Reverse Power - GE 750 Instruction Manual

S5 Protection

Reverse Power

REVERSE
POWER
NOTE
GE Multilin
PATH: SETPOINTS S5 PROTECTION
[ ] REVERSE POWER
FUNCTION: Disabled
REVERSE POWER
MESSAGE
RELAYS (3-7): -----
REVERSE POWER
MESSAGE
PICKUP: 0.050 xRATED
REVERSE POWER
MESSAGE
DELAY:
A Reverse Power element is generally associated with generator protection. Such an
element is used to detect loss of mechanical power coming into the turbine and to
trip the unit to prevent turbine blade heating or other adverse effects in turbo-
generator sets. The
REVERSE POWER PICKUP
can measure, but no higher than one-half the electrical power required to motor the
generator with total loss of mechanical power. The Reverse Power element is not
normally used in conventional feeder protection applications.
The Reverse Power element generates an output when the three-phase reverse real
power is greater than the
REVERSE POWER PICKUP
to 1 second or higher to avoid problems with power
REVERSE POWER DELAY
oscillations that may be experienced on synchronization; a setting in the range of 10
to 15 seconds is typical. Recall that the rated power is calculated as follows:
Rated Power 3 V ×
=
sec(line-line)
The sensitivity of this element and the requirement to have two times pickup limits
its range of application. The motoring power cannot be less that 3% of rated, and
the angle away from the 180° angle of maximum sensitivity should not be greater
than ±85 to 87° due to reactive loading on the generator.
This element is optional and available from GE Multilin as Mod 008. To order, please
contact the factory with the serial number of the 750/760 relay. Refer to Reverse
Power on page 8–1 for the complete procedure for installing and verifying the
Reverse Power element.
FIGURE 5–35: Reverse Power Logic
http://www.GEmultilin.com
Feeder Management Relay
REVERSE POWER
Range: Disabled, Trip, Alarm, Control
Range: Any combination of 3 to 7
Auxiliary relays
Range: 0.015 to 0.600 x RATED in steps
of 0.001
Range: 0.0 to 6000.0 s in steps of 0.1
10.0 s
setting is usually set as low as the relay
setting. It is recommended to set
× VT Ratio I × × CT Ratio
sec(rated)
750/760
(EQ 5.18)
5–73