GE 469 Instruction Manual page 87

4 SETPOINTS
The 469 takes the information provided and create protection curves for any voltage between the minimum and 100%. For
values above the voltage in question, the 469 extrapolates the safe stall protection curve to 110% voltage. This current
level is calculated by taking the locked rotor current at 100% voltage and multiplying by 1.10. For trip times above the 110%
current level, the trip time of 110% will be used. (see figure below).
1000
900
800
700
600
500
400
300
200
100
90
80
70
60
50
40
30
20
10
9
8
7
6
5
4
3
2
Figure 4–10: VOLTAGE DEPENDENT OVERLOAD PROTECTION CURVES
The safe stall curve is in reality a series of safe stall points for different voltages. For a given voltage, there
can only be one value of stall current and therefore, only one safe stall time.
NOTE
GE Multilin
Courtesy of NationalSwitchgear.com
HIGH INERTIA LOAD OVERLOAD CURVES
8800 HP, 13.2 kV, REACTOR COOLANT PUMP
Custom Curve
1
1 2 3
MULTIPLES OF FULL LOAD AMPS
469 Motor Management Relay
GE Multilin
Acceleration Intersect at 80%V
Acceleration Intersect at 100%V
Safe Stall Time at 80%V,
80%V Stall Current
Safe Stall Time at 100%V,
100%V Stall Current
Safe Stall Points
Extrapolated to 110%V
4 5 6
4.6 S5 THERMAL MODEL
7 8
806824A4.CDR
4-37
4