Help in Power Supply of PLC

Good day,

I know my question is a basic when using a PLC.
Can someone please tell me how do i select the right power supply for my PLC
how do i know if i will use, for example, 1769-PA2 or 1769-PA4. I am using a 1769-L35CR power supply with 1 1769-OB32 and 2 1769-IQ32 and 1 1769-IF10 thanks for your help in advance.

There are rules for Compact Logic power supplies. (Read the manual).
The one rule people forget is the 50/50 rule. A 1769-PA2 supplies 2.0 amps, but only 1.0 amp to the LEFT, and 1.0 amp to the RIGHT; a 50/50 split.
So, you might have to move your modules around, to match the load to the power supply.
Again, the manual shows all the detail on how to do this.

ah ok thx

jdbrandt said:

There are rules for Compact Logic power supplies. (Read the manual).
The one rule people forget is the 50/50 rule. A 1769-PA2 supplies 2.0 amps, but only 1.0 amp to the LEFT, and 1.0 amp to the RIGHT; a 50/50 split.

Click to expand...

Please explain this statement, cause I don't see the reason, specially for small power supplies. Power supplies we are talking about are voltage generators, so there is constant voltage, not constant current. Components inside unit should be far from one amp if producer is serious one. If it is stated 2.0A but with 50/50 split, it should be written.

I don't say that your are not wright, but that I don't see the reason.

Also to say, that it is very good practice to leave at least 20% reserve.

Goghie,

The 1769 power supply literature does a good job explaining the power supply limits, and the 1769 selection guide includes the current draw and distance rating of the IO modules and Processor. You can find these manuals at www.ab.com/literature.

However, it's often the case the folks will just buy the larger supply versus running the calculations.

The way I size 1769 power supplies is using the free IAB tool from AB.com. It's a big download but I use this software almost every day to build PLC boms.

Hope this helps,

Shawn

thanks for all the replies