Reading and Combining Protective Trip Contacts
Reading and Combining Protective Trip Contacts
(OP)
I have about a dozen auxilliary trip contacts for a small generator for such things as low hydraulic oil pressure, exciter diode failure, things of that nature. These will all trip a lock-out relay (LOR) but I'd also like to get status via a PLC so there will be immediate indication of what caused the trip. I have only one contact for each. I see two ways to do this:
1) Auctioneer the contacts with diodes so they are segregated into PLC inputs but combined to trip the LOR
2) Read the contacts on the PLC and setup an immediate I/O scheme (essentially an interrupt) that will trigger and output that trips the LOR.
The second scheme relies on the PLC for some of the protection. Any thoughts on a preferred method?
1) Auctioneer the contacts with diodes so they are segregated into PLC inputs but combined to trip the LOR
2) Read the contacts on the PLC and setup an immediate I/O scheme (essentially an interrupt) that will trigger and output that trips the LOR.
The second scheme relies on the PLC for some of the protection. Any thoughts on a preferred method?





RE: Reading and Combining Protective Trip Contacts
RE: Reading and Combining Protective Trip Contacts
What do you mean by "Auctioneer the contacts with diodes..."?
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RE: Reading and Combining Protective Trip Contacts
RE: Reading and Combining Protective Trip Contacts
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: Reading and Combining Protective Trip Contacts
Our circuits look like the second diagram above, but without the pull down resistor. The LOR coil (at the shutdown position above) has a low enough impedance that the resistor isn't required.