GE 469

5–52 469 MOTOR MANAGEMENT RELAY – INSTRUCTION MANUAL
CHAPTER 5: SETTINGS
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).
FIGURE 5–11: Voltage Dependent Overload Protection Curves
Note
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.
1
123 4567 8
2
3
4
5
6
7
8
9
10
20
30
40
50
60
70
80
90
100
HIGH INERTIA LOAD OVERLOAD CURVES
8800 HP, 13.2 kV, REACTOR COOLANT PUMP
TIME TO TRIP (SECONDS)
MULTIPLES OF FULL LOAD AMPS
200
300
400
500
600
700
800
900
1000
Acceleration Intersect at 80%V
Custom Curve
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
806824A4.CDR
GE Multilin