Relay ratings

[Rylos]

Hello All,

I have a relay which has a rating of 1A at 24VDC. The current rating is
pretty obvious but is the voltage rating the maximum open circuit voltage
across it's terminals? Thanks.

-Dave

 

[CFoley1064]

Subject: Relay ratings
From: "Rylos" unknown
Date: 9/14/2004 10:29 AM Central Daylight Time
Message-id: <XdSdnbYEu-f5k9rcRVn-rg@buckeye-express.com

Hello All,

I have a relay which has a rating of 1A at 24VDC. The current rating is
pretty obvious but is the voltage rating the maximum open circuit voltage
across it's terminals? Thanks.

-Dave

The relay is rated to switch a 24VDC resistive load at 1 amp for the
manufacturer-specified number of times before failure. That number can be
anywhere between 20,000 and millions, depending on the spec sheet. If you use
a higher DC voltage, you will get excessive arcing at contact open/close, which
will reduce life, pit the relay contacts and possibly cause them to spot weld
together on make. Usually it's rated that way because of contact separation
and contact separation speed.

Good luck
Chris

 

[Rylos]

Thanks Chris,

If the load I'm switching is lower than 24VDC, actually it's 5 can you push
more amperage through or is the 1A rating just 1A regardless?

-Dave

CFoley1064 <cfoley1064@aol.com> wrote in message
news:20040914162923.19417.00000554@mb-m22.aol.com...

Subject: Relay ratings
From: "Rylos" unknown
Date: 9/14/2004 10:29 AM Central Daylight Time
Message-id: <XdSdnbYEu-f5k9rcRVn-rg@buckeye-express.com

Hello All,

I have a relay which has a rating of 1A at 24VDC. The current rating is
pretty obvious but is the voltage rating the maximum open circuit voltage
across it's terminals? Thanks.

-Dave


The relay is rated to switch a 24VDC resistive load at 1 amp for the
manufacturer-specified number of times before failure. That number can be
anywhere between 20,000 and millions, depending on the spec sheet. If you
use
a higher DC voltage, you will get excessive arcing at contact open/close,
which
will reduce life, pit the relay contacts and possibly cause them to spot
weld
together on make. Usually it's rated that way because of contact
separation
and contact separation speed.

Good luck
Chris

 

[Peter Bennett]

On Tue, 14 Sep 2004 19:08:34 -0400, "Rylos" <unknown> wrote:

Thanks Chris,

If the load I'm switching is lower than 24VDC, actually it's 5 can you push
more amperage through or is the 1A rating just 1A regardless?

-Dave

Relay contact ratings work just like switch ratings.

In this case, the contacts can safely handle up to 1 amp, at up to 24
volts DC.

--
Peter Bennett, VE7CEI
peterbb4 (at) interchange.ubc.ca
new newsgroup users info : http://vancouver-webpages.com/nnq
GPS and NMEA info: http://vancouver-webpages.com/peter
Vancouver Power Squadron: http://vancouver.powersquadron.ca

 

[CFoley1064]

Subject: Re: Relay ratings
From: "Rylos" unknown
Date: 9/14/2004 6:08 PM Central Daylight Time
Message-id: <8oKdnXUOYYF95NrcRVn-jA@buckeye-express.com

Thanks Chris,

If the load I'm switching is lower than 24VDC, actually it's 5 can you push
more amperage through or is the 1A rating just 1A regardless?

-Dave

You can't push 500% more than rated current through the relay and expect it to
survive for long. A lower DC voltage won't help.

There is one possibility of getting more, but I don't think it will be 5 times.
Just like a switch, relays have a published rating for switching current, and
another (almost always non-published) rating for holding current. If you're
not going to use the relay to switch the load on and off, you could probably
get more (say, 20% to 100% more, depending), but certainly not 5A. Guess you
need another relay to do the job. They're not expensive, and that's what I'd
do.

Of course, you might just try it and see what happens. You might get anywhere
from 1/2 (on, but no off -- contacts welded) to hundreds of uses out of the
relay, particularly if it's a purely resistive load. No guarantees, though. A
1A relay is pretty weak for a 5A load.

Good luck
Chris