Re: (ET) relays

["harry landis" <hlandis hotmail com>]

An AC coil just has a slightly different arrangement of the iron core so it 
won't buzz. So you can use an AC coil on DC, no problem, but a DC relay will 
buzz on AC. And since the coil is an inductance, it acts like an extra 
impedance in series with the coil resistance to the AC voltage, but not to 
DC voltage. So the required AC voltage to actuate the relay is higher than 
the DC voltage for the same relay. So it turns out that most all 110VAC 
relays work just about perfectly on 36V DC. But it is a good idea to measure 
the coil current on DC and make sure it is not much more than the AC current 
just to be sure.

Harry Landis

From: "RJ Kanary" <rjkanary nauticom net>
To: "ET" <elec-trak cosmos phy tufts edu>, "Tim Humphrey" <hump evgrin com>
Subject: Re: (ET) relays
Date: Thu, 14 Jun 2007 08:38:51 -0400

Is the diode 'across' the coil, or in series with the coil?

RJ


----- Original Message -----
From: "Tim Humphrey" <hump evgrin com>
To: "ET" <elec-trak cosmos phy tufts edu>
Sent: Thursday, June 14, 2007 7:26 AM
Subject: Re: (ET) relays


>
> relays will usually have two sets of ratings, one for the coil and one 
for
> the contacts.
>
> AFAIK (as far as I know) a relay coil can only work on DC, otherwise it 
is
> a buzzer. So a coil rated for 24vac would have a diode integrated in its
> windings in order to convert the incoming ac into dc. It obviously would
> work on dc, but you would have to observe polarity.  (I'm thinking I'm
> about to learn something new; "to me").
>
> Is there any other markings on it to identify it?
>
> --
> Stay Charged!
> Hump
> I-5, Blossvale NY
>
>
>>
>> -----Original Message-----
>> From: elec-trak-bounces cosmos phy tufts edu
>> [mailto:elec-trak-bounces cosmos phy tufts edu] On Behalf Of Neil Dennis
>> Sent: Wednesday, June 13, 2007 6:31 PM
>> To: et
>> Subject: (ET) relays
>>
>> I picked up some  "open" relays that look like the RTN ones on my e12
>> today that are listed as AC with an ohms rating for the coil.  Wonder if
>>
>> they are usable on DC ?
>>
>> wombat
>>
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>
>
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