GE Multilin 489 Instruction Manual page 141
Generator management relay
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Also See for Multilin 489:
- Instruction manual (306 pages) ,
- Communications manual (78 pages) ,
- Instruction manual (38 pages)
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CHAPTER 5: SETPOINTS
489 GENERATOR MANAGEMENT RELAY – INSTRUCTION MANUAL
Courtesy of NationalSwitchgear.com
IAC Curves
The curves for the General Electric type IAC relay family are derived from the formula:
⎛
B
T
M
×
⎜
A
----------------------------------- -
=
+
(
I I
⁄
⎝
pickup
where: T = Trip Time in seconds
M = Multiplier setpoint
I = Input Current
I
= Pickup Current setpoint
pickup
A, B, C, D, E = Constants
Table 5–4: IAC Inverse Time Curve Constants
IAC Curve Shape
A
Extreme Inverse
0.0040
Very Inverse
0.0900
Inverse
0.2078
Short Inverse
0.0428
FlexCurve™
The custom FlexCurve™ has setpoints for entering times to trip at the following current
levels: 1.03, 1.05, 1.1 to 6.0 in steps of 0.1 and 6.5 to 20.0 in steps of 0.5. The relay then
converts these points to a continuous curve by linear interpolation between data points. To
enter a custom FlexCurve™, read off each individual point from a time overcurrent
coordination drawing and enter it into a table as shown. Then transfer each individual
point to the 489 using either the EnerVista 489 Setup software or the front panel keys and
display.
D
------------------------------------------ -
------------------------------------------ -
+
+
2
) C
(
(
I I
⁄
) C
)
(
(
–
–
pickup
Constants
B
C
0.6379
0.6200
0.7955
0.1000
0.8630
0.8000
0.0609
0.6200
⎞
E
⎟
(EQ 0.6)
3
⎠
I I
⁄
) C
)
–
pickup
D
E
1.7872
0.2461
–1.2885
7.9586
–0.4180
0.1947
–0.0010
0.0221
5–31
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