Spectrum Controls 140 EHC 204 00sc User Manual
Page 15
Quantum Series 140 EHC 204 00sc 140 EHC 208 00sc
16
Reducing Noise
Most applications require installation in an industrial enclosure to reduce the effects of electrical interference.
Electrical noise, to which analog inputs and outputs are highly susceptible, will reduce the performance (accuracy)
of the module.
Selecting a Location
WARNING EXPLOSION HAZARD This equipment is suitable for use in Class I, Division
2, Groups A, B, C, D or nonhazardous locations only. Substitution of components may impair suitability for
Class I, Division 2. Do not replace, connect, or disconnect components unless power has been switched off
or the area is known to be nonhazardous. This product must be installed in an enclosure. All wiring must
comply with N.E.C. article 501-4(b).
Two factors determine where to install the module in the PLC rack: ambient temperature and electrical noise.
Place the module:
•
In any slot but slot 0 (reserved for the processor).
•
Close to the bottom of the enclosure to take advantage of cooler air.
•
Away from modules that generate significant heat, such as 32-point I/ O modules.
•
In a slot away from AC or high-voltage DC modules, hard contact switches, relays, and AC motor
drives.
•
Away from the rack power supply (if installing a modular controller system).
Protecting Circuit Boards from Contamination
The printed circuit boards of the module must be protected from dirt, oil, moisture, and other airborne
contaminants. Ensure that the module is kept in an enclosure at all times. The interior of the enclosure should
be kept clean and the enclosure door should be kept closed whenever possible.
Wiring
•
For UL and CUL compliance, power and input/output wiring must be in accordance with Class 1,
Division 2 wiring methods (Article 501-4(b) of the National Electrical Code, NFPA 70) and in
accordance with the authority having jurisdiction.
•
Channels are isolated from one another.
•
Route field wiring away from any other wiring and as far as possible from sources of electrical noise,
such as motors, transformers, contactors, and ac devices. As a general rule, allow at least 15.2 cm (6
in.) of separation for every 120V of power.