Safety 3. Installation
3.5 Noise Countermeasures
To minimize electrical noise conditions, the following items must be observed in the system's
To minimize electrical noise condition, be sure of followings for wiring.
- The earth wire of the power supply should be grounded. (Ground resistance: 100 Ω or
less) It is important to ground the frame of Controller not only for prevention from
electric shock, but also for reducing the influence of electric noise around the
Controller's power cable to the ground terminal of the factory power supply. For
details about the plug and AC power cable, refer to the Setup & Operation 3.3 Power
- Do not tap power from a power line that connects to any equipment which may cause
- When you tap power for the Controller and the single-phase AC motor from the same
power line, change the phase of one or the other. Ensure that they will not be the
- Use a twisted pair motor power line.
- Do not run AC power lines and DC power lines in
the same wiring duct, and separate them as far as
power line and the Controller power line as far as
possible from the sensor or valve I/O lines; and do
not bundle both sets of wiring with the same cable
tie. If more than one duct/cable must cross each
other, they should cross perpendicularly.
preferable example is shown in the right figure.
- Wire as short as possible to the I/O connector and EMERGENCY connector. Use a
shielded cable and clamp the shield to the attached connector interior. Make sure to
keep away from the peripheral noise source as far as possible.
- Make sure that the induction elements used to connect to the Controller's I/O (such as
relays and solenoid valves) are noise suppression parts. If an induction element
without protection against noise is used, make sure to connect a noise suppression part
such as a diode located at the induction element in parallel with it. In selecting noise
suppression parts, make sure that they can handle the voltage and current incurred by
the induction load.
- To start and change revolutions of the conveyer's (or the like's) AC motor (ex: an
induction motor or three-phase induction motor) regularly or abruptly, make sure to
install a spark suppressor between the wires. The spark suppressor is more effective
when placed closer to the motor.
- As they are easily influenced by noise, keep cable such as USB, Ethernet, RS-232C, or
fieldbus away from peripheral noise sources.
Therefore, be sure to connect the earth wire (yellow/green) of the
For example, separate the AC motor
AC Line duct
As far as possible
DC line duct
RC700 / RC700-A Rev.23