Rockwell Automation 1785-LTx,D17856.2.1 Classic PLC-5 Programmable Controllers Users Manual - Manual (Page 173)

Design Worksheets
Appendix B
B-23
Select Power Supplies
For more information on: See:
Selecting power supplies Classic 1785 PLCĆ5 Programmable Controllers User Manual, publication 1785Ć6.2.1, Chapter 2:
Selecting Power Supplies
Selecting power supply cables Automation Products Catalog, publication AP 100
1. Make a copy of this worksheet for each of your chassis.
2. Refer to the following worksheets for the values that you need to complete the formula to select a
power supply.
Assign I/O Modules to Chassis and Assign Addresses worksheet for total I/O current draw
Select Adapter Module or Select Classic PLC-5 Processor worksheet for current draw
3. Perform the following steps to calculate the total current required for chassis number
____________ and to select a power supply.
On line A below, record the total backplane current draw for all I/O modules in the chassis. If
you leave slots available in your chassis for future expansion, add current draw for future I/O
modules.
On line B below, record the current draw required for the classic PLC-5 processor or the adapter
module in the chassis.
On line C below, record the total current required from a power supply for that chassis.
A—Total I/O backplane current ____________________
B—PLC-5 processor/adapter module current + ____________________
C—Total backplane current required = ____________________
4. Choose your power supply dependent on the input voltage requirement and the total backplane
current required (line C above). Two types of power supplies are:
power supply modules—located in the same chassis as the PLC-5 processor or adapter module
power supplies—located external to the chassis containing the PLC-5 processor or adapter
module
5. Record your power supply and cable choice below.
Power supply for this chassis is: _____________________________________
Cable for this power supply is: _____________________________________
Important: You cannot use an external power supply and a power supply module to power the
same chassis; they are not compatible.