Loss Of Excitation - GE Multilin 489 Instruction Manual

CHAPTER 5: SETPOINTS
5.7.9

Loss of Excitation

1 LOSS OF
EXCITATION
Note
489 GENERATOR MANAGEMENT RELAY – INSTRUCTION MANUAL
Courtesy of NationalSwitchgear.com
PATH: SETPOINTS S6 VOLTAGE ELEM.
[ ] ENABLE VOLTAGE
SUPERVISION: Yes
VOLTAGE
MESSAGE
LEVEL: 0.70 x Rated
CIRCLE 1
MESSAGE
TRIP: Off
ASSIGN CIRCLE 1 TRIP
MESSAGE
RELAYS (1-4): 1---
CIRCLE 1
MESSAGE
DIAMETER: 25.0 Ωsec
CIRCLE 1
MESSAGE
OFFSET: 2.5 Ωsec
CIRCLE 1 TRIP
MESSAGE
DELAY: 5.0 s
CIRCLE 2
MESSAGE
TRIP: Off
ASSIGN CIRCLE 2 TRIP
MESSAGE
RELAYS (1-4): 1---
CIRCLE 2
MESSAGE
DIAMETER: 35.0 Ωsec
CIRCLE 2
MESSAGE
OFFSET: 2.5 Ωsec
CIRCLE 2 TRIP
MESSAGE
DELAY: 5.0 s
The setpoint is seen only if
VOLTAGE LEVEL
Loss of excitation is detected with an impedance element. When the impedance falls
within the impedance circle for the specified delay time, a trip will occur if it is enabled.
Circles 1 and/or 2 can be tuned to a particular system. The larger circle diameter should be
set to the synchronous reactance of the generator, x
generator transient reactance x'
time with a diameter set to 0.7x
supervision is enabled and the generator voltage is above the
The trip feature is supervised by minimum current of 0.05 × CT. Note that the Loss of
Excitation element will be blocked if there is a VT fuse failure or if the generator is offline.
Also, it uses output CT inputs.
The secondary phase-phase loss of excitation impedance is defined as:
Z
loe
where: Z = secondary phase-to-phase loss of excitation impedance
loe
M ∠θ = Secondary impedance phasor (magnitude and angle)
loe loe
LOSS OF EXCITATION
Range: Yes, No
Range: 0.70 to 1.00 × Rated in steps of
Range: Off, Latched, Unlatched
Range: Any combination of Relays 1 to
Range: 2.5 to 300.0 Ωsec in steps of 0.1
Range: 1.0 to 300.0 Ωsec in steps of 0.1
Range: 0.1 to 10.0 s in steps of 0.1
Range: Off, Latched, Unlatched
Range: Any combination of Relays 1 to
Range: 2.5 to 300.0 Ωsec in steps of 0.1
Range: 1.0 to 300.0 Ωsec in steps of 0.1
Range: 0.1 to 10.0 s in steps of 0.1
ENABLE VOLTAGE SUPERVISION
, and the circle offset to the
d
/ 2. Typically the smaller circle (if used) is set to minimum
d
and an offset of x' / 2. This feature is blocked if voltage
d d
V
AB
M ∠ θ
------------- -
= =
loe loe
I I
–
A B
0.01
4
4
is set to "Yes".
setpoint.
VOLTAGE LEVEL
(EQ 5.26)
5–55