APPX
Appendix 6 EMC and Low Voltage Directives
175
A
■ Noise filter (power supply line filter)
A noise filter is effective for reducing conducted noise in the 10MHz or less frequency band. (Use of a noise filter can
suppress noise.)
The following are the installation precautions.
• Do not bundle the cables on the input side and output side of the noise filter. If bundled, the noise on the output side is
induced into the filtered cable on the input side.
• Ground the ground terminal of the noise filter to the ground point of the control panel with the shortest cable possible
(approximately 10cm).
■ Isolation transformer
An Isolation transformer is effective for reducing conducted noise (especially, lightning surge). Lightning surge may cause
malfunction of the programmable controller. As measures against lightning surge, connect an isolation transformer as shown
below. Use of an isolation transformer can reduce a lightning effect.
• Problematic example
Noise is induced when the input and output cables are bundled.
• Modification example
Install the input and output cables separately.
Filter
Induction
Input side
(power supply side)
Output side
(device side)
Filter
Input side
(power supply side)
Output side
(device side)
100VAC
200VAC
T1
Programmable
controller power
supply
Isolation
transformer
Programmable
controller
Motor power supply
Motor
equipment
Main
power supply
I/O power supply
I/O equipment
Relay
terminal
block
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