©2015 Siemens Protection Devices Limited
Chapter 7 Page 19 of 64
W1 Internal Phase-Phase Fault
x 1.02
B
B
B
O
O
O
O
O
O
ICT Multiplier
ICT Connection
87HS
87T
1
1
1.00
1.00
B-C Fault
0.589
0.589
1.178
x 1.06
Y
y
0
(
0
o
)
Yd11 (30
o
)
A
B
C
Y
d
1
1
(
3
0
o
)
1.02
1.02
Figure 2-8: Relay Currents - Star Winding Internal Phase Fault
Notes
B - C fault causes current to flow in the A, B and C elements
The Yd ICT connection causes a 1:2:1 current distribution and introduces a 1/ 3 multiplying factor.
Relay may indicate three phase fault
Summary of Contents for 7SR242 Duobias
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