Mitsubishi Electric FR-F820-04750 Instruction Manual page 122

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Table of Contents

Power-OFF and magnetic contactor (MC)

Handling of the magnetic contactor on the inverter's output side

Switch the magnetic contactor between the inverter and motor only when both the inverter and mo-

tor are at a stop. When the magnetic contactor is turned ON while the inverter is operating, overcur-

rent protection of the inverter and such will activate. When an MC is provided to switch to a commer-

cial power supply, for example, it is recommended to use the electronic bypass function Pr. 35 to Pr.

139 (refer to page 5-327). (The commercial power supply operation is not available with PM motors.)

Handling of the manual contactor on the inverter's output side

A PM motor is a synchronous motor with high-performance magnets embedded inside. High-voltage

is generated at the motor terminals while the motor is running even after the inverter power is turned

OFF. In an application where the PM motor is driven by the load even after the inverter is powered

OFF, a low-voltage manual contactor must be connected at the inverter's output side.

Before wiring or inspection for a PM motor, confirm that the PM motor is stopped. In an applica-

tion, such as fan and blower, where the motor is driven by the load, a low-voltage manual contac-

tor 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).

Precautions for use of the inverter