# How to determin the load requirement for 24V DC power supply

I'm working in automotive industry, I got a project to add extra hardware to particular line. hardware actually requires 24v 70w. Now, we have a Power supply unit "power one he-24V-7.2a" in the cabinet. For which "n" number of sensors, limit switches, grippers, power supply for I/o modules of plc, etc are connected. I Couldn't exactly find what are all the devices are connected for 24v Power-supply hardly sensors. But lot of sensors. I don't have any document to check the load requirement of this particular line. Only I can see is Output of the power supply is connected to 8A fuse.

By considering this I'm thinking the load requirement of this line might be =24V*8A =200W approx. is this 200W is load requirement of line?

If I add extra hardware(24v, 70w) to this powersupply. Do my power ratings and voltage ratings differs. Could some one explain me exactly how to deal.

thank you I'm new to this world ur help is appreciated

• 8A is an upper bound, certainly. It could be less than 8A but with that fuse it won't be more than 8A. – user253751 Apr 28 '18 at 2:35
• So my total current would be less than 8A for all the sensor and switches whatever are connected to this power supply right? so does it make any difference if I connect a hardware which takes 3A. – Jose Apr 28 '18 at 3:29
• As long as the total current is less than the power supply's rated current (which it looks like is probably 7.2A), you should be fine. The fuse won't blow until you hit 8A, but the power supply won't be happy at that current, and might not provide 24V. – Hearth Apr 28 '18 at 3:45
• Calculate (or measure) the current from the existing PSU to the existing load. 24V 70W means you need 3A additional, so if the PSU is currently supplying less than 4A of its 7.2A rating it should be able to drive the extra load (if it's properly cooled and fed from an adequate source etc etc) – Brian Drummond Apr 28 '18 at 10:40