volt meter and signal

[rc_rs_ss]

Is there a programmable volt meter display that can measure up to 400 volts dc and send out a signal or alarm when a certain voltage is reached? I need to monitor the voltage of my batteries and then trip a relay when the voltage reaches 240 volts. Any help would be great. Thanks!

 

[daddles]

What you're describing is often the job of a comparator. If I was faced with the task you describe, that's the first thing that would come to mind. I'd look at using an LM339, as I have a bunch of them. The comparator's output would then need to drive e.g. a transistor that could then be used to switch the relay (or it might be able to drive a solid state relay).

 

[rc_rs_ss]

Yes it will be used to trip a solid state relay, This one-
http://www.alliedelec.com/search/productdetail.aspx?SKU=6820020
How would you go about doing this with the 240 volt target with the LM339? Are there any schematics or parts lists out there for this type of project? Thank you for the reply! Any more help would be great.