Countermeasures Against Deterioration Of The 400 V Class Motor Insulation - Mitsubishi Electric A800 Plus Instruction Manual

Countermeasures against deterioration of the 400 V class motor insulation

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
- If the motor capacity is 280 kW or lower, connect the sine wave filter (MT-BSL/BSC) to the output side.
NOTE
• When using the optional sine wave filter (MT-BSL/BSC), set Pr.72="25" (2.5 kHz).
• For the details of the sine wave filter (MT-BSL/BSC), refer to the Instruction Manual of each option.
• A sine wave filter (MT-BSL/BSC) can be used under V/F control. Do not use the filters under different control methods.
84
PRECAUTIONS FOR USE OF THE INVERTER
Wiring length
100 m or shorter
6 (6 kHz) or lower 4 (4 kHz) or lower
Longer than 100 m