I am anxious not to burn out the relay that switches power to other
equipment by loading it with a valve power amp.
Can anyone recommend the source of a mains contactor that will switch on and
off a few amperes whilst drawing only minimal current?
UK based so 230v working required.

"db" wrote in message
...
I am anxious not to burn out the relay that switches power to other
equipment by loading it with a valve power amp.
Can anyone recommend the source of a mains contactor that will switch on
and
off a few amperes whilst drawing only minimal current?
UK based so 230v working required.




Look in the surplus market and get a solid-state relay. They usually work of
6-48Vdc and will switch 30A or more. They use triacs as the active component
and switch at the xero crossing of the mains so they are safe to use to feed
a transformer.


--

Woody

On Thu, 12 Feb 2004 18:22:23 +0000, Woody wrote:


"db" wrote in message
...
I am anxious not to burn out the relay that switches power to other
equipment by loading it with a valve power amp. Can anyone recommend the
source of a mains contactor that will switch on
and
off a few amperes whilst drawing only minimal current? UK based so 230v
working required.




Look in the surplus market and get a solid-state relay. They usually work
of 6-48Vdc and will switch 30A or more. They use triacs as the active
component and switch at the xero crossing of the mains so they are safe to
use to feed a transformer.

There is a problem with SSRs. They do not actually isolate the current, so
you still have to treat the output from them as "live" even when they are
switched off. They give a false sense of security. An ordinary "plug-in" 8
or 11 pin 10A rated relay would probably be fine in this case as many
modern designs of that rating have the required 3mm contact gap to provide
isolation. Don't worry about zero-voltage switching as this is irrelevent
for simple switching of a load like that. The ordinary power switch
doesn't use it! Use a suitably rated fuse (probably 6A max) of course, not
a 13A as this is beyond the current carrying capabilities of the relay!
Use 2 poles of the relay and switch neutral as well. That way you can
always just unplug the relay for true double-pole isolation.

--
Mick
http://www.nascom.info for Nascom & Gemini information
Also at http://www.mixtel.co.uk where the collection started.
Currently deserting M$ for linux... :-)

In article ,
db wrote:
I am anxious not to burn out the relay that switches power to other
equipment by loading it with a valve power amp. Can anyone recommend the
source of a mains contactor that will switch on and off a few amperes
whilst drawing only minimal current? UK based so 230v working required.

Perhaps the most 'standard' power relay is an octal plug in type. They
have DPDT contacts rated at 10 amps, and the coil operating current is
very low - under 10mA. A base with screw terminals is also available.

Maplin
Relay JG60 3.99, base JG54 1.99.

Or just about any electronics supplier, RS, CPC, Rapid etc.

A decent electrical wholesaler might even stock them too.

TLC do, if there's a branch near you.

--
*The problem with the world is that everyone is a few drinks behind *

Dave Plowman London SW 12
RIP Acorn

On Thu, 12 Feb 2004 16:08:06 +0000 (UTC), "db"
wrote:

I am anxious not to burn out the relay that switches power to other
equipment by loading it with a valve power amp.
Can anyone recommend the source of a mains contactor that will switch on and
off a few amperes whilst drawing only minimal current?
UK based so 230v working required.




Er.....have you considered using that convenient switch on your wall
outlet?

"db" wrote in message
...
I am anxious not to burn out the relay that switches power to other
equipment by loading it with a valve power amp.
Can anyone recommend the source of a mains contactor that will switch on
and
off a few amperes whilst drawing only minimal current?
UK based so 230v working required.

**Use a TRIAC, or a Solid State Relay. They're excellent for switching
inductive loads.


--
Trevor Wilson
www.rageaudio.com.au