Mitsubishi Electric FR-F700PJ Series Manual page 79

When driving a 400V class motor by the inverter, surge voltages attributable to the wiring constants may occur at the motor terminals,
deteriorating the insulation of the motor. In such a case, consider taking the following measures.
(Under general-purpose motor control)
It is recommended to take either of the following measures.
(1) Rectifying the motor insulation and limiting the PWM carrier frequency according to the wiring length
For the 400V class motor, use an insulation-enhanced motor.
Specifically,
1)Specify the "400V class inverter-driven insulation-enhanced motor". (Mitsubishi standard motors (SF-JR, SB-JR 4-pole) are the 400V
class inverter-driven reinforced insulation models.)
2)For the dedicated motor such as the constant-torque motor and low-vibration motor, use the "inverter-driven, dedicated motor".
3)Set Pr. 72 PWM frequency selection as indicated below according to the wiring length
Pr. 72 PWM frequency selection
(2) Suppressing the surge voltage on the inverter side Connect the surge voltage suppression filter (FR-ASFH/FR-BMF-H) on the inverter
output side.
(Under IPM motor control)
When the wiring length is 30m or longer, use the inverter at the carrier frequency of 2.5kHz (Pr. 72 = "0 to 4").
NOTE
 The surge voltage suppression filter (FR-ASF-H/FR-BMF-H) option cannot be used under IPM motor control, so do
not connect them.
Motor with an attached brake
Use a motor with a brake that has an independent power supply
for the brake. Connect the brake power supply to the power
supply on the input side of the inverter. During the brake
operation (motor at a stop), turn OFF the inverter output using a
terminal assigned for the output stop (MRS). Depending on the
types of brake, a rattling noise may be made by the brake
linings in the low-speed range. This is a normal operation and
not a fault.
Pole changing motor
As this motor differs in rated current from the standard motor,
confirm the maximum current of the motor and select the
inverter. Be sure to change the number of poles after the motor
has stopped. If the number of poles is changed during rotation,
the regenerative overvoltage protection circuit may be activated
to cause an inverter alarm, coasting the motor to a stop.
Submersible motor
The rated motor current is larger than that of the standard
motor. Caution is required to ensure proper selection of the
inverter capacity. The distance of wiring between the motor and
the inverter tends to be longer. Use thick enough cables for
wiring according to the recommendation in page 68. Compared
to a motor for not submersed use, the leakage current tends to
be increased. Caution is required to ensure proper selection of
an earth leakage circuit breaker.
Inverter-driven 400V class motor
Wiring Length
50m or less 50m to 100m
15(14.5kHz) or less 8(8kHz) or less
Application to special motors
exceeding 100m
2(2kHz) or less
Explosion-proof motor
To drive a pressure and explosion-proof motor, the explosion-
proof test is required for the combination of motor and inverter.
The explosion-proof test is also required for driving the existing
explosion-proof motors. The FR-B and FR-B3 series inverters,
which have passed the explosion-proof test, are also available.
Please consult separately for details. The inverter body is not
explosion proof. Install it in a non-hazardous place.
Geared motor
The continuous operating rotation range of this motor changes
depending on the lubrication system and maker. Especially in
the case of oil lubrication, continuous operation in the low speed
range only can cause gear seizure. For fast operation at higher
than 60Hz, please consult the maker.
Synchronous motor other than a
dedicated IPM motor
This motor is not suitable for applications of large load variation
or impact, where out-of-sync is likely to occur. Please contact us
when using this motor because its starting current and rated
current are greater than those of the standard motor and will not
rotate stably at low speed.
Single-phase motor
Single-phase motors are not suitable for variable-speed
operation with an inverter.
With the capacitor starting system, a harmonic current flows into
the capacitor and the capacitor may be damaged. With the split-
phase starting or repulsion starting system, the motor cannot
generate sufficient output torque in the low-speed range and
furthermore, the internal centrifugal switch does not operate,
resulting in burnout of the starting coil. Replace the motor by a
three-phase motor.
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