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Thread: 12V switching of mains

  1. #1
    Automated Home Jr Member
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    Default 12V switching of mains

    For some time I've wanted to use a 12V Pre-amp trigger to switch mains power to my 6 power amps.

    Marmitek in socket X10 devices are out as they won't handle the current.

    The obvious choice is a relay driving a 4 way extension socket, I might however need to implement a delay for each socket as the amps have quite a high in-rush current and I think switching all 6 on at once might trip the circuit breaker. (I'll have to check).

    Is there something commercially available or am I going to have to ask one of the more knowledgeable members to put something together for me?

    Tim

  2. #2
    Moderator toscal's Avatar
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    How much current are we talking about.
    I can get X10 mini modules (They are just slightly thicker than a micromodule hence mini module, they are also cheaper) that will cope with just over 2100W that's about 9.5amps at 220 Volts. The modules are also 2 way and have noise filtering built in.
    Or the din mounted AD10 cope with depending on the load type up to 16amps.

  3. #3
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    I'm going to have to get a plug in current monitor from Maplin to get a definitive answer but the amps are driven by 2x13 Amp 4 way plugs - each in different sockets but on the same ring main.

    The problem I had with the micro-module is that the amps are all Audiolab 8000 series which have HUGE torroidal transformers and therefore present an inductive load. I don't have any other X10 in the house, the only Automation I have is a Polaron lighting system linked in to a Texecom alarm panel.

    Tim

  4. #4
    Automated Home Guru JonS's Avatar
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    Idratek do a 4x13A DIN rail mounted set of relays. Unlike other relays in their range these are unfused. They do have 4 x volt free digital inputs (DI) so you could use your 12V signal via a relay or similar to trigger the DI and use a Reflex programme (firmware coded via a free PC program) to map the DIs to the 13A relays. IIRC the usual guidance from Idratek on inductive loads is to use a "snubber" close to the load to supress the transient spikes.
    HTH
    Jon

  5. #5
    Automated Home Legend TimH's Avatar
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    Tim,

    This might handle some of the requirements: http://www.apcc.com/resource/include...=documentation

    It's a "Switched Rack PDU" and the general blurb (http://www.apcc.com/products/family/index.cfm?id=70) says:
    This product can be configured as part of a complete Data Center or Server Room solution.
    See our InfraStruXure™ page for more details. Switched rack PDUs provide load metering combined with controlled on/off switching by individual outlets for remote power recycling, delayed power sequencing of equipment and outlet use management.
    Which sounds ideal, but I'm not sure how you'd get the outlets to come on in the first place. Maybe you could send the 12V trigger to your Polaron system then have that engage a relay to power the PDU itself. Once "on" the PDU would then energise it's outputs in sequence to avoid the high in-ruch currents.

    I presume you don't have enough spare relay outputs to do this wholly within Polaron?

    HTH,

    TimH.

  6. #6
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    Tim,

    I missed your reply as for some reason I didn't receive an email prompt.

    I've actually got a couple of 5A lighting sockets that I originally put in either side of the home cinema screen in case I wanted to put uplighters in. I'd completely forgotten about them, both are unused, and connected to a Polaron switched or dimmable 240V 5A circuit which I can control from anywhere in the house using Pronto via an RF/IR blaster in front of one of the Polaron IR receivers.

    That opens up a whole host of opportunities including the solution you suggested. Thank you so much for removing the "must use the 12V output from the Meridian" blinkers!

    Tim

  7. #7
    Automated Home Legend TimH's Avatar
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    No problem Tim - I'm glad you've got a solution

    Cheers,

    Tim.

  8. #8
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    I read through the manual but couldn't find a way of using either a 12V supply or an auxilliary mains supply. Maybe I was having a stupid day. I've got an alternative trigger method but still no definitive answer...

    Tim

  9. #9
    Automated Home Lurker
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    Default 2 examples of turning Mains on and off over USB

    Hi,

    Super4 Relay board www.tctec.net (not quite 6 amps though)
    And power board www.emx.net.au/homeautomation.htm

    melonpeach

  10. #10
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    I've finally got around to buying a Maplin plug in power and energy monitor and the results look better than I thought:

    Quiescent current of 3 amplifiers (half my stack) is 0.45 amps and the switch on current is 3A. In use they don't go above .5 amps. I know we are talking about small amounts of current in standby but it is still the equivalent of two 120W lamps burning all day.

    I reckon an AW12 is worth a try - it isn't going to cost me a fortune to rig up a test system, and if it works, fantastic. If it doesn't at least I know what I'm dealing with.

    Tim
    Last edited by TimMorris; 3rd August 2008 at 02:17 PM.

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