Fuji Electric FRENIC-HVAC User Manual page 729

[ 2 ] Implementation of noise prevention measures
There are two types of noise prevention measures--one for noise propagation routes and
the other for noise receiving sides (that are affected by noise).
The basic measures for lessening the effect of noise at the receiving side include:
Separating the main circuit wiring from the control circuit wiring, avoiding noise effect.
The basic measures for lessening the effect of noise at the generating side include:
1) Inserting a noise filter that reduces the noise level.
2) Applying a metal conduit pipe or metal control panel that will confine noise, and
3) Applying an insulated transformer for the power supply that cuts off the noise
propagation route.
Table A.1 lists the noise prevention measures, their goals, and propagation routes.
Noise prevention method
Separate main circuit
from control circuit
Minimize wiring distance
Avoid parallel and
bundled wiring
Wiring and Use appropriate
installation grounding
Use shielded wire and
twisted shielded wire
Use shielded cable in
main circuit
Use metal conduit pipe
Appropriate arrangement
Control
of devices in panel
panel
Metal control panel
Line filter
Anti-noise
device
Insulation transformer
Use a passive capacitor
for control circuit
Measures at
noise
Use ferrite core for
receiving
control circuit
sides
Line filter
Separate power supply
systems
Others
Lower the carrier
frequency
Y: Effective, Y*: Effective conditionally, Blank: Not effective
Table A.1 Noise Prevention Measures
Goal of noise prevention
measures
Make it
more Cutoff
difficult noise
to conduc-
receive tion
noise
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
A-6
Conduction route
Reduce Conduc-
Confine
noise tion
noise
level noise
Y
Y Y
Y
Y
Y
Y Y
Y
Y
Y Y
Y
Y* Y
Induc- Radia-
tion tion
noise noise
Y
Y Y
Y
Y
Y Y
Y Y
Y Y
Y Y
Y Y
Y
Y
Y Y
Y Y
Y Y