Generator Relay Model: LHFRT

 

If Fref <= 0 then assumption is made that Fref = 60.0

The units of the dftrp1, dftrp2, … dftrp10 are based on the value of Fref. The test for determining whether the relay will trip is as follows.

Value = (Monitored Frequency in pu – 1.0)*Fref

If (dftrp1 > 0) and (Value > dftrp1) then activate timer for dttrp1 else Reset the timer

If (dftrp1 < 0) and (Value < dftrp1) then activate timer for dttrp1 else Reset the timer

Each timer acts independently of other timers. If a time remains active for longer than the respective dttrpX value, then it will trip the generator.

As an example, if the nominal frequency of your system in 60 Hz and you have trip levels of frequency at 65.0, 60.5, 59.3, 57.0, 50.0 Hz, then the following Fref and dftrpX values would be equivalent.

Fref dftrp1 dftrp2 dftrp3 dftrp4 dftrp5
60.0 5.0 0.5 -0.7 -3.0 -10.0
1.0 0.08333 0.00833 -0.011667 -0.05 -0.166667

Parameters:

Fref Frequency ref., Hz
dftrp1 Delta frequency trip level, Hz
dftrp2 Delta frequency trip level, Hz
dftrp3 Delta frequency trip level, Hz
dftrp4 Delta frequency trip level, Hz
dftrp5 Delta frequency trip level, Hz
dftrp6 Delta frequency trip level, Hz
dftrp7 Delta frequency trip level, Hz
dftrp8 Delta frequency trip level, Hz
dftrp9 Delta frequency trip level, Hz
dftrp10 Delta frequency trip level, Hz
dttrp1 Frequency trip time, sec.
dttrp2 Frequency trip time, sec.
dttrp3 Frequency trip time, sec.
dttrp4 Frequency trip time, sec.
dttrp5 Frequency trip time, sec.
dttrp6 Frequency trip time, sec.
dttrp7 Frequency trip time, sec.
dttrp8 Frequency trip time, sec.
dttrp9 Frequency trip time, sec.
dttrp10 Frequency trip time, sec.
Alarm If greater than zero, no tripping action is enforced; a message is printed when a trip level is exceeded.

Model supported by PSLF