Chapter Three - Installation
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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-
tions that can result in hazardous machine operation in certain applications. Noise may
be present at certain times, may appear between 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. These codes
provide data such as the size and types of conductors, color codes and connections nec-
essary for safe grounding of electrical components. It is recommended that the high volt-
age and low voltage cabling be separated and dressed apart. In particular, the AC cables
and switch wiring should not be in the same conduit with all communication cables.
Line Voltage Variation
The unit’s power supply is built to operate with output voltage ranges of 100-120 VAC
and 200-240 VAC with an AC power supply and 19-30 VDC with a DC power supply,
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.
In cases in which 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 volt-
age transformer.
The constant voltage transformer stabilizes the input voltage to the unit by compensating
for voltage changes at the primary in order to maintain a steady voltage at the secondary.
When using a constant voltage transformer, check that the power rating is sufficient to
supply the system.
Creating a Power Cable
This section describes how to create both an AC and a DC power cable.
AC Power Cable
A power cable must be created to supply power to the unit. The materials needed are:
•
A three-position power connector (supplied)
•
A braid/foil shielded power cable, terminated at power source end, with three 18 (1.0
mm), 16 (1.3 mm), or 14 (1.6 mm) Awg solid or stranded copper wires, rated 80ºC or
better