GE PACSystems RX3i User Manual page 23

ANSI 27 – Under-voltage Protection
ANSI 32 – Reverse Power Protection
ANSI 47 – Voltage Phase Sequence Protection
ANSI 50 – Instantaneous Over-current Protection
ANSI 59 – Over-voltage Protection
ANSI 60 – Voltage (current) Imbalance
GFK-2749
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.
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 mover power rises above the REV_PWR_THR for a time period
longer than REV_PWR_ DELAY. The REV_PWR_THR is a percentage of the nominal
power which, in a 3-phase system, is three times the nominal voltage multiplied by the
nominal current.
The sequence of the phase A, B and C voltages is monitored. Detection of a wrong
sequence (A, C, B for example) will trigger an alarm.
Provides three-phase protection against overloads and phase-to-phase short-circuits. The
alarm will be triggered if any phase current exceeds the specified OVER_CURR_ THR
voltage value for a time period longer than OVER_CURR_DELAY. The
OVER_CURR_THR is a percentage of the nominal current.
This provides detection of abnormally high phase voltage. It works with phase-to-phase
voltage in Delta power systems, or phase-to-neutral voltage in WYE Power systems. Each
voltage is monitored separately. An alarm will be triggered if any voltage exceeds the
specified OVER_VOLT_THR value, as a percentage of the Nominal Voltage parameter,
for a time period longer than OVER_VOLT_DELAY. This alarm is cleared when the
voltage drops below the OVER_VOLT_THR value for a time period longer than the
OVER_VOLT_DELAY. The OVER_VOLT_THR is a percentage of the nominal voltage.
An alarm will be triggered if any phase voltage or current reading varies from the average
of all three phases by more than VI_IMBALANCE_THR for a time period longer than
VI_IMBALANCE_DELAY. The alarm is cleared when the imbalance condition is corrected
for a time period longer than VI_IMBALANCE_DELAY. IV_IMBALANCE_THR is a
percentage of the average of the three phase voltages (for voltage imbalance) or the three
phase currents (for current imbalance) on a given grid. It works with phase-to-phase
voltage in Delta power systems, or phase-to-neutral voltage in WYE Power systems. No
comparison is performed between the two grids. Neutral current is not monitored for
imbalance.
Chapter 1 PSM Module Description and Specifications
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