Toshiba GR-200 Series Instruction Manual page 224

Frequency protection with 8 stages (FRQ/DFRQ)
The frequency protection (FRQ and DFRQ) functions have eight frequency elements (stages)
to detect frequency-deviations and frequency-changes. If the deviations or changes occur, the
FRQ and DFRQ functions issue a trip or alarm signal in response to the degree of the
frequency-deviation/change.
This FRQ function also has rapid change detection (RCD) so that the user can block
excessive FRQ operation when an out of step phenomena occurs.
To simplify the FRQ/DFRQ descriptions, only stage 1 is discussed, but is applicable to the
other stages; hence, read the express for stage 1 as the other stages unless a special
explanation or instruction has been produced.
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6F2T0200 (0.15)
GRE200 (1,2)