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electro mechanical relays

electro mechanical relays

electro mechanical relays

(OP)
What is the difference between a HCB relay, and a PMA relay? Don't the both monitor pilot wires between substation?

RE: electro mechanical relays

Download:

HCB:
http://library.abb.com/GLOBAL/SCOT/scot229.NSF/VerityDisplay/A81DFF02D462803AC1256EC900560A63/$File/HCB_IB41_971_3M.pdf
(copy and paste whole address)
The type HCB relay is a high speed pilot wire relay designed for the complete phase and ground protection of two and three terminal transmission lines.

PMA:
http://library.abb.com/GLOBAL/SCOT/scot229.NSF/VerityDisplay/3144D713492EE24385256EAF005A47C2/$File/IB41-973.5r%20%20%20%20%20RM.pdf
(copy and paste whole address)
Type PM and PMA Monitoring Relays provide continuous monitoring of a pilot-wire circuit to detect open circuits, short circuits, grounds, and wire reversal.

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RE: electro mechanical relays

We used to have that type of electromechanical pilot wire relay setup. I think we had HCB and PM-1.  Presumably PM-1 is similar to PMA.  

If memory serves me right, you need both an HCB and a PM-1 at each end (4 relays).  I remember the HCB takes the input of the three phase currents at one end.  The PM-1 somehow helps with the interface and transfer trip function.

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