Application notes
IMGT30017EN 55
Ventilation. The motor ventilation is appropriate for the expected operating speed range. Prolonged low speed operation requires
auxiliary motor cooling (see chart sections 1-2).
Overload. The motor is capable of supplying adequate overload torque over the operating speed range.
Typical curves
(1) Overload torque limited to 1.1 Tn (Rated Torque) in variable torque application.
• For speed greater than base speed, check with the motor manufacturer to verify operation.
• In over speed operations vibrations may occur due to rotor unbalance and load fluctuations.
The motor noise may increase.
•
• Self-excitation of the motor. The phenomenon is highly destructive and dangerous, as it provokes damages to the equipment;
said phenomenon can happen in the event that a LC filter is connected to the inverter output. Verify that the current absorbed by the
capacitor bank of the LC filter at inverter output is less than 90% of the motor no-load current.
Before connecting the inverter to the motor, verify that the current absorbed by the capacitor bank of the LC
filter at inverter output (see the capacity values of the working diagram enclosed to the supply) is less than
90% of the motor no-load current.
It is necessary to verify this condition in order to avoid the possibility of self-excitation of the motor, with
consequent heavy damages both for the equipment and for the operators.
T
ORQUE CAPABILITY VS SPEED
1. S
ELF-VENTILATED MOTOR: PERMANENT
WORKING TORQUE
2. F
ORCED VENTILATED MOTOR: PERMANENT
WORKING TORQUE
O
VERLOAD CAPABILITY VS SPEED
3. O
VERLOAD TORQUE IN THE CONSTANT TORQUE
RANGE
4. O
VERLOAD TORQUE IN THE FIELD-WEAKENING
RANGE
3
4
2
1
T
ORQUE
R
ATED TORQUE
1,75
1,50
1,25
0,95
0,50
0,25
0
1
1 25 50 75 100 50Hz
1 30 60 90 120 60Hz
Base Speed
CAUTION!
WARNING !
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