Maintenabce
and
Tr
oubleshooting
Maintenance
and
Tr
oubleshooting
8--10
Maintenance and Troubleshooting
DL105 PLC User Manual, 3rd Edition
Noise Troubleshooting
Noise is one of the most difficult problems to diagnose. Electrical noise can enter a
system in many different ways and they fall into one of two categories, conducted or
radiated. It may be difficult to determine how the noise is entering the system but the
corrective actions for either of the types of noise problems are similar.
S
Conducted noise is when the electrical interference is introduced into
the system by way of a attached wire, panel connection ,etc. It may
enter through an I/O circuit, a power supply connection, the
communication ground connection, or the chassis ground connection.
S
Radiated noise is when the electrical interference is introduced into the
system without a direct electrical connection, much in the same manner
as radio waves.
While electrical noise cannot be eliminated it can be reduced to a level that will not
affect the system.
S
Most noise problems result from improper grounding of the system. A
good earth ground can be the single most effective way to correct noise
problems. If a ground is not available, install a ground rod as close to
the system as possible. Ensure all ground wires are single point
grounds and are not daisy chained from one device to another. Ground
metal enclosures around the system. A loose wire can act as a large
antenna, introducing noise into the system. Therefore, tighten all
connections in your system. Loose ground wires are more susceptible to
noise than the other wires in your system. Review Chapter 2 Installation,
Wiring, and Specifications if you have questions regarding how to
ground your system.
S
Electrical noise can enter the system through the power source for the
PLC and I/O circuits. Installing an isolation transformer for all AC
sources can correct this problem. DC sources should be well-grounded
good quality supplies.
S
Separate input wiring from output wiring. Never run low-voltage I/O
wiring close to high voltage wiring.
Electrical Noise
Problems
Reducing
Electrical Noise
Содержание DL105
Страница 2: ...DL105 PLC User Manual Manual Number D1 USER M...
Страница 308: ...1B DL105 Error Codes In This Appendix Error Code Table...
Страница 314: ...1C Instruction Execution Times In This Appendix Introduction Instruction Execution Times...
Страница 324: ...1D Special Relays In This Appendix DL105 PLC Special Relays...
Страница 327: ...1E PLC Memory In This Appendix DL105 PLC Memory...
Страница 329: ...1F European Union Directives CE In This Appendix European Union EU Directives Basic EMC Installation Guidelines...