GE Multilin 489 User Manual

CHAPTER 5: SETPOINTS
489 GENERATOR MANAGEMENT RELAY – INSTRUCTION MANUAL 5–55
5.7.9 Loss of Excitation
PATH: SETPOINTS ZV S6 VOLTAGE ELEM. ZV LOSS OF EXCITATION
Note
The VOLTAGE LEVEL setpoint is seen only if ENABLE VOLTAGE SUPERVISION is set to “Yes”.
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
d
, and the circle offset to the
generator transient reactance x’
d
/ 2. Typically the smaller circle (if used) is set to minimum
time with a diameter set to 0.7x
d
and an offset of x’
d
/ 2. This feature is blocked if voltage
supervision is enabled and the generator voltage is above the VOLTAGE LEVEL setpoint.
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:
(EQ 5.26)
where: Z
loe
= secondary phase-to-phase loss of excitation impedance
M
loe
∠θ
loe
= Secondary impedance phasor (magnitude and angle)
1 LOSS OF [Z]
EXCITATION
ENABLE VOLTAGE
SUPERVISION: Yes
Range: Yes, No
MESSAGE
VOLTAGE
LEVEL: 0.70 x Rated
Range: 0.70 to 1.00 × Rated in steps of
0.01
MESSAGE
CIRCLE 1
TRIP: Off
Range: Off, Latched, Unlatched
MESSAGE
ASSIGN CIRCLE 1 TRIP
RELAYS (1-4): 1---
Range: Any combination of Relays 1 to
4
MESSAGE
CIRCLE 1
DIAMETER: 25.0 Ωsec
Range: 2.5 to 300.0 Ωsec in steps of 0.1
MESSAGE
CIRCLE 1
OFFSET: 2.5 Ωsec
Range: 1.0 to 300.0 Ωsec in steps of 0.1
MESSAGE
CIRCLE 1 TRIP
DELAY: 5.0 s
Range: 0.1 to 10.0 s in steps of 0.1
MESSAGE
CIRCLE 2
TRIP: Off
Range: Off, Latched, Unlatched
MESSAGE
ASSIGN CIRCLE 2 TRIP
RELAYS (1-4): 1---
Range: Any combination of Relays 1 to
4
MESSAGE
CIRCLE 2
DIAMETER: 35.0 Ωsec
Range: 2.5 to 300.0 Ωsec in steps of 0.1
MESSAGE
CIRCLE 2
OFFSET: 2.5 Ωsec
Range: 1.0 to 300.0 Ωsec in steps of 0.1
MESSAGE
CIRCLE 2 TRIP
DELAY: 5.0 s
Range: 0.1 to 10.0 s in steps of 0.1
Z
loe
V
AB
I
A
I
B
–
-------------- M
loe
θ
loe
∠==
Courtesy of NationalSwitchgear.com

GE Multilin 489 Specifications

General

Brand	GE
Model	Multilin 489
Category	Relays
Language	English