Primary Injection / On Load Tests; Differential Protection - Siemens 7SG14 Duobias-M-200 Technical Manual

1.4 Primary Injection / On Load Tests

1.4.1 Differential Protection

1.4.1.1 Line And Relay Magnitude Checks From Relay Instruments
I P
NSTRUMENT RIMARY
C
URRENTS
W1 Phase A
W1 Phase B
W1 Phase C
W2 Phase A
W2 Phase B
W2 Phase C
Table 14 - Primary Inject Magnitude Check
1.4.1.2 Operate and Restrain Magnitude Checks From Relay Instruments
I A
NSTRUMENT
Operate Phase
A
Operate Phase
B
Operate Phase
C
Restrain Phase
A
Restrain Phase
B
Restrain Phase
C
Table 15 - Operate Currents Check
1.4.1.3 Phase Checks
P D W
HASE IFFERENCE OF INDING
C
URRENTS
A Phase
B Phase
C Phase
Table 16 - Primary Injection Phase Difference Check
The Winding (W1,W2 etc) ICT Currents for each phase should be in anti-phase. For a two winding transformer
the W1 ICT A phase current should be in anti-phase (180 degrees apart) with the W2 ICT A phase current. All
phases should be checked to ensure wiring errors are not present.
1.4.2 Restricted Earth Fault
T
EST
W1 Neutral CT
Normal Polarity
W1 Neutral CT
Reversed
W2 Neutral CT
Normal Polarity
W2 Neutral
Neutral CT Reverse
Table 17 - REF Primary Injection Tests
©2010 Siemens Protection Devices Limited
S C
ECONDARY URRENTS
(kA) (A) [B ICT]
EFORE
S
CUAL ETTINGS
ICT A P
NTI HASE
C
HECK
OK
OK
OK
P C REF S
RIMARY URRENT
I (A) C
NJECTED
7SG14 Duobias-M-200 Commissioning
ICT R C
ELAY URRENTS
( I ) [A ICT]
X FTER
N
180° U S
NBALANCED ETTINGS
ECONDARY
( A)
URRENT M
(no spill current)
(significant spill current)
(no significant spill current)
(significant spill current)
C
HECK
OK
OK
OK
OK
Chapter 7 Page 19 of 20