1. System Installation Requirements
1-22
TI 33J01J10-01EN
1.5 Noise Countermeasures
Noise may be induced by electromagnetic induction, electrostatic induction, or from radio
waves,lightning,inductiveloads,staticelectricityandgroundpotentialdierences.Itcan
be picked up by power, signal and ground cables, and devices. With computerized control
systems, noise-induced errors in A/D conversion or in an instruction word may lead to
malfunction.
To prevent noise and electrostatic buildup, take the measures described in this section in
deciding cable type, cable routing, and grounding.
1.5.1 Noise Sources and Noise Countermeasures
It is not easy to identify the cause of any noise-triggered errors or failures due to their lack
of reproducibility.
If noise problems occur, take the following countermeasures.
countermeasures:
Table Noise Sources & Countermeasures
Noise sources Eects Countermeasures
Electromagnetic induction
(magneticeld)
• Destroys magnetic disk data.
• Shield power cables with metallic conduits.
substance (e.g. Permalloy).
• Use twisted-pair cables.
Electrostatic induction
• Equipment maloperation.
• Interference with signals.
• Use shielded signal cables.
• Electrically separate power and signal cables
using metallic conduits and separators.
• Lay power and signal cables which intersect at
right angles.
Lightning
• Interference with signals.
• Equipment maloperation.
• Component damage.
• Lay cables underground.
• Lay cables as close to ground as possible if the
cables cannot be laid underground.
Electrostatic discharge
• Equipment maloperation.
• Electronic component deterioration,
damage.
• Paper jam.
• Discharge static electricity from operators.
• Ground equipment properly.
Inductive load open/close
• Spike noise interference to power
andsignal lines.
• Add spark-killer to noise source.
• Separate laying of cables.
Radio(electriceld)
• Equipment maloperation.
• Interference with signals.
away from the system so as not to exceed the
Groundpotentialdierence
• Equipment Maloperation
(noise imposed on signal lines)
Dec. 28, 2015-00
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