Excessive Heat; Electrical Noise - Xycom 9462 System Manual

9460/9460KP/9462/9462KP System Manual
continuous, and able to safely conduct the ground-fault current in the system with mini-
mal impedance (minimum wire required is 18 Awg, 1 mm).
Observe the following practices:
•
Separate ground wires (P.E. or Protective Earth) from power wires at the point of
entry to the enclosure. To minimize the ground wire length within the enclosure, lo-
cate the ground reference point near the point of entry for the plant power supply.
•
All electrical racks or chassis and machine elements should be Earth Grounded in in-
stallations where high levels of electrical noise can be expected. The rack/chassis
should be grounded with a ground rod or attached to nearby Earth structure such as a
steel support beam. Each different apparatus should be connected to a single Earth
Ground point in a "star" configuration with low impedance cable. Scrape away paint
and other nonconductive material from the area where a chassis makes contact with
the enclosure. In addition to the ground connection made through the mounting bolt
or stud, use a one-inch metal braid or size #8 AWG wire to connect between each
chassis and the enclosure at the mounting bolt or stud.

Excessive Heat

The units withstand temperatures from 0º to 50ºC. The systems 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-
tions which can result in hazardous machine operation in certain applications. Noise may
be present only at certain times, may appear as 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 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 mag-
netic fields can also occur. Use shielded cables to help minimize noise. Potential noise
generators include switching components relays, solenoids, motors, and motor starters.
Refer to the relevant Federal, State/Provincial, and local electric codes which provides
data such as the size and types of conductors, color codes and connections necessary for
safe grounding of electrical components. It is recommended that the high voltage 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.
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