Countermeasures Against Deterioration Of The 600 V Class Motor Insulation - Mitsubishi Electric F800-E Series Instruction Manual

Countermeasures against deterioration of the 600 V class motor insulation

NOTE
• Before wiring or inspection for a PM motor, confirm that the PM motor is stopped. In an application, such as fan and blower,
where the motor is driven by the load, a low-voltage manual contactor must be connected at the inverter's output side, and
wiring and inspection must be performed while the contactor is open. Otherwise you may get an electric shock.
• Do not open or close the contactor while the inverter is running (outputting).
3.5
Countermeasures against deterioration of
the 600 V class motor insulation
In the PWM type inverter, a surge voltage attributable to wiring constants is generated at the motor terminals.
Especially for a 600V class motor, the surge voltage may deteriorate the insulation.
Surge voltage at a motor terminal by motor wiring length (reference)
When the 600V class motor is driven by the inverter, consider the following measures:
Measures
• Inverter duty motor
Select an inverter duty motor. Many motor manufacturers sell motors with insulation systems designed to withstand the
stress imposed by PWM inverters
• AC reactor
For added protection, install an AC reactor on the inverter output
200
150
100%
0
10 20 30 40
Motor wiring length (m)
PRECAUTIONS FOR USE OF THE INVERTER
50 60 70 80 90 100
3
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