Siemens 7SR21 Manual page 58

Apply a trip condition by injection of current to cause operation of a suitable protection element. Allow current to
continue after the trip at a level of 110% of the 50BF Setting current level on any phase. Measure the time for
operation of operation of 50BF-1 Delay and 50BF-2 Delay. Repeat the sequence with current at 90% of the 50BF
Setting current level after the element trip and check for no CB Fail operation.
50BF Setting (xIn)
50BF-I4 Setting
(xIn)
3.1.1.1 Element Blocking
The CB Fail function can be blocked by Binary Input Inhibit. This functionality should be checked.
©2010 Siemens Protection Devices Limited
Test Current
(110%)
(90%)
50BF CB Faulty Operation No Delay □
Test Current
(110%)
(90%)
50BF CB Faulty Operation No Delay □
Element
50BF
7SR21 & 7SR22 Argus Commissioning and Maintenance
50BF-1 Delay
No Operation □
50BF-1 Delay
No Operation □
50BF-2 Delay
No Operation □
Operation No Delay □
50BF-2 Delay
No Operation □
Operation No Delay □
BI Inhibits
Chapter 6 Page 58 of 69