User Manual Chapter 1
GFK-2749A Jan 2020
PSM Module Description and Specifications 15
PhaseShiftOK = Off @ 15.9º {Angle Delay – Phase_Shift_Thr}
If Sync is requested while PhaseShiftOK = On, then CloseRelayOK will be set to On
for the Angle Delay + 24 cycles. At
Δ
F = 0.09Hz and 60Hz, the PhaseShiftOK window
is 800ms (25.9
⁰
) + 400ms = 1.2 seconds.
Static Phase Angle Synchronization
In static phase angle synchronization, the PSM will set PhaseShiftOK bit between
±Phase_Shift_Thr, regardless of the Delta Frequency (Slip Frequency). This mode is selected
by setting the Breaker Delay hardware configuration parameter to zero.
Figure 7
With no breaker delay information, the PSM reverts to classic synchronization. Either the
control system holds the phase angle within the Phase_Shift_Thr before requesting
Synchronization, or the rate of change of the phase angle and the breaker delay are known
and the control system holds the Delta Frequency (Slip Frequency) at a value calculated to
bring the contacts to closure at or near 0
⁰
phase angle.
ANSI 27 – Under-voltage Protection
This function monitors voltages to detect abnormally low grid voltage. It works with phase
to-phase voltage in delta power systems, or phase-to-neutral voltage in wye power systems.
Each phase voltage is monitored separately. An alarm will be triggered if any voltage falls
below the specified UNDER_VOLT_ THR voltage value for a time period longer than
UNDER_VOLT_DELAY. The alarm Is cleared if any voltage rises above the specified
UNDER_VOLT_ THR voltage value for a time period longer than UNDER_VOLT_DELAY. The
UNDER_VOLT_THR is a percentage of the nominal voltage.
ANSI 32 – Reverse Power Protection
Reverse Power Protection prevents the generator from motoring on loss of the prime
mover. An alarm will be triggered if the prime mover power falls below the REV_PWR_THR
for a time period longer than REV_PWR_ DELAY. The alarm will be cleared when the prime
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