GE 469 Instruction Manual page 194

Note
5–52
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% voltage 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
1
1 2
FIGURE 5–11: 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.
GE Multilin
HIGH INERTIA LOAD OVERLOAD CURVES
8800 HP, 13.2 kV, REACTOR COOLANT PUMP
Custom Curve
Acceleration Intersect at 80%V
Acceleration Intersect at 100%V
3 4 5
MULTIPLES OF FULL LOAD AMPS
469 MOTOR MANAGEMENT RELAY – INSTRUCTION MANUAL
CHAPTER 5: SETTINGS
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
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806824A4. DR