489 voltage dependent overload (custom curve) – GE 489 User Manual
Page 112
4-62
489 Generator Management Relay
GE Multilin
4.10 S9 THERMAL MODEL
4 SETPOINTS
4
To illustrate the Voltage Dependent Overload Curve feature, the thermal limits shown in Figure 4–13: Thermal Limits for
High Inertial Load on page 4–61 will be used.
1.
Construct a custom curve for the running overload thermal limit. If the curve does not extend to the acceleration ther-
mal limits, extend it such that the curve intersects the acceleration thermal limit curves. (see CUSTOM CURVE below).
2.
Enter the per unit current value for the acceleration overload curve intersect with the custom curve for 80% voltage.
Also enter the per unit current and safe stall protection time for 80% voltage (see ACCELERATION CURVE below).
3.
Enter the per unit current value for the acceleration overload curve intersect with the custom curve for 100% voltage.
Also enter the per unit current and safe stall protection time for 100% voltage (see ACCELERATION CURVE below)
Figure 4–14: VOLTAGE DEPENDENT OVERLOAD CURVES
489
VOLTAGE DEPENDENT OVERLOAD
(CUSTOM CURVE)
808827A3.CDR
1
1
2
3
4
5
6
7
8
2
3
4
5
6
7
8
9
10
20
30
40
50
60
70
80
90
100
T
IM
E
TO
T
R
IP
(S
E
C
O
N
D
S
)
MULTIPLES OF FULL LOAD AMPS
200
300
400
500
600
700
800
900
1000
Acceleration Intersect at 80%V
Acceleration Intersect at 100%V
GE Multilin
489
VOLTAGE DEPENDENT OVERLOAD
(ACCELERATION CURVES)
808828A3.CDR
1
1
2
3
4
5
6
7
8
2
3
4
5
6
7
8
9
10
20
30
40
50
60
70
80
90
100
T
IM
E
TO
T
R
IP
(S
E
C
O
N
D
S
)
MULTIPLES OF FULL LOAD AMPS
200
300
400
500
600
700
800
900
1000
489 Custom Curve
GE Multilin