Relays. What is the difference between SPCO & SPDT?

[leavemetogetonwithit]

Same relay, same manufacturer, same part number.
RS describes it as single pole double throw (SPDT)
Farnell calls it single pole change over (SPCO)
Why two terms for the same thing, or am I missing something?
Schrack / Tyco RT314024
Mike.

[electrofix]

Re: Relays. What is the difference between SPCO & SPDT?

they are the same thing just a different way of describing

change over relay changes over from 1 contact to the other

therfore has 2 positions so double throw

same action as a 2 way switch

hope this makes it clearer

Dave

[leavemetogetonwithit]

Re: Relays. What is the difference between SPCO & SPDT?

Strange. I always imagined a double throw meant there would be a midway position where neither contact was made, hence switch would need to be “thrown” twice to get from one side to the other. Couldn’t figure out how that would be achieved inside a single relay. Very annoying (to me) that there isn’t more standardisation of the terminology.
Mike.

[electrofix]

Re: Relays. What is the difference between SPCO & SPDT?

to do that in a relay would require 2 coils or using a dc coil and reversing polarity

dave

[leavemetogetonwithit]

Re: Relays. What is the difference between SPCO & SPDT?

Well thanks for the replies Dave. At least I now know I can go ahead with the order.
Mike.

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