Precautions For Use Of The Inverter - Mitsubishi F700 Series Instruction Manual

3.5 Precautions for use of the inverter

The FR-F700 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.
(1) Use crimping terminals with insulation sleeve to wire the power supply and motor.
(2) Application of power to the output terminals (U, V, W) of the inverter will damage the inverter. Never perform
such wiring.
(3) 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 an enclosure etc., take care not to allow chips and other foreign matter to enter the inverter.
(4) Use cables of the appropriate size to make a voltage drop to 2% or less.
If the wiring distance is long between the inverter and motor, a main circuit cable voltage drop will cause the motor
torque to decrease especially at the output of a low frequency.
Refer to page 17 for the recommended cable sizes.
(5) The overall wiring length should be within the prescribed length.
Especially for long distance wiring, the fast-response current limit function may decrease or the equipment
connected to the secondary 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 19.)
(6) 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, set the EMC filter valid to
minimize interference. (Refer to page 13)
(7) Do not install a power factor correction capacitor, surge suppressor or capacitor type filter on the inverter
output side.
This will cause the inverter to trip or the capacitor and surge suppressor to be damaged. If any of the above
devices are installed, immediately remove it.
(8) For some short time after the power is switched OFF, a high voltage remains in the smoothing capacitor.
When accessing the inverter for inspection, wait for at least 10 minutes after the power supply has been switched
OFF, and then make sure that the voltage across the main circuit terminals P/+ and N/- of the inverter is no more
than 30VDC using a tester, etc.
(9) A short circuit or earth (ground) 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 (ground) fault caused by wiring inadequacy or reduced motor insulation
resistance may damage the inverter modules.
· Fully check the to-earth (ground) insulation and phase to phase insulation of the inverter output side before power-ON.
Especially for an old motor or use in a hostile atmosphere, securely check the motor insulation resistance etc.
(10) Do not use the inverter input side magnetic contactor 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. (Refer to page 12)
(11) Do not apply a voltage higher than the permissible voltage to the inverter I/O signal circuits.
Application of a voltage higher than the permissible voltage 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.

Precautions for use of the inverter

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