Siemens 7SR21 Manual page 35

Calculated Timing values in seconds for TM =1.0
Curve
IEC-NI
IEC-VI
IEC-EI
IEC-LTI
ANSI-MI
ANSI-VI
ANSI-EI
Note that the operate time may be subject to the Minimum op time setting for the element and/or may have a
Follower DTL applied.
If VTS action is set to BLOCK, this option should be tested. Apply balanced voltage and current. Reduce a-phase
voltage to cause a VTS condition. Increase a-phase current and check that the element does not operate.
If VTS action is set to Non-Directional, this option should be tested. Apply balanced voltage and current. Reduce
a-phase voltage to cause a VTS condition. Increase a-phase current and check that the element operates at its
normal setting. Reverse the voltage phase direction whilst checking that the element does not reset.
2.8.3.1 Element Blocking
The Sensitive Earth Fault elements can be blocked by Binary Input Inhibit and VT Supervision. The Characteristic
can be made non-directional by VT Supervision. This functionality should be checked.
Element
51SEF-1
51SEF-2
51SEF-3
51SEF-4
50SEF-1
50SEF-2
50SEF-3
50SEF-4
©2010 Siemens Protection Devices Limited
7SR21 & 7SR22 Argus Commissioning and Maintenance
2 xIs
10.03
13.50
26.67
120.00
3.80
7.03
9.52
BI Inhibits
5 xIs
4.28
3.38
3.33
30.00
1.69
1.31
1.30
VTS action
Chapter 6 Page 35 of 69