GE P24DM - Reverse Power Protection; Reverse Power Implementation

2 REVERSE POWER PROTECTION
When a power supply failure occurs on the feeder, synchronous motors become generators due to the inertia of
their load and induction motor
s become generators.
The aim of the reverse power protection is to detect the inverse flow of energy and to ensure that the motor does
not feed the fault which has appeared on the network.
The Reverse Power protection in the P24DM has a single reverse power threshold Rev P< Power Set. If this setting
is reached, the reverse power protection trips in a time equal to the time delay setting Rev P< Time Delay. A drop-
off time, Rev P< Drop-of Ti during the motor start time can be used to avoid tripping orders during starts.
Trip Rev. Power indicates the trip of the reverse power protection. This signal is used to operate the output relays
and trigger the disturbance recorder as programmed into the programmable Scheme Logic (PSL). The state of the
DDB signals can also be programmed to be viewed in COMMISSION TESTS > Monitor Bit x.
This feature is only enabled when the circuit breaker is closed, therefore it requires a 52a circuit breaker auxiliary
contact mapped to an opto input to obtain the CB closed / CB open information.
2.1 REVERSE POWER IMPLEMENTATION
Reverse power Protection is implemented in the P
OWER PROTECTION column of the relevant settings group, under
the sub-heading REVERSE POWER.
The reverse power protection element provides 1 stage of directional reverse power.
The Start and Trip timer resets if the power falls below the drop-off level or if an inhibit condition occurs. The reset
mechanism is similar to the overcurrent functionality for a pecking fault condition, where the percentage of
elapsed time for the operate timer is memorised for a set reset time delay. If the Start condition returns before the
reset timer has timed out, the operate time initialises from the memorised travel value. Otherwise the memorised
value is reset to zero after the reset time times out.
Chapter 12 - Power Protection Functions P24xM
240 P24xM-TM-EN-2.1