Fuji Electric frenic mini series - Page 266

App. A Advantageous Use of Inverters (Notes on electrical noise)
A-5
App.
[ 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.
Table A.1 Noise Prevention Measures
Goal of noise prevention
measures
Conduction route
Noise prevention method
Make it
more
difficult
to
receive
noise
Cutoff
noise
conduc-
tion
Confine
noise
Reduce
noise
level
Conduc-
tion
noise
Induc-
tion
noise
Radia-
tion
noise
Separate main circuit
from control circuit

Y Y
Minimize wiring
distance

Y Y Y Y
Avoid parallel and
bundled wiring

Y Y
Use appropriate
grounding

Y Y Y Y
Use shielded wire and
twisted shielded wire

Y Y Y
Use shielded cable in
main circuit

Y Y Y
Wiring and
installation
Use metal conduit pipe
Y Y Y
Appropriate arrangemen
t
of devices in panel
Y Y Y
Control
panel
Metal control panel
Y Y Y
Line filter
Y Y Y Y
Anti-noise
device
Insulation transformer
Y Y Y
Use a passive capacitor
for control circuit

Y Y Y
Use ferrite core for
control circuit

Y Y Y Y
Measures at
noise
receiving
sides
Line filter
Y Y Y
Separate power supply
systems

Y Y
Others
Lower the carrier
frequency

Y* Y Y Y
Y: Effective, Y*: Effective conditionally, Blank: Not effective