Countermeasures Against Deterioration Of The 400 V Class Motor Insulation - Mitsubishi Electric 800 Series Instruction Manual

3.5
Countermeasures against deterioration of the 400
V class motor insulation
In the PWM type inverter, a surge voltage attributable to wiring constants is generated at the motor terminals. Especially in a
400 V class motor, the surge voltage may deteriorate the insulation. When the 400 V class motor is driven by the inverter,
consider the following countermeasures:
 Countermeasures
It is recommended to take one of the following countermeasures:
 Rectifying the motor insulation and limiting the PWM carrier frequency according to the wiring
length
For the 400 V class motor, use an insulation-enhanced motor.
Specifically,
• Order a "400 V class inverter-driven insulation-enhanced motor".
• For the dedicated motor such as the constant-torque motor and low-vibration motor, use an "inverter-driven dedicated
motor".
• Set Pr.72 PWM frequency selection as indicated below according to the wiring length.
Pr.72 PWM frequency selection
 Suppressing the surge voltage on the inverter side
• Connect the surge voltage suppression filter (FR-ASF-H/FR-BMF-H) to the output side of the inverter.
NOTE
• For the details of the surge voltage suppression filter (FR-ASF-H/FR-BMF-H), refer to the Instruction Manual of each option.
102
3. Precautions for Use of the Inverter

3.5 Countermeasures against deterioration of the 400 V class motor insulation

Shorter than 50 m
14.5 kHz or less
Wiring length
50 to 100 m
8 kHz or less
Longer than 100 m
2 kHz or less