Figure. 5.4.18. - 89. Simpli ed function block diagram of the UPW function.
Measured input values
Three phase active power value is used for the function block. For pre-fault data registering -20ms
averaged value is used. If the protection relay has more than one CT module parameter Measured side
determines which current measurement is used for the power measurement.
Table. 5.4.18. - 149. Measurement magnitudes used by the UPW function.
Signal
Description
Time base
3PH Active power (P)
Total 3 phase active power
5 ms
Pick-up characteristics
Pick-up of the UPW function is controlled by
Pset<
setting parameter, which de nes the maximum
allowed measured three phase active power before action from the function. The function constantly
calculates the ratio in between of the Pset< and measured magnitude (Pm). Reset ratio of 97 % is
inbuilt in the function and is always related to the Pset< value.
Figure. 5.4.18. - 90. Activation and deactivation characteristics of the Under Power functions Low Power Blocking.
AQ-F255
Instruction manual
Version: 2.00
157
© Arcteq Relays Ltd