GE 90-30 PLC Series Installation And Hardware Manual page 388

Calculating Series 90-30 Heat Dissipation
Appendix
F
Overview
Series 90-30 PLCs must be mounted in a protective enclosure. The enclosure should be capable of
properly dissipating the heat produced by all of the devices mounted inside it. This appendix
describes how to calculate heat dissipation for a Series 90-30 PLC. The strategy is to calculate a
heat dissipation value, in watts, for each individual module in the PLC. To obtain a total heat
dissipation figure for the PLC, add the individual values together.
The procedure consists of the following steps:
Information Required
GFK-0356Q
Step 1: Basic Method to Calculate Module Dissipation
Step 2: Calculation for PLC Power Supplies
Step 3: Output Calculations for Discrete Output Modules
Step 4: Input Calculations for Discrete Input Modules
Step 5: Final Calculation
In addition to the information in this manual, you will need GFK-0898, Series 90-30 I/O
Module Specifications Manual.
You will need operating current values for the discrete output devices connected to the PLC's
discrete output modules. These include control relays, motor starters, solenoids, pilot lights,
etc. Each device manufacturer publishes these values. If an exact value is not available for a
device, you can make a close estimate by obtaining the value for a similar device from a
catalog. These values are also needed for selecting Output modules during the design process
in order to ensure that the modules' maximum ratings are not exceeded.
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F-1