I need to build an alarm panel to monitor a number of 4-20 madc signals for out of range,high and low.

Adjustable current sensing relays are too large and too expensive for this project.

I need another approach, using something that will operate smaller and cheaper relays that will trigger the alarms.

Any help would be greatly appreciated.

Thank you in advance.

bob mcm

 

Can the current signals be converted to voltages refferencerd to ground, or to some voltage ref.? If only inline monitoring possible try an analog optical isolator,comparators,latches & lights or audible alarms as required.

 

If this panel goes in any public space, you will probably need to get it approved for insurance and local firefighting. You might even have to post a surety bond as to performance.