Omron VS mini J7 User Manual page 175

Using the Inverter for a Motor
H Using Inverter for Special Motors
Pole-changing Motor
Submersible Motor
Explosion-proof Motor
Gearmotor
Synchronous Motor
Single-phase Motor
Power Transmission Mechanism (Speed Reducers, Belts, and Chains)
Motor Burnout Caused by Insufficient Dielectric Strength of Each Phase of Motor
The rated input current of pole-changing motors differs from that of standard
motors. Select, therefore, 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.
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.
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.
This is also applicable when an existing explosionproof motor is to be
operated with the Inverter.
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 burning. If the motor
is to be operated at a speed higher than 60 Hz, consult with the manufacturer.
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.
Do not use the Inverter for a single-phase motor.
The motor should be replaced with a 3-phase motor.
If an oil-lubricated gear box or speed reducer is used in the power
transmission mechanism, oil lubrication 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.
Surge occurs among the phases of the motor when the output voltage is
switched.
If the dielectric strength of each phase of the motor is insufficient, the motor
may burn out.
The dielectric strength of each phase of the motor must be higher than the
maximum surge voltage. Normally, the maximum surge voltage is
approximately three times the power voltage imposed on the Inverter.
Chapter 11
161