Fuji Electric FRENIC-HVAC User Manual page 735

Target
No.
device
7 Pressure A pressure sensor
sensor malfunctioned.
<Possible cause>
The pressure sensor may
malfunction due to noise that
came from the box body
through the shielded wire.
Position
8
Erroneous-pulse outputs from
detector
a pulse converter caused a
(pulse
shift in the stop position of a
encoder)
crane.
<Possible cause>
Erroneous pulses may be
outputted by induction noise
since the power line of the
motor and the signal line of
the PG are bundled together.
Program
9 The PLC program sometimes
mable
malfunctions.
logic
controller
(PLC)
<Possible cause>
Since the power supply
system is the same for the
PLC and inverter, it is
considered that noise enters
the PLC through the power
supply.
Table A.2 Continued
Phenomena Noise prevention measures
1) Install an LC filter on
2) Connect the shield of
1) Install an LC filter and a
2) Install an LC filter at the
1) Install a capacitive filter
2) Install an LC filter on the
3) Lower the carrier
A-12
the input side of the
inverter.
the shielded wire of the
pressure sensor to the 0
V line (common) of the
pressure sensor,
changing the original
connection.
capacitive filter at the
input side of the inverter.
output side of the inverter.
and an LC filter on the
input side of the inverter.
output side of the inverter.
frequency of the inverter.
Notes
1) The shielded parts
of shield wires for
sensor signals are
connected to a
common point in
the system.
2) Conduction noise
from the inverter
can be reduced.
1) This is an
example of a
measure where
the power line and
signal line cannot
be separated.
2) Induction noise
and radiation
noise at the
output side of the
inverter can be
reduced.
1) Total conduction
noise and
induction noise in
the electric line
can be reduced.