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Appendix
Using Inverter for Special Motors
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Pole-changing Motor
The rated input current of pole-changing motors differs from that of standard motors. Select, there-
fore, an appropriate Inverter according to the maximum input current of the motor to be used.
Before changing the number of poles, always make sure that the motor has stopped.
Otherwise, the overvoltage protective or overcurrent protective mechanism will be actuated, resulting
in an error.
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Submersible Motor
The rated input current of submersible motors is higher than that of standard motors. Therefore,
always select an Inverter by checking its rated output current.
When the distance between the motor and Inverter is long, use a cable thick enough to connect the
motor and Inverter to prevent motor torque reduction.
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Explosion-proof Motor
When an explosion-proof motor or increased safety-type motor is to be used, it must be subject to an
explosion-proof test in conjunction with the Inverter.
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Gear Motor
The speed range for continuous operation differs according to the lubrication method and motor
manufacturer. In particular, the continuous operation of an oil-lubricated motor in the low speed
range may result in seizing. If the motor is to be operated at a speed higher than 60 Hz, consult with
the manufacturer.
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Synchronous Motor
A synchronous motor is not suitable for Inverter control.
If a group of synchronous motors is individually turned on and off, synchronism may be lost.
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Single-phase Motor
Do not use the Inverter for a single-phase motor.
The motor must be replaced with a 3-phase motor.
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Power Transmission Mechanism (Speed Reducers, Belts, and Chains)
If an oil-lubricated gear box or speed reducer is used in the power transmission mechanism, oil lubri-
cation will be affected when the motor operates only in the low speed range. The power transmission
mechanism will make noise and experience problems with service life and durability if the motor is
operated at a speed higher than 60 Hz.
7-10
Chapter 7
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