Ct Supervision (Ct50) - Siemens 7SR23 DAD Manual

3.2

CT Supervision (CT50)

Current Inputs:
Disable:
Map Pickup LED:
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
CT50
The relatively high value of stabilising resistance R
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.
As a DTL is generally applied 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)
CT50
©2013 Siemens Protection Devices Limited
Chapter 6) 7SR23 DAD Commissioning & Maintenance Guide
Figure 3-1 CT Supervision
I I I
A B C
CT50
CT50 - Self Reset
Value
STAB
STAB
DTL P.U. Current
(sec) Amps
R Measured
STAB
will often interfere with secondary current injection when
Operate Time
2 x Is
NOTES
Chapter 6 Page 19 of 26