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Power-off and magnetic contactor (MC)
2.5 Power-off and magnetic contactor (MC)
(1) Inverter input side magnetic contactor (MC)
On the inverter input side, it is recommended to provide an MC for the following purposes.
(
for selection.))
page
Refer to
3
1) To release the inverter from the power supply when the inverter's protective function is activated or when the drive is
not functioning (e.g. emergency stop operation).
2) To prevent any accident due to an automatic restart at restoration of power after an inverter stop made by a power failure
3) The control power supply for inverter is always running and consumes a little power. When stopping the inverter for an
extended period of time, powering off the inverter will save power slightly.
4) To separate the inverter from the power supply to ensure safe maintenance and inspection work
The inverter's input side MC is used for the above purpose, select class JEM1038-AC3MC for the inverter input side
current when making an emergency stop during normal operation.
REMARKS
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 MC must be avoided. Turn on/off the inverter start controlling terminals (STF, STR) to run/stop the
inverter.
Power
supply
Operation preparation
OFF
ON
MC
Start/Stop
MC
Operation
Stop
RA
(2) Handling of the inverter output side magnetic contactor
Switch the magnetic contactor between the inverter and motor only when both the inverter and motor are at a stop.
When the magnetic contactor is turned on while the inverter is operating, overcurrent protection of the inverter and
such will activate. When an MC is provided to switch to a commercial power supply, for example, it is recommended to
use commercial power supply-inverter switchover operation Pr. 135 to Pr. 139 (
24
MCCB
MC
R/L1
S/L2
T/L3
R1/L11
S1/L21
T
*1
Inverter
MC
RA
STF(STR)
PC
RA
• Inverter start/stop circuit example
U
As shown on the left, always use the start signal
To the
(ON or OFF across terminals STF or STR-PC) to
V
motor
make a start or stop.
W
*1 When the power supply is 400V class, install a step-
down transformer.
*2
*2 Connect the power supply terminals R1/L11, S1/L21
of the control circuit to the primary side of the MC to
hold an alarm signal when the inverter's protective
circuit is activated. At this time, remove jumpers
C1
across terminals R/L1-R1/L11 and S/L2-S1/L21.
B1
(Refer to page 18 for removal of the jumper.)
A1
Instruction Manual (applied)).
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