In article .com,
Steve wrote:
How does an AC relay work? I understand that the magnetic field of a
DC relay coil attracts the contact arm and I assumed an AC relay just
had a diode to convert coil current to DC - however when I tried to
find an AC relay fault there was no diode. I thought 50 or 60 Hz
alternating magnetic field cannot produce such a corresponding
movement in a mechanical contact arm so I would have thought the net
magnetic effect would be zero (no overall attraction or repulsion).
Given the relay obviously operated before, I just can't see how. I
did think the 'AC' rating just meant the contacts but I don't see why
this wouldn't just be a current rating.

AC coil relays are common. A magnet of any type will attract a magnetic
substance regardless of polarity - it's just if the second substance is -
or gets - magnetized that they can repel. So you use a low permeability
substance for the armature. Something like soft iron.

--
*Gaffer tape - The Force, light and dark sides - holds the universe together*

Dave Plowman London SW
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