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5.6 GROUPED ELEMENTS
If
MOTOR START INHIBIT MARGIN
MOTOR START INHIBIT
(TCU = 100%) or tripped/stopped by any other reason (TC
based on 15% level of thermal capacity. To calculate the thermal lockout time in this case, the following values of TCU
are to be applied to the above equation: TCU
stopped, and TCU
•
VOLTAGE DEPENDENT FUNCTION: If the motor is called upon to drive a high inertia load, it is quite possible and
acceptable for the acceleration time to exceed the safe stall time (keeping in mind that a locked rotor condition is differ-
ent than an acceleration condition). The voltage dependent overload curve feature is tailored to protect these types of
motors. This curve is composed of the three characteristic of thermal limit curve shapes as determined by the stall or
locked rotor condition, acceleration, and running overload. The figure below presents the typical thermal limit curve for
high inertia application.
5
Voltage dependent overload functionality is operational only if the selected
TEM
MOTOR SETUP
NOTE
5-154
is greater than "0", but relay does not contain records for five successful starts, then the
operand can be asserted again either when motor is tripped by thermal protection
start
= 15%.
end
HIGH INERTIA LOAD OVERLOAD CURVES
8800 HP, 13.2 kV, REACTOR COOLANT PUMP
1000
900
800
700
1
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
3
menu) is assigned to a valid three-phase VT.
M60 Motor Protection System
< 100%). However, operand reset is evaluated
accumulated
= thermal capacity accumulated from the moment the motor was
GE Multilin
1- Running Overload Thermal Limit
2- Acceleration Thermal Limit at 80%V
3- Acceleration Thermal Limit at 100%V
4- Locked Rotor Thermal Limit
5- Motor Acceleration Curve at 80% V
6- Motor Acceleration Curve at 100%V
2
3
4
5
6
4
5
6
MULTIPLES OF FULL LOAD AMPS
5 SETTINGS
7
8
806821A4.CDR
(see the
MOTOR LINE SOURCE
GE Multilin
SYS-
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