Mitsubishi Electric MELSERVO-J3 Series Handbook page 205

Part 5: Review on Replacement of MR-J3-DU_ with MR-J4-DU_
When the converter unit receives a start command from the drive unit, CNP1-2 and L21 are shorted, and
the control circuit power is supplied to the magnetic contactor. When the control circuit power is
supplied, the magnetic contactor is turned on, and the main circuit power is supplied to the converter
unit.
In the following cases, CNP1-2 and L21 in the converter unit are opened, and the main circuit power
supply is automatically shut off.
(a) An alarm has occurred in the converter unit.
(b) An alarm has occurred in the drive unit.
(c) The EM1 (forced stop) of the converter unit was turned off.
(d) [AL. 95 STO warning] has occurred in the drive unit (J4 series).
(2) When magnetic contactor drive output is disabled
The main circuit power supply is not automatically shut off even when an alarm occurs in the resistance
regeneration converter unit or the drive unit. Therefore, configure an external circuit to shut off the main
circuit power supply when detecting an alarm.
5 - 10