Calculating Plc Heat Dissipation; System Layout Guidelines; Benefits Of A Good Layout - Safe, Reliable, And Accessible; Plc Rack Location And Clearance Requirement - GE 90-30 PLC Series Installation And Hardware Manual

Calculating PLC Heat Dissipation

The amount of heat dissipated by a PLC mounted in an enclosure can be an important factor in
determining the enclosure size needed for the system. This is because the enclosure must be able to
adequately dissipate the heat generated by all of the components mounted inside so that no
components overheat. PLC heat dissipation is also a factor in determining the need for enclosure
cooling options such as fans and air conditioning. Enclosure manufacturers generally consider
enclosure heat dissipation as a factor in their enclosure selection guidelines. Instructions for
calculating Series 90-30 PLC heat dissipation can be found in Appendix F, "Series 90-30 Heat
Dissipation."

System Layout Guidelines

Because of the differences from one system to another, it is not practical to try to discuss every
possible layout. Instead, this section offers guidelines and an example to help you lay out your
system.

Benefits of a Good Layout - Safe, Reliable, and Accessible

The layout of your system has a lot to do with how reliably your system will operate, how easy it is
to install, how well it looks, and how easy and safe it is to maintain:

PLC Rack Location and Clearance Requirement

The following list provides PLC rack mounting location guidelines. For an example layout, see the
figure "Series 90-30 Example Layout" later in this chapter.
GFK-0356Q Chapter 12 System Design
Safety and Maintenance - A good layout helps minimize the chance of electrical shock to
personnel working on the system. It lets maintenance technicians easily access the unit to
make measurements, load software, check indicator lights, remove and replace modules, etc. It
also makes it easier to trace wiring and locate components while troubleshooting.
Reliability -Proper layout promotes good heat dissipation and helps eliminate electrical noise
from the system. Excess heat and noise are two major causes of electronic component failure.
Installation Efficiency- A well designed layout allows sufficient room to mount and wire the
unit. This saves time and frustration.
Appearance - A neat and orderly layout gives others a favorable impression of your system.
It lets others know that careful thought went into the design of the system.
Locate PLC racks away from other components that generate a lot of heat, such as
transformers, power supplies, or power resistors.
Locate PLC racks away from components that generate electrical noise such as relays and
contacts.
Locate PLC racks away from high voltages components and wiring such as circuit breakers
and fusible disconnects, transformers, motor wiring, etc. This not only reduces electrical
noise, but makes it safer for personnel working on the PLC.
System Design and Layout
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