Flashcards in Test 3 Deck (9)
Will both programmed and real-world relays, if latched, remain latched if power is lost and then restored?
Both will retain
Latching relays are normally used when it is necessary for:
Contacts to stay open and/or closed even though the coil is only energized for a short time.
Explain why an MCR is often used with off-delay timers.
So the circuit can be shut down completely without waiting for the OFF delay timers to timeout
An MCR can be used to control:
Selected circuit rungs.
When using PLCs, NEMA recommends that consideration be given to stop functions independent of the PLC. Explain briefly why this recommendation is made.
Hardware safety circuit should always be wired to a PLC to provide a STOP independent of the program.
Define the word retentive.
Keeps value after power loss
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