GE Power Management
469 Motor Management Relay
4-39
4 SETPOINT PROGRAMMING
4.6 S5 THERMAL MODEL
4
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 @ 100% voltage and multiply-
ing by 1.10. For trip times above the 110% current level, the trip time of 110% will be used. (see figure below).
Figure 4–13: 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.
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
HIGH INERTIA LOAD OVERLOAD CURVES
8800 HP, 13.2 kV, REACTOR COOLANT PUMP
TIME
T
O
TRIP
(SECONDS)
MULTIPLES OF FULL LOAD AMPS
200
300
400
500
600
700
800
900
1000
Acceleration Intersect @ 80%V
Custom Curve
Acceleration Intersect @ 100%V
Safe Stall Time @ 80%V,
80%V Stall Current
Safe Stall Time @ 100%V,
100%V Stall Current
Safe Stall Points
Extrapolated to 110%V
806824A3.CDR
GE Power Management
GE Power Management
NOTE
