output current from simatic PSU

hello,

just wondering whats the diffrence in the current out puts of the powersupplies, i have a s7 cpu-300 PLC with DI/O and AI/O moduals, is it better to get a PSU of 5A or 20A, whats better and why are there diffrent out puts, thanks

To answer your question, go to the module specification sheets (in the catalogue or on the net) and do a power budget for your projected configuration. Then choose a power supply that covers the requirements.
Hope this helps,
Daniel Chartier

How can I calculate the power requirements of my configuration?

Hello;
Power budget means summing Amps needed on the 24 V backplane + Amps needed on the L+ supply of the modules (if they are fed from the same power supply). Here are some extracts from data sheets for different S7-300 modules:

Simply look up the data for each module on your rack and add the different values. Keep a safety margin in case of short-circuit (I feel confortable with 50% spare power).
Hope this helps,
Daniel Chartier

hello,

im not quite sure how to do it, but i took a stab and i think i got about 10A would be ideal, can you check for me the power budget, this is what i have:

1 X Siemens S7 314IF PLC #6ES7 314-5AE02-0AB0

3 X Siemens Digital Input/Output DI16/DO16xDC24V #6ES7 323-1BL00-0AA0

1 X Siemens Analog Input AI 8x12bit #6ES7 331-7KF01-0AB0

1 X Siemens Digital Input DI16xDC24V #6ES7 321-1BH01-0AA0

thanls in advanced

to add on that, i have a 5A powersupply, is this suffeince for the above list. thanks

Hey, why not ask Siemens to do the arithmetic for you? If they're going to sell you (or have already sold you) a PSU, the least they could do is give you some indication of whether it will work or not. Give them a ring and see what they say.


Ken