Thread Starter


Joined Apr 25, 2005
I need to supply 240VAC to a set of lights in the field. I also need to control the lights within a control room by the use of a PLC. Is it possible to feed a 240V supply to a box containing some contactors and a couple of relays. The contactors having the 240V supply and subsequently feeding the lights. Can a PLC 24VDC supply be used to energise the controlling relays within that panel?. would this cause any problems?



Joined Apr 26, 2005
Switched 240 VAC is done with relays all the time.

You can see examples of it in HVAC equipments.

It's been done for over 50 years ago in high power [165 kW - 2.0 MW] transmitters. Of course since there were no PLC's, you had to manually operate the switches.

You will need an interface between the PLC and the relay.


Joined Jan 10, 2006
Over here 240 volts is the standard single phase supply. We use 240 volt PLC's all the time, no external relays, or separate 24v supply required (assuming a resitive load less than 10A).


Joined Jan 11, 2006
it is possible to use 240VAC PLC - like ZELIO LOGIC /see in google/. The module have rellay outputs and you can close the circuit of lamp direct with the rellay. If you have a 24VDC PLC you need from 240VAC/24VDC power supply to charge the relays. if you want a diagrams write to me -