Re: (ET) relays

[Klein Robert W NPRI <KleinRW Npt NUWC Navy Mil>]

Damn I love this stuff.  The more I learn the dumber I feel.  Thanks and 
keep it coming!

Bob Klein 

-----Original Message-----
From: elec-trak-bounces cosmos phy tufts edu [mailto:elec-trak-bounces 
cosmos phy tufts edu] On Behalf Of harry landis
Sent: Thursday, June 14, 2007 9:13 AM
To: elec-trak cosmos phy tufts edu
Subject: Re: (ET) relays

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
 >>
 >> _______________________________________________
 >> Elec-trak mailing list
 >> Elec-trak cosmos phy tufts edu
 >> https://cosmos.phy.tufts.edu/mailman/listinfo/elec-trak
 >
 >
 >
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 >


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