Frequency Protection - Allen-Bradley Rockwell Automation 857 User Manual

10-14
Technical Data
857-UM001A-EN-P – July 2009
Table 10.32 – Zero sequence voltage stages U
Zero sequence voltage setting range
Definite time function:
- Operating time
Start time
Reset time
Reset ratio
Inaccuracy:
- Starting
- Starting UoCalc (3LN mode)
- Operate time

Frequency protection

Table 10.33 – Overfrequency and underfrequency protection stages f>< and f>><<
Frequency measuring area
Current and voltage meas. range
Frequency stage setting range
Low voltage blocking
Definite time function:
-operating time
Starting time
Reset time
Reset ratio (f> and f>>)
Reset ratio (f< and f<<)
Reset ratio (LV block)
Inaccuracy:
- starting
- starting (LV block)
- operating time
This is the instantaneous time i.e. the minimum total operational time including the fault
detection time and operation time of the trip contacts.
NOTE: Frequency measurement functions when secondary voltage
is over 5 V. f> low voltage block only freezes the present situation. If
start has appeared block freezes the start signal but there won't be a
trip. This means that trip cannot be blocked.
f< if device restarts for some reason there will be no trip even if the
frequency is below the set limit during the start up (Start and trip is
blocked). To cancel this block, frequency has to visit above the set
limit.
> and U >> (59N)
0 0
1 – 60 %U
0n
0.3 – 300.0 s (step 0.1 s)
Typically 200 ms
<450 ms
0.97
±2% of the set value or ±0.3% of the rated
value
±1 V
±1% or ±150 ms
16.0 - 75.0 Hz
45.0 – 65.0 Hz
40.0 – 70.0 Hz
10 – 100 %Un
0.10 – 300.0 s (step 0.02 s)
<100 ms
<100 ms
0.998
1.002
0.5 V or 1.03 (3%)
±20 mHz
3% of the set value
±1% or ±30 ms