xii
Geared motors
If the power transmission mechanism uses an oil-lubricated
gearbox or speed changer/reducer, then continuous motor
operation at low speed may cause poor lubrication. Avoid
such operation.
Synchronous mo-
tors
It is necessary to take special measures suitable for this
motor type.
For details about the PMSM drive, refer to Chapter 5,
Section 5.3 "Notes in Driving PMSM."
In running
special
motors
Single-phase
motors
Single-phase motors are not suitable for inverter-driven
variable speed operation. Use three-phase motors.
* Even if a single-phase power supply is available, use a
three-phase motor as the inverter provides three-phase
output.
Environ-
mental
conditions
Installation loca-
tion
The heat sink and braking resistor of the inverter may be-
come hot under certain operating conditions, so install the
inverter on nonflammable material such as metal.
Ensure that the installation location meets the environmental
conditions specified in Chapter 2, Section 2.1 "Operating
Environment."
Installing an
MCCB or
RCD/ELCB
Install a recommended molded case circuit breaker (MCCB)
or residual-current-operated protective device (RCD)/earth
leakage circuit breaker (ELCB) (with overcurrent protection)
in the input (primary) circuit of the inverter to protect the
wiring. Do not use the circuit breaker capacity exceeding the
recommended rated current.
Installing an MC
in the secondary
circuit
If a magnetic contactor (MC) is mounted in the inverter's
secondary circuit for switching the motor to commercial
power or for any other purpose, ensure that both the inverter
and the motor are completely stopped before you turn the MC
on or off.
Do not connect a magnet contactor united with a surge killer
to the inverter's secondary circuit.
Installing an MC
in the primary
circuit
Do not turn the magnetic contactor (MC) in the input (primary)
circuit on or off more than once an hour as an inverter failure
may result.
If frequent starts or stops are required during motor opera-
tion, use
FWD
/
REV
signals or the
/
keys.
Combina-
tion with
peripheral
devices
Protecting the
motor
The electronic thermal function of the inverter can protect the
motor. The operation level and the motor type (gen-
eral-purpose motor, inverter motor) should be set. For
high-speed motors or water-cooled motors, set a small value
for the thermal time constant and protect the motor.
If you connect the motor thermal relay to the motor with a
long wire, a high-frequency current may flow into the wiring
stray capacitance. This may cause the relay to trip at a cur-
rent lower than the set value for the thermal relay. If this
happens, lower the carrier frequency or use the output circuit
filter (OFL).
