Chapter 6) 7SR23 DAD Commissioning & Maintenance Guide
©2013 Siemens Protection Devices Limited
Chapter 6 Page 14 of 26
2.2
3 Phase Differential Protection (87/50)
Figure 2-2 3 Phase Differential Protection
Current Inputs:
I
A
I
B
I
C
Disable:
CT50
Map Pickup LED:
87/50-n - Self Reset
The external stabilising resistor values should be measured and compared to that specified in the settings data.
Both values should be recorded.
Element
Settings Data: R
STAB
Value
R
STAB
Measured
87/50-1
87/50-2
The relatively high value of stabilising resistance R
STAB
will often interfere with secondary current injection when
using a digital test set. It is normal practice in these cases to short circuit the resistor to allow testing, the shorting
link should be removed after testing.
The pick-up setting can be tested by gradually increasing current until element operates. The relay should be
disconnected from the current transformers for this test.
Apply 2x setting current if possible and record operating time
Is
(Amps)
DTL
(sec)
P.U. Current
Amps
Operate Time
2 x Is
NOTES
87/50-1
87/50-2
Summary of Contents for 7SR23 DAD
Page 1: ...Answers for energy 7SR23 DAD High Impedance Protection Relay Reyrolle Protection Devices ...
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