RBergmann
Member
Knowing full well that this is not an electrical forum but for PLCs, I have a question that applies to both.
We have a series of equipment that generally is field wired by the customer's electrician. One 24VDC PLC input, via terminal blocks, is for a "dry contact" (with our system providing the voltage source) signal to initiate and maintain a sequence.
For some reason, we are getting 240VAC applied (presumably by mistake) and it's taking out most, if not all, of our DC devices. This gets expensive as these can include power supplies, PLCs, HMIs as well as various other equipment.
By the time we are made aware of DC device failure, it's too late. Our equipment is located in various locations of the U.S.
Is there a circuit or device that can provide us a kind of front line defense against these mistakes? An MOV (wired in parallel) + fuse (wired in series with one leg of the dry contact circuit) was offered as a possible solution.
We have a series of equipment that generally is field wired by the customer's electrician. One 24VDC PLC input, via terminal blocks, is for a "dry contact" (with our system providing the voltage source) signal to initiate and maintain a sequence.
For some reason, we are getting 240VAC applied (presumably by mistake) and it's taking out most, if not all, of our DC devices. This gets expensive as these can include power supplies, PLCs, HMIs as well as various other equipment.
By the time we are made aware of DC device failure, it's too late. Our equipment is located in various locations of the U.S.
Is there a circuit or device that can provide us a kind of front line defense against these mistakes? An MOV (wired in parallel) + fuse (wired in series with one leg of the dry contact circuit) was offered as a possible solution.