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2.2.1
Definite Time Overcurrent
If DTL setting is small, gradually increase current until element operates.
If DTL is large apply 0.9x setting, check for no operation, apply 1.1x setting, check operation
Apply 2x setting current if possible and record operating time
Input
Is
(Amps)
Check correct indication, trip output, alarm contacts, waveform record.
2.2.2
Inverse Time Overcurrent (51N)
It will be advantageous to map the function being tested to temporarily drive the relevant Pickup output in the
Pickup Config sub-menu in the Output Config menu as this will allow the Pick-up led to operate for the function.
Gradually increase current until Pickup LED operates.
Apply 2x setting current and record operating time,
Apply 5x setting current and record operating time.
Compare to calculated values for operating times
P.U.
Input
Char.
D.O.
(NI EI VI
&
LTI, DTL)
TIMIN
G
TEST
S
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.
©2010 Siemens Protection Devices Limited
7SR242 Duobias Commissioning & Maintenance Guide
(50N)
DTL
P.U. Current
(sec)
Amps
Is
T.M.
Operate Current
(A)
P.U.
(Amps)
2 xIs
10.03
13.50
26.67
120.00
3.80
7.03
9.52
Operate Time
2 x Is
Operate Time
NOTES
D.O.
2 x Is
(Amps)
(sec)
5 xIs
4.28
3.38
3.33
30.00
1.69
1.31
1.30
Chapter 6 Page 22 of 57
NOTES
5 x Is
(sec)
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