Figure. 5.4.15. - 85. Simpli ed function block diagram of the FRQV function.
Measured input values
Frequency protection function compares measured frequency to pick-up setting given in Hz. Source of
measured frequency depends on the factory de ned tracking reference which can be checked from
frequency tab behind measurements-menu.
Table. 5.4.15. - 137. Measurement magnitudes used by the FRQV function (depends on factory de ned)
Signals
Description
Time base
VT1 U1,U2,U3
L-N voltages of rst voltage transformer
5 ms
VT2 U1,U2,U3
L-N voltages of second voltage transformer
5 ms
Pick-up characteristics and time delay
Pick-up of each stage of FRQV functions stage is controlled by fset>, fset>> etc.setting parameter,
which de nes the maximum or minimum allowed measured frequency before action from the function.
The function constantly calculates the ratio in between of the pick-up setting and measured frequency.
Reset ratio of 97 % is inbuilt in the function and is always related to the pick-up value.
Table. 5.4.15. - 138. Pick-up characteristics setting
Name
Description
Range
Step
Default
fset>
fset>>
fset>>>
fset>>>>
Pick-up setting
10.00…80.00Hz
0.01Hz
51Hz
AQ-F255
Instruction manual
Version: 2.00
147
© Arcteq Relays Ltd