Johns correct. I'm not for sure what the relay looks like, but some had a set
screw on the armature which prevented it from fully closing. It was set for a
paper thin air gap. A small pieace of paper glued to the armature would work if
there's no setscrew. A DC relay has to rely on the resistance of the wire for
the voltage used to not burn out and create enough magnatism to pull in the
armature. An AC will have less turns due to the fact it acts like a primary of
a transformer to make a short explanation. Plus the DC relay again, will not
have the shunt.
Best,
Will
*********** REPLY SEPARATOR ***********
On 1/28/06 at 11:49 PM John Popelish wrote:
>Bill Turner wrote:
>
>> I wish I could remember exactly, but years ago I heard some advice
>> against using DC on AC relays. It had to do with the core getting
>> magnetized or something like that, which delayed dropout when power
>> was removed.
>
>Yes, DC relays often have a thin film of nonmagnetic material between
>the coil core and the armature (the iron part it attracts), to keep
>the remnance from getting strong enough to hold the relay closed after
>the coil is de energized. AC relays almost always have a solid copper
>shunt ring around half of the tip of the coil core, to retard the
>phase of the field through the surrounded fraction of the core, to
>produce two separate pulsing sections that take turns holding the
>armature down, so it doesn't buzz as the AC current goes through zero.
>
>If you want to experiment with your relay, I suggest you find (by
>experiment) what DC just pulls it in, and then put double that voltage
>across the coil for a while, and check for any signs of overheating.
>If there is none, That is about what I would use to activate the
>relay. If it sticks on, you will have to epoxy a dot of paper on the
>tip of the core or the armature where it touches the core. A few mils
>is usually enough.
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