Spectrum Controls SLC 500 User Manual page 20

2-6 Chapter 2: Installation and Wiring
WARNING
User's Manual Pub. 0300181-07 Rev. A
To wire the terminal block, you need:
A small, flat-blade screwdriver.
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Belden 8761 (shielded, twisted pair) cable or equivalent.
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Remove power before removing or inserting this module. When you
remove, or insert, a module with power applied, an electrical arc may
occur. An electrical arc can cause personal injury or property damage by:
Sending an erroneous signal to your system's field devices,
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causing unintended machine motion.
Causing an explosion in a hazardous environment.
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Electric arcing causes excessive wear to contacts on both the
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module and its mating connector and may lead to premature
failure.
Before wiring the terminal block, take some time to plan your system:
Power, input, and output (I/O) wiring must be in accordance with Class
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1, Division 2 wiring methods [Article 501-4(b) of the National Electrical
Code, NFPA 70] and in accordance with the authority having
jurisdiction.
Peripheral equipment must be suitable for the location in which it is
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used.
Ensure that the SLC 500 system is installed in a NEMA-rated enclosure
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and that the SLC 500 system is properly grounded.
• Route the 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. Generally, allow at least 6 in. (about 15.2 cm) of
separation for every 120 V of power.
• Routing the field wiring in a grounded conduit can reduce electrical
noise further.
• If the field wiring must cross AC or power cables, ensure that they cross
at right angles.
There is one shield pin for every two input channels. All shields are
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internally connected, so any shield terminal can be used with any
channel.
Ground the shield drain wire at only one end of the cable. The preferred
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location is at the shield connections on the terminal block. (Refer to
IEEE Std. 518, Section 6.4.2.7 or contact your sensor manufacturer for
additional details.)
• Keep all unshielded wires as short as possible.
To limit overall cable impedance, keep input cables as short as possible.
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Tighten screw terminals with care. Excessive tightening can strip a
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screw.
• Follow system grounding and wiring guidelines found in your SLC 500
Installation and Operation Manual.