Applications Engineering-en.ppt

Power Transmission and Distribution
Differential Protection 7UT6
Applications / Engineering

PTD PA 7UT6 Applicat./Eng. 06/04 No. 2
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
7UT635

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
IEE input
of the unit
7UT6xx

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

-Device Configuration and Power System Data 1
7UT635

-continue Power System Data 1
7UT635

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

Application: Autotransformer with ∆ Winding (2 of 2)
- Power System Data 1
7UT613

Application: Autotransformer (bank) with (1 of 2)
3 Ct’s at the star point side available
M
1 M
2
M
3
7UT613
Only compensation winding,
no external connection!
Increased sensitivity for
phase to phase- and
phase to ground faults
towards the star point!

Application: Autotransformer (bank) with (2 of 2)
3 Ct’s at the neutral side
7UT613

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

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

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

Application: Single-phase bus bar (2 of 2)
- configuration with Summation Ct’s
Not important
in this case
7UT612

Terminology of a topology (Example 1)
Device Configuration
0105 Protected Object 3 phase Transformer
0112 Differential Protection Enabled
0113 REF Protection Enabled
0120 DMT/IDMT Phase Definite Time only
0124 DMT/IDMT Earth Definite Time only
0127 DMT 1Phase Enabled
Power System Data 1
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
M4
X2
X1
Y
∆
7UT635
∆
M1
M2
M3
Main
protect.
object
S1
S3
S2
Further
protected object
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)
Measuring locations 3-phase , non-assigned
M4 not assigned to the main protected object
Auxiliary measuring locations 1-phase
X1 assigned to the main protected object (side 1)
X2 not assigned to the main protected object
X4

Terminology of a topology (Example 2)
Device Configuration
0105 Protected Object 3 phase Transformer
0112 Differential Protection Enabled
0113 REF Protection Enabled
0120 DMT/IDMT Phase Definite Time only
0127 DMT 1Phase Enabled
Power System Data 1
CT-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
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 A
Differential Protection-Settings Group A
1211A Diff-Prot. with meas. Earth Curr. S1 Yes (Io- correction Side 1)
1212A Diff-Prot. with meas. Earth Curr. S2 No
X2
X1
Y
∆
7UT613
M1
M2
Main
protect.
object
S1
S2
Starpoint-
bilder
Sides:
S1 High voltage side (HV)
Measuring locations 3-phase , assigned
Auxiliary measuring locations 1-phase
X3

Application: Transformer Data Base
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)
RS485 interface
7XV5662-(x)AD10 7XV5662-(x)AD10

Application: Overload with hot-spot calculation (1of 3)
Transformer with ONAN-cooling - General
The hot-spot temperature of the Protection Object is an
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:
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 in half of the life-time.
For a temperature which defers from the basic value of
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:
98)/6
(Θ
h h
2
C
98
at
Ageing
Θ
at
Ageing
V 



 



2
1
T
T
1
2
dt
V
T
T
1
L
Y
gr
O
h k
H
Θ
Θ 


HV
LV
top oil
temp.
ONAN - cooling

Transformer with ONAN-cooling - Example (page 1)
In case of no Information Manual 7UT61:
1. Settings:
From Transformer-
Manufacturer
2. Results:

Transformer with ONAN-cooling - Example (page 2)
1.6
2
2
V 98)/6
(102
98)/6
(Θh


 

C
102
1.15
23
73
k
H
Θ
Θ 1.6
Y
gr
o
h 







h
o
t
[°C]
98°C
h hot-spot temp.
1.6
102°C
1.15
73°C
k (I/InO)
108°C
k,
V,
L
V (relative ageing rate)
L (mean value of V)
o top oil temp. (by Thermo-box)
(L)

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 R’b = actual resistive burden
IP = max. primary symmetrical short circuit current TP = 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
uk = 10%
200/1A
5P20,15VA
Rct = 1Ω
50m , 4 mm2
80m , 2.5 mm2
110 kV
Example: (TP ≤ 100ms)
2000/1A
10P10, 10VA
Rct = 2Ω
11 kV
7UT6
Wind.1
Wind.2
Explanation:
5P20:  kALF_N = 20

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
NCtS
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
NCtS
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
NCTprim
P
ALF 



 OK!
44
2000A
22000A
4
I
I
4
47.2
k
NCTprim
P
ALF 




where: c = factor for max. possible over voltage where: c = factor for max. possible over voltage
Nominal transformer current: Nominal transformer current:

5P20, 200/1A, 15VA, Rct = 1Ω, R’b = 1.22Ω, 11·I/INCT ; TP = 100ms
10P10, 2000/1A, 10VA, Rct = 2Ω, R’b = 0.54Ω, 11·I/INCT ; TP = 100ms

7UT6: CT Adaptation Factor (1 of 3)
Maximum ratio of nominal primary CT current to nominal object current.
Example: Winding 1 Winding 2 Winding 3
UN 347 kV 15.7 kV 6.3 kV
SN 250 MVA
(SN_max)
200 MVA 10 MVA
ICTprim 1000 A 9000 A 1000 A
ICTsec 1 A 5 A 5 A
IN Relay
(by jumpers)
1 A 5 A 5 A
Factor
(calculated)
2.404
Ok!
0.979
Ok!
0.044
**)
Relay
N_max
N
NCTsec
NCTprim
Adap I
S
U
3
I
I
F 



0.044
5A
250000kVA
6.3kV
3
5A
1000A
F
*)
* Adap_Wdg3 





Where SN_max is always the maximum load
of the Transformer.
Condition for 7UT6: 0.25 < FAdap < 4
For Winding 3 the Adaption factor is to low ! Here an Interposing CT with a ratio of
6 or greater should be installed.
Especially for 3- and more leg Differential
Protection with very different loads in
the individual legs it can be necessary
to install
an additional Interposing CT .
The Adaptation factor can be calculated
according the formula:

15.7 kV
7UT613
250/200/10 MVA
347 kV
6.3 kV
1000/1A
9000/5A
1000/5A
6/1
Interposing CT
Side 1
Side 2
Side 3

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 CT
Transformer-
winding
L1
L2
L3
7UT61
Q7 Q8 0230 Earthing Electrode versus Terminal Q7
7UT61
7UT61
7UT61

7UT6: Default setting for 5th harmonic restraint (1 of 2
The 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)
(for solid earthed
system neutral
Harmonic
components
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>

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