Siemens SIPROTEC 4 7UT6 Series - Page 411

IfN Current at nominal frequency
Inf Current at n times the frequency (n = 3 oder 4)
[tdfrequenzeinf-trafo-7ut613, 1, en_GB]
Figure 4-4
Frequency influence in transformer differential protection
Idiff
Differential current = |Ι
1
+ Ι
2
|
INObj Nominal current of protected object
IXf Current at any frequency within specified range
Operating Times (Generators, Motors, Reactors)
7UT612
Pickup time / dropout time with single-side infeed
Pickup time at frequency 50 Hz 60 Hz
at 1.5 · setting Ι
Diff
>
at 1.5 · setting Ι
Diff
>>
at 5 · setting Ι
Diff
>>
38 ms
25 ms
19 ms
35 ms
22 ms
17 ms
Dropout time, approx. 35 ms 30 ms
Drop-off to pickup ratio approx. 0.7
7UT613/63x
Pickup time / dropout time with single-side infeed
Pickup time at frequency 50 Hz 60 Hz 16.7 Hz
Ι
Diff
> min
fast relays 30 ms 27 ms 78 ms
high-speed relays 25 ms 22 ms 73 ms
Ι
Diff
>> min
fast 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
Technical Data
4.2 Differential Protection
SIPROTEC 4, 7UT6x, Manual 411
C53000-G1176-C230-5, Edition 09.2016