4.2 Differential Protection
439
7UT613/63x Manual
C53000-G1176-C160-2
Operating Times (Generators, Motors, Reactors)
Operating Range Frequency (Generators, Motors, Reactors)
Figure 4-5 Frequency influence (generator / motor protection and busbar protection)
I
diff
differential current = |I
1
+ I
2
|
I
NObj
Nominal current of protected object
I
Xf
Current at any frequency within specified range
Differential Current Monitor (Busbars, Short Lines)
Pickup time / dropout time with single-side infeed
Pickup time at frequency 50 Hz 60 Hz 16.7 Hz
I
Diff
> min
high-speed relays 30 ms 27 ms 78 ms
high-speed relays 25 ms 22 ms 73 ms
I
Diff
>> min
high-speed relays 11 ms 11 ms 20 ms
high-speed relays 6 ms 6 ms 15 ms
Dropout time, approx. 54 ms 46 ms 150 ms
Dropout ratio approx. 0.7
Frequency influence within the frequency tagging range see Figure 4-5
Note:
Higher tolerances must be expected if I
N
= 0.1 A (device connected via summation current
transformers). Also, the device tolerances do not include measuring errors originating from
summation CTs and magnetizing currents.
Steady-state differential current monitoring
I
Monit
/I
NObj
0.15 to 0.80 Steps 0.01
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