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24. TROUBLESHOOTING
24.4 Nolse
There are two types of noises-external mises which cause malfunctioning of the inverter and
those radiated from the inverter to cause malfunctioning of a peripheral device. ARhough the in-
verters are designed not
to
be
influenced by noises, the following general measures must be
taken siree the inverter is an electronic device which handles weak signals. In addition, since the
inverter chops the output by high carrier frequency, the inverter itsel is a source of noise genera-
tion. If peripheral equipment is affected by the noise generated by the inverter, noise suppressing
measures must also be
taken. The
noise suppressing measures differ depending on noise
propagation route.
General measures
OAvoid running the power cable (inpuffoutput lines) and the signal lines in parallel
or
bundling them.
0
Use shielded twisted-wire pair cable for the connecting line
to the encoder and the
control signal lines. The sheathing of the shielded cable must be connected to terminal
SO.
0
Grounding must be single-point grounding for the inverter and the motor.
External noise can cause malfunctioning of the inverter
If noise generating equipment (magnetic contactor, electromagnetic brake, a number
of
relays, etc.) is installed near the inverter, and if the inverter could malfunction
due to the
noise generated by such equipment, it is
necessary to take the measures indicated below.
.To
install a surge suppressor in the equipment which generates noises to suppress
.To
install a data line filter in the signal lines.
0
Ground the line connecting to the encoder and the shield
of
the control signal lines
Noise radiated from the inverter that causes malfunctioning of peripheral devices
Noise generated by an inverter are largely classified into the following types-noise radiated
from the wires connected to the inverter and the inverter main circuit (inpuffoutput), noise in-
duced electromagnetically or electrostatically in the signal lines which is run close
to the
power cables of the main circuit, and noise which is transmitted through the
power supply.
noises.
with the metallic cable clamp.
Noises
transmhlec t h r o u g h
the power lines
I...
.
.Route 7)
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