S2 Protection; Motor Protection : Thermal - GE Multilin MM3 Motor Manager 3 Instruction Manual

CHAPTER 5: SETPOINTS
5.3.1 Motor
Protection:
Thermal
] MOTOR PROTECTION
] THERMAL
MM3 MOTOR MANAGER 3 – INSTRUCTION MANUAL
5.3

S2 Protection

PATH: S2 PROTECTION MOTOR PROTECTION THERMAL
The motor protection (thermal) settings are programmed as follows:
• FULL LOAD CURRENT: 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: This setpoint functions the same way as
, but refers to the high speed full load current (FLC) of a two-speed
LOAD CURRENT
motor, and is only in effect while contactor B is energized.
• OVERLOAD PICKUP LEVEL: 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: Select 1 of 12 different I
curves. Consult the overload curve figures and tables below 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
MM3 Motor Manager 3 also has four NEMA class curves which can be selected should
these curves be suggested by the manufacturer.
• HOT/COLD CURE RATIO: 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. The
HOT/COLD CURVE RATIO
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.
FULL LOAD CURRENT:
OFF
HIGH SPEED FULL LOAD
CURRENT: 100 A
OVERLOAD PICKUP
LEVEL: 1.00
OVERLOAD CURVE
NUMBER: 4
HOT/COLD CURVE
RATIO: 75%
determines the thermal capacity used when a motor has run
S2 PROTECTION
Range: 0.1 to 1000.0 A or OFF in steps
of 0.1
Range: 0.1 to 1000.0 A or OFF in steps
of 0.1
Range: 1.00 to 1.25 in steps of 0.01
Range: 1 to 8, Class 10, Class 15,
Class 20, Class 30
Range: 20 to 100% in steps of 1
FULL
2
t time-overcurrent overload
5–11