24 volt power monitor


Thread Starter

S Witte

Looking for a device to monitor a 24 volt power supply. We had a supply sag to 18 volts and it would not fire a solenoid causing intermediate quality problems in our process. Thought of using an analog card with resistors to get down to the 0 to 10 volt range or using a pot to drop down the holding voltage on a relay. But not sure how fail safe these would be. Any Ideas???

Curt Wuollet

There are quite a few chips that do that specifically and it's trivial to do with a comparator or even a 555. In a pinch, a Zener diode, resistor and a transistor will do. Some of the power supply vendors provide a power OK signal and some used to sell external monitors and crowbars as packaged functions. If you can't find a packaged function, email me and I can send you a drawing. With three parts, it wouldn't be hard to put on a terminal strip.


Try a Weidmuller Ultra Slimpak G108. It has a dipswitch settable input range with a relay output. Two alarm settings, hi or lo, failsafe or non-failsafe. Only requires 9 - 30VDC supply voltage. Even UL recognized.
SquareD sells din rail mount devices that have ajdustable voltage monitoring with relay output. A model can be selected for just about any ac or dc voltage from mv to 600v ranges.