Appendix A Trouble-free Use of Inverters (Notes on electrical noise)
Appendix-11
Table A-2 Examples of Noise Prevention Measures (Continued)
No.
Target
device
Phenomena Measure
Notes
8 Position
detector
(pulse
encoder)
Erroneous-pulse outputs from a
pulse converter caused a shift
in the stop position of a crane.
<Possible cause>
The motor power line and the
signel line for the encoder are
wired together in a bundle. This
produces induction noise to
cause output of error pulses.
1) Install an LC filter and a
capacitive filter at the input
side of the inverter.
2) Install an LC filter at the
output side of the inverter.
1) This is an example
of a measure
where the power
line and signal line
cannot be
separated.
2) Induction noise
and radiated noise
at the output side
of the inverter can
be reduced.
9 Program
mable
logic
controller
(PLC)
The PLC program sometimes
malfunctions.
<Possible cause>
Power sources of the inverter
and PLC are in the same
system so that noise enters
PLC via the power source.
1) Install a capacitive filter and
an LC filter on the input side
of the inverter.
2) Install an LC filter on the
output side of the inverter.
3) Lower the carrier frequency
of the inverter.
1) Total conducted
noise and
induction noise in
the electric line can
be reduced.
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