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WATLOW Series 942 User's Manual
Appendix
Install - Wire
Appendix 2
Noise and Installation Guidelines
Installation Guidelines For Preventing Noise
For improved electrical noise immunity, install the Series 942 as far away as
possible from motors, relays, and other similar electrical noise generators.
Do not run low power (sensor input) lines in the same bundle as AC power
lines. Grouping these lines in the same bundle can create electrical noise
interference which may result in error codes in the Series 942.
The Culprit
Most noise problems stem from wiring practices. They're the major means of
coupling noise from its sources to the control circuit. The following information
will tell you how to eliminate or decrease noise.
An Information Resource
For wiring guidelines , refer to the IEEE Standard No. 518-1982, available from
IEEE, Inc. 345 East 47th Street, New York, NY 10017.
Noise Sources
• Switches and relay contacts operating inductive loads such as motors, coils,
solenoids, and relays, etc.
• Thyristors or other semiconductor devices which are not zero crossover-
fired (randomly-fired or phase angle-fired devices).
• All welding machinery.
• Heavy current carrying conductors.
• Fluorescent and neon lights.
How To Decrease Noise Sensitivity
• Physical separation and wire routing must be given careful consideration in
planning the layout of the system. For example, A.C. power supply lines
should be bundled together and physically kept separate from input signal
lines (sensor lines). A 12" (305 mm) minimum separation is usually effec-
tive. Keep all switched output signal lines (high power level) separate from
input signal lines (sensor lines). Cross other wiring at 90
°
angles whenever
crossing lines is unavoidable.
