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Excessive Heat
The systems withstand temperatures from 0º to 50º C. They are cooled by convection, in
which a vertical column of air is drawn in an upward direction over the surface of its
components. To keep the temperature in range, the cooling air at the base of the system
must not exceed 50° C. Allocate proper spacing between internal components installed in
the enclosure.
When the air temperature is higher than the specified maximum in the enclosure, use a
fan or air conditioner to lower the temperature.
Electrical Noise
Electrical noise is seldom responsible for damaging components, unless extremely high
energy or high voltage levels are present. However, noise can cause temporary malfunc-
tioning which can result in hazardous machine operation in certain applications. Noise
may be present only at certain times, may appear at widely-spread intervals, or in some
cases may exist continuously.
Noise commonly enters through input, output, and power supply lines and may also be
coupled through the capacitance between these lines and the noise signal carrier lines. This
usually results from the presence of high voltage or long, close-spaced conductors. When
control lines are closely spaced with lines carrying large currents, the coupling of magnetic
fields can also occur. Use shielded cables to help minimize noise. Potential noise genera-
tors include switching components, relays, solenoids, motors, and motor starters.
Refer to the relevant Federal, State/Provincial, and local electric codes, which provide
data such as the size and types of conductors, color codes and connections necessary for
safe grounding of electrical components. It is recommended that high- and low-voltage
cabling be separated and dressed apart. In particular, AC cables and switch wiring should
not be in the same conduit with all communication cables.
Line Voltage Variation
The power supply section of the unit is built to sustain line fluctuations of 90-250 VAC
and still allow the system to function within its operating margin. As long as the incom-
ing voltage is adequate, the power supply provides all the logic voltages necessary to
support the processor, memory, and I/O.
When the installation is subject to unusual AC line variations, use a constant voltage
transformer to prevent the system from shutting down too often. However, a first step
toward the solution of the line variations is to correct any possible feed problem in the
distribution system. If this correction does not solve the problem, use a constant voltage
transformer.
The constant voltage transformer stabilizes the input voltage to the systems by compen-
sating for voltage changes at the primary in order to maintain a steady voltage at the sec-
ondary. When using a constant voltage transformer, check that the power rating is suffi-
cient to supply the unit.
