Power-Off And Magnetic Contactor (Mc) - Mitsubishi Electric FR-F820-00077 Instruction Manual

Precautions for use of the inverter
3.4

Power-OFF and magnetic contactor (MC)

Inverter input side magnetic contactor (MC)
On the inverter input side, it is recommended to provide an MC for the following purposes:
(Refer to page 2-4 for selection.)
● To disconnect the inverter from the power supply at activation of a protective function or at
malfunctioning of the driving system (emergency stop, etc.).
● To prevent any accident due to an automatic restart at power restoration after an inverter stop
made by a power failure.
● To separate the inverter from the power supply to ensure safe maintenance and inspection work.
If using an MC for emergency stop during operation, select an MC regarding the inverter input side
current as JEM1038-AC-3 class rated current.
NOTE Since repeated inrush currents at power ON will shorten the life of the converter circuit (switching
life is about 1,000,000 times), frequent starts and stops of the magnetic contactor must be
avoided. Turn ON/OFF the inverter start controlling terminals (STF, STR) to run/stop the inverter.
Example Inverter start/stop circuit example
As shown below, always use the start signal (ON or OFF of STF(STR) signal) to make a start or stop.
Fig. 3-12:
When the power supply is 400 V class, install a stepdown transformer.
Connect the power supply terminals R1/L11, S1/L21 of the control circuit to the input side of the
MC to hold an alarm signal when the inverter's protective circuit is activated. At this time, remove
jumpers across terminals R/L1 and R1/L11 and S/L2 and S1/L21. (Refer to page 2-58 for removal of
the jumper.)
FR-F800
Power
supply
Operation preparation
OFF ON
MC
Start-/Stop
Start
MC
Stop
RA
Start and stop of the inverter
Power-OFF and magnetic contactor (MC)
MCCB
MC
R/L1
S/L2
T/L3
R1/L11
S1/L21
T
Inverter
MC
RA
STF/STR
PC
RA
U
To the
V
motor
W
C1
B1
A1
I002424E_G
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