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#164976 - 06/15/07 06:32 PM plug-in relay  
togol  Offline
Member
Joined: Sep 2005
Posts: 421
NW In. USA
my buddy "Biodiesel Man" had curbs put in at his home and somebody other than me talked him into installing ropelight in the curbs... about 400' worth of the stuff.

so I made him a little panel with the usual timer / PE and a little 8 pin relay.
the problem ???
the two ropelight circuits are a bit high.... 9A and 11A on a relay rated 10A.
I was thiking of adding a second relay and running each circuit through BOTH of the NO poles on a relay

sound stupid?

I could get a definite purpose contactor and jam it in the box ( there is a pond pump control in there too )

but I thnk the ice cubes would handle it by paralleling the feed through them.

a bit unorthodox, but it could work , right ?



Tom

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#164979 - 06/15/07 08:04 PM Re: plug-in relay [Re: togol]  
NJwirenut  Offline
Member
Joined: Sep 2001
Posts: 806
Bergen County, NJ
Not a good plan.

Inevitably, one set of contacts will close or open a millisecond or 2 before the other, and will erode at a much faster rate.

The best solution is a relay with properly rated contacts.


#164982 - 06/15/07 08:31 PM Re: plug-in relay [Re: NJwirenut]  
togol  Offline
Member
Joined: Sep 2005
Posts: 421
NW In. USA
NJ, your taking all the fun out of this..;


Tom

#164984 - 06/15/07 10:00 PM Re: plug-in relay [Re: togol]  
JoeTestingEngr  Offline
Member
Joined: Nov 2005
Posts: 785
Chicago, Il.
What about just driving the coil of an A/C control relay like this one.
http://www.grainger.com/Grainger/items/6X567
You won't come close to overloading those contacts.
Joe


#164986 - 06/15/07 10:32 PM Re: plug-in relay [Re: JoeTestingEngr]  
gfretwell  Online Content


Member
Joined: Jul 2004
Posts: 9,103
Estero,Fl,usa
Why not a solid state relay?


Greg Fretwell

#164992 - 06/16/07 01:41 AM Re: plug-in relay [Re: gfretwell]  
JoeTestingEngr  Offline
Member
Joined: Nov 2005
Posts: 785
Chicago, Il.
I thought about suggesting an SSR but a majority are 3-32 VDC control input and he doesn't need a DC supply for anything else. The AC control ones tend to be more expensive than the A/C relay that will carry more current and make sense to more people. Lastly, he can feed each string through it's own set of contacts and perhaps, separate fusing.

Greg, I knew that you would think of using an SSR just like I did. What I didn't know is if you are always reminded of SSRs in the bottom of Cartridge Module Drives, used to control spindle motors. That was the first place I encountered one back when each MB weighed more than a pound.
Joe


#164996 - 06/16/07 06:45 AM Re: plug-in relay [Re: togol]  
walrus  Offline
Member
Joined: Jul 2002
Posts: 680
Bangor Me. USA
You can get ice cubes with 20 amp rated contacts, maybe even 30 amp


#164997 - 06/16/07 07:37 AM Re: plug-in relay [Re: walrus]  
gibbonsseabee80  Offline
Member
Joined: Oct 2005
Posts: 40
Chesapeake, VA
I would go with gfretwell's idea. At work we have systems with relays controlling small magnetic contactors. This might prevent re-work or premature failor later on. Just a suggestion. I like square d because the coil is enclosed/hidden and quiet.
http://www.grainger.com/Grainger/items/2CF80


Brian Gibbons

#164998 - 06/16/07 07:49 AM Re: plug-in relay [Re: gibbonsseabee80]  
gibbonsseabee80  Offline
Member
Joined: Oct 2005
Posts: 40
Chesapeake, VA
Sorry I meant go with JoeTestingEngr's idea. Sorry about that Joe


Brian Gibbons

#164999 - 06/16/07 09:51 AM Re: plug-in relay [Re: gibbonsseabee80]  
Mountain Electrician  Offline
Junior Member
Joined: Oct 2006
Posts: 31
Maine, USA
A SSR would be a good choice for this application since space is an issue. Crydom is good, AC/DC control with high amp output available. A Crydom A1225 has AC control, 25 Amp output, and costs between 30 and 40 bucks. When you install it, put heatsink compound between the relay and the metal backplate or box or it may not last long. Properly installed, a SSR is a great spacesaver.


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