Fuji Electric FRENIC-HVAC User Manual page 734

Target
No. Phenomena
device
5 Photo- A photoelectric relay
electric malfunctioned when the
relay inverter was operated.
<Possible cause>
Although the inverter and
photoelectric relay are
separated by a sufficient
distance but the power
supplies share a common
connection, it is considered
that conduction noise entered
through the power supply line
into the photoelectric relay.
6 Prox- A proximity switch
imity malfunctioned.
switch
(capaci-
tance
type)
<Possible cause>
It is considered that the
capacitance type proximity
switch is susceptible to
conduction and radiation
noise because of its low
noise immunity.
App. A Advantageous Use of Inverters (Notes on electrical noise)
Table A.2 Continued
Noise prevention measures
1) Insert a 0.1 µF capacitor
between the output
common terminal of the
amplifier of the
photoelectric relay and
the frame.
1) Install an LC filter at the
output side of the inverter.
2) Install a capacitive filter
at the input side of the
inverter.
3) Ground the 0 V
(common) line of the DC
power supply of the
proximity switch through
a capacitor to the box
body of the machine.
A-11
Notes
1) If a low-current
circuit at the
malfunctioning
side is observed,
the measures
may be simple
and economical.
1) Noise generated
in the inverter
can be reduced.
2) The switch is
superseded by a
proximity switch
of superior noise
immunity (such
as a magnetic
type).