A_Large_Hand
Member
- Location
- Auburn, AL
Hello all, this is my first post!
I am a mechanical engineer with background in electronic packaging. I work in the water industry and there is a large need for water meters to send an electrical signal to an external device (usually PLC occasionally SCADA) to trigger an external valve, activate a pump, perform SOME type of mechanical action. This is usually required for some process--i.e. injecting chemicals into the stream (depending on the type and use of flow of course).
The issue I am having is--why would the owner/operator of the third party device specify a dry contact requirement? I see the value in the dry contact if there is no form of external power that can be applied to the device sending the electrical signal, but other than that I am struggling to see value.
Is there a safety issue when a "wetted" contact is used?
Will some PLC simply not function unless there is a dry contact?? (I would struggle to see how this can be--maybe there is a limitation on the frequency of the incoming electrical signal, that I can grasp).
Perhaps it is a way to protect the 3rd party's equipment--they want it on an isolated circuit in case the device sending the electrical signal shorted or had an issue...?
Oh ye electrical engineers! Please help my feeble mechanical mind...
Thanks!
Hand
I am a mechanical engineer with background in electronic packaging. I work in the water industry and there is a large need for water meters to send an electrical signal to an external device (usually PLC occasionally SCADA) to trigger an external valve, activate a pump, perform SOME type of mechanical action. This is usually required for some process--i.e. injecting chemicals into the stream (depending on the type and use of flow of course).
The issue I am having is--why would the owner/operator of the third party device specify a dry contact requirement? I see the value in the dry contact if there is no form of external power that can be applied to the device sending the electrical signal, but other than that I am struggling to see value.
Is there a safety issue when a "wetted" contact is used?
Will some PLC simply not function unless there is a dry contact?? (I would struggle to see how this can be--maybe there is a limitation on the frequency of the incoming electrical signal, that I can grasp).
Perhaps it is a way to protect the 3rd party's equipment--they want it on an isolated circuit in case the device sending the electrical signal shorted or had an issue...?
Oh ye electrical engineers! Please help my feeble mechanical mind...
Thanks!
Hand