11
PRECAUTIONS FOR USE OF THE
INVERTER
4 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 size to make a voltage drop 2% maximum.
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
for the recommended cable sizes.
(5) The overall wiring length should be 500m (1640.4 feet) maximum.
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
(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.
(7) Do not install a power factor correction capacitor, surge suppressor or radio noise filter 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.
(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/+-N/- of the inverter is not more than 30VDC using a tester, etc.
(9) A short circuit or 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 a ground fault caused by wiring inadequacy or reduced motor insulation resistance
may damage the inverter modules.
· Fully check the to-ground insulation and phase to 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.
(10) Do not use the inverter input side magnetic contactor to start/stop the inverter.
Always use the start signal (ON/OFF of STF and STR signals) to start/stop the inverter.
(11) Do not apply a voltage higher than the permissible voltage to the inverter I/O signal circuits.
Application of permissible voltage to the inverter I/O signal circuit and incorrect polarity may damage the I/O terminal.
Especially check the wiring to prevent the speed setting potentiometer from being connected incorrectly to short
terminals 10E-5.
(12) Provide electrical and mechanical interlocks for MC1 and MC2
which are used for bypass operation.
When the wiring is incorrect and if there is a bypass operation
circuit as shown right, the inverter will be damaged when the
power supply is connected to the inverter U, V, W terminals, due
to arcs generated at the time of switch-over or chattering caused
by a sequence error.
(13) If the machine must not be restarted when power is restored
after a power failure, provide a magnetic contactor in the inverter's input side and also make up a sequence which will
not switch on the start signal.
If the start signal (start switch) remains on after a power failure, the inverter will automatically restart as soon as the
power is restored.
(14) Instructions for overload operation
When performing operation of frequent start/stop of the inverter, increase/decrease in the temperature of the transistor
element of the inverter may repeat due to a continuous flow of large current, shortening the life from thermal fatigue.
Since thermal fatigue is related to the amount of current, the life can be increased by reducing bound current, starting
current, etc. Decreasing current may increase the life. However, decreasing current will result in insufficient torque and
the inverter may not start. Therefore, increase the inverter capacity to have enough allowance for current.
(15) Make sure that the specifications and rating match the system requirements.
(16) If electromagnetic noise generated from the inverter causes frequency setting signal to fluctuate and motor rotation
speed to be unstable when changing motor speed with analog signal, the following countermeasures are effective.
· Do not run the signal cables and power cables (inverter I/O cables) in parallel with each other and do not bundle them.
· Run signal cables as far away as possible from power cables (inverter I/O cables).
· Use shield cables as signal cables.
· Install a ferrite core on the signal cable (Example: ZCAT3035-1330 TDK).
Power
supply
Inverter
Undesirable current
MC2
MC1
Interlock
U
V
W
R/L1
S/L2
T/L3
IM
