GE MOTOR MANAGER 2, Инструкция по эксплуатации

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4-12 MM2 Motor Manager 2
GE Power Management
4.3 S2 PROTECTION 4 SETPOINTS
4
4.3.4 MOTOR PROTECTION – THERMAL
PATH: SETPOINTS
tt
S2 PROTECTION
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MOTOR PROTECTION THERMAL
For example, given the following motor information: motor FLC = 100 A, actual motor current = 80 A,
LRT Hot = 7 seconds, and LRT Cold = 10 seconds, the thermal capacity used can be determined
from the
HOT/COLD CURVE RATIO as follows:
FULL LOAD CURRENT:
100 A
Range: 5 to 1000 A or OFF, Step 1, for CT PRIMARY > 50 A
0.5 to 100.0 A or OFF, Step 0.1, for CT PRIMARY
≤
50 A
Usually the rated current on the motor nameplate is entered as the full
load current value. A lower value effectively overprotects the motor. It is
not advisable to enter a value higher than the motor nameplate rating.
When the actual motor current exceeds this value, the thermal capacity
starts to be used up and the motor will eventually trip according to the
overload curve selected.
HIGH SPEED FULL LOAD
CURRENT: 100 A
Range: 5 to 1000 A or OFF, Step 1, for
CT PRIMARY
> 50 A
0.5 to 100.0 A or OFF, Step 0.1, for CT PRIMARY
≤
50 A
This setpoint functions the same way as
FULL LOAD CURRENT
, but refers
to the high speed FLC of a two-speed motor, and is only in effect while
contactor B is energized.
OVERLOAD PICKUP
LEVEL: 1.00
Range: 1.00 to 1.25; Step: 0.01
This setpoint dictates where the overload curve begins as the motor
enters an overload condition. This is useful for service factor motors as it
allows the pickup level to be defined. The curve is effectively cut off at
current values below this pickup.
OVERLOAD CURVE
NUMBER: 4
Range: 1 to 8, CLASS 10, CLASS 15, CLASS 20, CLASS 30
Select 1 of 12 different I
2
t time-overcurrent overload curves. Consult the
overload curve figures and tables in this manual (see pages 4–34 to 4–
37) to match the curve number to a particular motor. If no motor curve
data is available, select the curve which has a 6 times overload trip time
equal to the motor nameplate stall time. The MM2 also has four NEMA
class curves which can be selected should these curves be suggested
by the manufacturer.
HOT/COLD CURVE
RATIO: 75
Range: 20 to 100%; Step: 1%
Defines the ratio of motor "hot" thermal characteristic to the motor "cold"
characteristic. It is used to thermally model the heating in the motor
when running at or below full load current. This is often determined from
motor thermal damage curves or Locked Rotor Time Hot and Locked
Rotor Time Cold data.
HOT/COLD CURVE RATIO
determines the thermal
capacity used when a motor has run at its full load current long enough
for the motor temperature to reach its steady state value, which is
defined as the hot temperature. Note that the thermal capacity used is
reduced according to the actual motor current.
HOT/COLD CURVE RATIO
LRT Hot
LRT Cold
-------------------------
100
×
7 sec.
10 sec.
-------------------
100
×
70%
= = =