Countermeasures against deterioration of the 400 V class motor insulation
92
PRECAUTIONS FOR USE OF THE INVERTER
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
(With induction motor)
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.
• Suppressing the surge voltage on the inverter side
- For the FR-A840-01800(55K) or lower, connect the surge voltage suppression filter (FR-ASF-H/FR-BMF-H) to the output
side.
- For the FR-A840-02160(75K) or higher, connect the sine wave filter (MT-BSL/BSC) to the output side.
(With PM motor)
• When the wiring length exceeds 50 m, set "9" (6 kHz) or less in Pr.72 PWM frequency selection.
NOTE
• For the details of Pr.72 PWM frequency selection, refer to page 277. (When using an optional sine wave filter (MT-BSL/
BSC), set "25" (2.5 kHz) in Pr.72.)
• For the details of the surge voltage suppression filter (FR-ASF-H/FR-BMF-H) and the sine wave filter (MT-BSL/BSC), refer to
the Instruction Manual of each option.
• A surge voltage suppression filter (FR-ASF-H/FR-BMF-H) can be used under V/F control and Advanced magnetic flux vector
control.
A sine wave filter (MT-BSL/BSC) can be used under V/F control. Do not use the filters under different control modes.
• The carrier frequency is limited during PM sensorless vector control.(Refer to page 277.)
Wiring length
50 m or shorter 50 m to 100 m Longer than 100 m
Pr.72 PWM frequency selection 15 (14.5 kHz) or lower 9 (9 kHz) or lower 4 (4 kHz) or lower
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