9.3 Protection stages
9 Technical data
Technical description
172
VAMP 24h support phone +358 (0)20 753 3264
VM55.EN005
9.3.2.
Frequency protection
VS_f_Over f_Over1
Overfrequency and underfrequency stages f>< and f>><<
(81H/81L)
Frequency measuring area
16.0 – 75.0 Hz
Current and voltage meas. Range
45.0 – 65.0 Hz
Frequency stage setting range
40.0 – 70.0 Hz
Low voltage blocking
10 – 100 %Un *)
Definite time function:
-operating time
0.10**
)
– 300.0 s (step 0.02 s)
Starting time
<100 ms
Reset time
<120 ms
Reset ratio (f> and f>>)
0.998
Reset ratio (f< and f<<)
1.002
Reset ratio (LV block)
Instant (no hysteresis)
Inaccuracy:
- starting
±20 mHz
- starting (LV block)
3% of the set value or ±0.5 V
- operating time
±1% or ±30 ms
*) 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! 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.
VS_f_Over f_Under1
Underfrequency stages f< and f<<
Frequency measuring area
16.0 – 75.0 Hz
Current and voltage meas. Range
45.0 – 65.0 Hz
Frequency stage setting range
40.0 – 64.0 Hz
Low voltage blocking
10 – 100 %U
N
*)
Definite time function:
-operating time
0.10
**)
– 300.0 s (step 0.02 s)
Undervoltage blocking
2 – 100 %
Starting time
<100 ms
Reset time
<120 ms
Reset ratio
1.002
Reset ratio (LV block)
Instant (no hysteresis)
Inaccuracy:
- starting
±20 mHz
- starting (LV block)
3% of the set value or ±0.5 V
- operating time
±1% or ±30 ms
*) Suitable frequency area for low voltage blocking is 45 – 65 Hz. Low voltage blocking is
checking the maximum of line to line voltages.
**) This is the instantaneous time i.e. the minimum total operational time including the fault
detection time and operation time of the trip contacts.
VS_dfdt dfdt
