max INRelay Where SN_max is always the maximum load of the Transformer. Condition for 7UT6: 0.25 < FAdap < 4(b ju p rs y me )

Maximum ratio of nominal primary CT current to nominal object current.Winding 1 347 kV 250 MVA (SN_mx ) a 1000 A 1A 1A 2.404 Ok! Winding 2 15.7 kV 200 MVA 9000 A 5A 5A 0.979 Ok! Winding 3 6.3 kV 10 MVA 1000 A 5A 5A 0.044 **)

Factor (calculated)

* *) FAdap_Wdg3 =

1000A 3 6.3kV 5A 0.044 5A 250000kVA

For Winding 3 the Adaption factor is to low ! Here an Interposing CT with a ratio of 6 or greater should be installed.



(2

Maximum ratio of nominal primary CT current to nominal object current.347 kV 7UT613 Side 1 1000/1A

250/200/10 MVA

Side 2 9000/5A Side 3 1000/5A 6/1 Interposing CT

15.7 kV

6.3 kV



(3

Maximum ratio of nominal primary CT current to nominal object current.CT Adaption factors without Interposing CT:

CT Adaption factors with Interposing CT (Ratio : 6):

Settings CT winding 3:


Setting the direction of the Star point CTTransformerwinding L1 L2 L3 Q7 Q8 7UT61 Q7 Q8 7UT61 Q7 Q8

0230 Earthing Electrode versus Q7 0230 Earthing Electrode versus Q7 0230 Earthing Electrode versus Q8 0230 Earthing Electrode versus Q8

Terminal

Terminal Terminal

7UT61 Q7 Q8

Terminal

7UT61


7UT6: Default setting for 5th harmonic restraint (1 of 2The fundamental component of the magnetising current appears as differential current. Apart from abnormally high operating voltages, a voltage rise at the winding can occur due to single pole faults in a power system with solid earthed system neutral! This situation with factor 1.4 is marked as point 2 (Figure 1). The highest content of 5th harmonics is approximately there where the fundamental harmonic riches the setting Idiff>. Without 5th harmonic restraint the Differential protection would trip! The magnetising current contains for example at point 3 (50Hz pickup threshold) approximately 50% of this harmonic. The setting for 5th harmonic restraint should consider the smallest I250 / I50 for the applicable voltage range. In this example with Umax = 140% the setting for I250 / I50 should be at least 30%. Higher voltages require a lower setting of the restraint threshold. The 50Hz component of the magnetising current due to over flux in this case (Figure 1) does not exceed 1.5 InTr . This threshold (1273A) can also be set on the protection relay. As the 5th harmonic restraint is not effective above (1273A), it will not block during internal short circuits with harmonics for example due to CT saturation.


7UT6: Default setting for 5th harmonic restraint (2 of 2)Figure 1 50Hz part of the magnetisation current and dominant Harmonics at Over flux for a 50Hz Transformer with UN = 78kV and SN = 60MVA

Setting Idiff>

st ne nop m c c no m a H o i r

(for solid earthed system neutral


differential protection 7ut6

Documents

phase transformer

case ptd pa 7ut6 applicat

necessary ptd pa 7ut6

phase x1

phase ys

phaseand phase

phase 7ut6122

ix4 7ut635ptd pa 7ut6