FANOX SIL-G, User Manual

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7 FREQUENCY PROTECTION FUNCTIONS
To be able to trip with any of the protection functions, the setting Function Enable must be set to a value
different to No. We have 2 different options: Alarm or Trip.
In both cases the function will trip, but only if the Function Enable is set to Trip the protection function
will participate in the GENERAL TRIP.
7.1 Function 81U/O. Under/Overfrecuency
This protection function can be set by using the following parameters:
Function Description Minimum Maximum Step Unit Default
81_1
81_2
81_3
81_4 Under/Overfrequency
Function Enable - - No/Alarm/Trip - No
Type - -
(1)
- Overfrequency
Activation level 45.000 65.000 0.001 Hz 55.000
Time Delay 0.020 300.000 0.001 s 0.200
Reset time 0.020 300.000 0.001 s 0.200
(1) Overfrequency or Underfrequency
The four functions can be independently configured as overfrequency or underfrequency units.
If the unit is set as overfrequency, activation of the function occurs at 100% frequency level set and its
reset when the measured frequency is 50mHz lower than set start level.
If the unit is set as underfrequency, activation of the function occurs at 100% frequency level set and its
reset when the measured frequency is 50mHz higher than set start level.
The reset time is configurable.
The frequency measurement is done from the voltage of phase B. It has a hysteresis for its activation:
it takes a minimum of 20 volts P-N (35 volts P-P) for 81 functions to be operational. If the measured
phase voltage is less than 15 volts P-N (26 volts P-P), it activates a state bit (
Busbar Frequency Block )
indicating function blocked. When the frequency measurement is valid again, function begins in the start
state with all bits reset.
The accuracy of the Time Delay is equal to the set time delay ±35ms or ±0.5% (whichever is greater).