GE 489 - Page 96

4-58 489 Generator Management Relay
GE Power Management
4.10 S9 THERMAL MODEL 4 SETPOINT PROGRAMMING
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 4–57 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
808827A2.CDR
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123 45678
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TIME TO TRIP (SECONDS)
MULTIPLES OF FULL LOAD AMPS
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Acceleration intersect @ 80% V
Acceleration Intersect @ 100% V
489
VOLTAGE DEPENDENT OVERLOAD
(CUSTOM CURVE)
GE Power Management
808828A2.CDR
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123 45678
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TIME TO TRIP (SECONDS)
MULTIPLES OF FULL LOAD AMPS
200
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1000
489 Custom Curve
489
VOLTAGE DEPENDENT OVERLOAD
(ACCELERATION CURVES)
GE Power Management