Precautions For Use Of The Inverter - Mitsubishi Electric FR-F840-00023 Installation Manuallines

4 PRECAUTIONS FOR USE OF THE INVERTER

The FR-F800 series is a highly reliable product, but incorrect peripheral circuit making or operation/handling method may
shorten the product life or damage the product.
Before starting operation, always recheck the following items:
Use crimping terminals with insulation sleeve to wire the power supply and motor.
Application of power to the output terminals (U, V, W) of the inverter will damage the inverter. Never perform such wiring.
After wiring, wire offcuts must not be left in the inverter.
Wire offcuts can cause an alarm, failure or malfunction. Always keep the inverter clean. When drilling mounting holes in
a control box etc., take care not to allow chips and other foreign matter to enter the inverter.
Use cables of the appropriate size to make a voltage drop of 2% maximum.
If the wiring distance is long between the inverter and motor, a voltage drop in the main circuit will cause the motor
torque to decrease especially at the output of a low frequency.
Refer to page 14 for the recommended cable size.
The overall wiring length should be within the prescribed length.
Especially for long distance wiring, the fast-response current limit function may be reduced or the equipment connected
to the inverter output side may malfunction or become faulty under the influence of a charging current due to the stray
capacity of the wiring. Therefore, note the overall wiring length. (Refer to page 18.)
Electromagnetic wave interference
The input/output (main circuit) of the inverter includes high frequency components, which may interfere with the
communication devices (such as AM radios) used near the inverter. In this case, activate the EMC filter (turn ON the
EMC filter ON/OFF connector) to minimize interference. (Refer to the Instruction Manual.)
Electrical corrosion of the bearing
When a motor is driven by the inverter, axial voltage is generated on the motor shaft, which may cause electrical
corrosion of the bearing in rare cases depending on the wiring, load, operating conditions of the motor or specific
inverter settings (high carrier frequency and EMC filter ON).
Contact your sales representative to take appropriate countermeasures for the motor.
The following shows examples of countermeasures for the inverter:
– Decrease the carrier frequency.
– Turn OFF the EMC filter.
– Provide a common mode choke on the output side of the inverter.
OFF connector setting.)
*1
Recommended common mode choke: FT-3KM F series FINEMET
Hitachi Metals, Ltd. FINEMET is a registered trademark of Hitachi Metals, Ltd.
Do not install a power factor correction capacitor, varistor or arrester on the inverter output side.
This will cause the inverter to trip or the capacitor, varistor, or arrester to be damaged. If any of the above devices is
installed, immediately remove it.
Before starting wiring or other work after the inverter is operated, wait for at least 10 minutes after the power supply has
been switched off, and check that there are no residual voltage using a tester or the like. The capacitor is charged with
high voltage for some time after power off and it is dangerous.
If "EV" is displayed on the operation panel, turn OFF the 24V external power supply before performing wiring.
A short circuit or earth fault on the inverter output side may damage the inverter modules.
– Fully check the insulation resistance of the circuit prior to inverter operation since repeated short circuits caused by
peripheral circuit inadequacy or an earth fault caused by wiring inadequacy or reduced motor insulation resistance
may damage the inverter modules.
– Fully check the to-earth insulation and inter-phase insulation of the inverter output side before power-on.
Especially for an old motor or use in hostile atmosphere, securely check the motor insulation resistance etc.
Do not use the inverter input side magnetic contactor (MC) to start/stop the inverter.
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.
Always use the start signal (ON/OFF of STF and STR signals) to start/stop the inverter.
Do not apply a voltage higher than the permissible voltage to the inverter I/O signal circuits.
Contact to the inverter I/O signal circuits or opposite polarity may damage the I/O devices. Especially check the wiring to
prevent the speed setting potentiometer from being connected incorrectly to short terminals 10E and 5.
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(This is effective regardless of the EMC filter ON/
®
common mode choke cores manufactured by
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