Mitsubishi Electric FR-A700 Series, Technical Manual

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565
4
P
RACTICAL CIRC
UI
T
S
PRACTICAL CIRCUITS
4.4 Parallel motor operation
(common)
4.4.1 Motors driven by one inverter
(common)
*1 The electronic thermal relay built into the inverter cannot be used. Use an external thermal relay with each motor.
Note that when the capacity is small and the wiring length is large (50m or more), line-to-line leakage currents may operate the
thermal relay. Refer to page 524 and take adequate actions.
Set 0 (A) in the electronic thermal relay parameter to switch off the electronic thermal relay.
*2 How to stop the inverter without switching off the magnetic contactor (MC) when the external thermal relay is actuated:
Use the external thermal input terminal (OH) to cause the inverter to stop the output. (Refer to page 50 for details)
*3 Motor selection
No problem will arise when a specific motor is connected or selected while all motors are at a stop. However, if any of the
motors during a stop is direct-on line started by the contactor etc. during inverter operation, the current limit function of the
inverter may be activated by the starting current of that motor, leading to a sudden change of the output frequency. In this case,
it is recommended to increase the inverter capacity.
*4 Provide a step-down transformer when the power supply is 400V class.
common
common
Motor
IM
U
V
W
R
S
T
MCCB MC
Ground
M
C
F
IM
IM
T
*4
STF
STR
STF
STR
FM
SD1
SD2
10
2
5
FM
SD
10
2
5
B
C
OCR1 OCR2 OCR3 B
C
*1
OCR1
*1
OCR2
*1
OCR3
MC
Fault signal
Power
supply
FR-AX
manual controller
Inverter
Fault signal
ON OFF
Ready
OCR1 OCR2 OCR3
OH
SD