Appendix G Definition Of Key Terms; Calculating Module Heat Dissipation - Allen-Bradley SLC 500 User Manual

Definition of Key Terms
Calculating Module Heat
Dissipation
Allen-Bradley PLCs
1
Calculating Heat Dissipation for the SLC 500
Control System
This appendix will assist you in calculating the heat dissipation of
your SLC 500 controller. It consists of the following:
• definition of key terms
• table and graphs
• example heat dissipation calculation
• heat dissipation worksheet
To select an enclosure see page 2-18.
The following terms are used throughout this appendix. Familiarize
yourself with them before proceeding further.
Watts per Point — maximum heat dissipation that can occur in each
field wiring point when energized.
Minimum Watts — amount of heat dissipation that can occur when
there is no field power present.
Total Watts — the watts per point plus the minimum watts (with all
points energized).
To calculate the heat dissipation of your SLC controller you must
consider two things:
• the maximum heat dissipated (with field power applied) by the
processor, all I/O and specialty modules, and any peripheral
devices for each chassis.
• the heat dissipated by the power supply. This is determined by
the maximum load on the power supply of the processor, each
I/O and specialty module, peripheral device, and device
drawing power directly off the power supply via the "POWER
OUT" terminals.
Appendix
Publication 1747-UM011C-EN-P - December 2001
G