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Installation Considerations
Our products have been designed and tested for operation in the most demanding industrial environments.
Modern solid-state industrial controls are complex electronic equipment that operate at low levels of voltage and
current, co-existing with components that operate at much higher levels of power. The difference in operating
power characteristics between the high and low power control devices creates the possibility of unwanted signals
being generated, thus causing interference. The interference, which is a by-product of electrical noise, is not
present at all times. However, if it appears at random and for brief periods of time, it can cause disruptions and
errors in the operation of a control system.
Enhancement of a system’s noise level immunity and its tolerance to other enviro nmental hazards can be
accomplished by following proper system installation guidelines. The recommendations are of a general nature
and constitute good industrial installation practice.
General Environmental Considerations
Avoid installing EZ3 Series TouchPLC in areas where the following conditions may exist:
Environmental temperatures above or below those specified by the EZ3 Series TouchPLC
Prolonged exposure to humidity and liquids which may be sprayed or splashed on the equipment
Dusty environments where airborne particles may accumulate on equipment causing reduction of heat
dissipation and reduction in effective electrical spacing between components
Areas with excessive vibration
Areas with high-radiated electrical noise, such as near fields of transmitting antennas and areas in close
proximity of arc welding stations
Physical Layout in a Control Cabinet
When possible, cabinets housing electronic equipment should be designed with provisions for natural or forced
ventilation to facilitate heat dissipation. Observe the following rules for cabinet installation:
Heat generating equipment (power supplies and other heat inducing components) should be installed toward
the top of the cabinet. The lower space in the cabinet is cooler than the top area.
Install heat-sensitive components in the lower section.
Provide enough space between components to allow a free flow of air for better heat dissipation.
Provide the maximum possible physical separation between solid state and electromechanical controls. If
possible, the electromechanical controls (motors, starters, solenoids, etc.) should be housed separately or at
the farthest point when enclosed within the cabinet.
We recommend that the EZ3 Series TOUCHPLC have a minimum clear space of 2" on all sides for adequate
ventilation as shown in the image on the left.
Electrical Considerations
This section is designed to provide you with a very basic understanding of
electrical noise and how to keep it away from CPUs. Industrial plants have a
number of generators of electrical noise that are sometimes also referred to as
Radio Frequency Interference (RFI). Anytime an inductive load like a motor,
motor starter, or solenoid is turned off, it generates a burst of excess energy that
has to flow back to ground, just like electrical energy from a lightning storm has
to flow back to Earth. RFI is short bursts of electrical energy at very high
frequencies. Other sources include RF Welders or Radio Transmitters.
Effect of RFI on Electronic Automation Equipment
Electronic controls use faster and faster CPUs today. These CPUs are also operating at 2.5V to 5VDC logic level
power supply. RFI, if allowed to enter the CPU inside, is a killer of logic. A CPU under this environment loses its
brain and behaves erratically. A smart industrial-grade CPU like the EZ3 Series TOUCHPLC Card Engine, when faced
with RFI, halts its operation instead of giving false outputs.
Types of RFI
RFI enters electronic controls in two ways: radiated RFI or conducted RFI. For most practical purposes, electronic
devices, unless sitting right next to a powerful RFI transmitter, will not be affected by noise because air space
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