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Topic Title: Multi Voltage Relay
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Created On: 17 December 2012 06:18 PM
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 17 December 2012 06:18 PM
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primo

Posts: 454
Joined: 10 January 2008

I'm after a multi voltage relay. It is to trigger a fan switched via a dimmer. When the dimmer is dimmed down there is not enough voltage to keep the coil in. So I'm looking for the coil to operate between 50v - 240v.

I've found THIS but it's all getting rather expensive but does look like it will do the job but it's all getting rather expensive! And ideally I need it to fit inside a single surface box.

Has anyone used anything similar or any other ideas how to trigger the fan (it won't activate through the dimmer alone).

Thanks
 17 December 2012 06:27 PM
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OMS

Posts: 19837
Joined: 23 March 2004

Does the dimmer have an L2 contact (ie 2 way) - if so, use that with a N/C relay for the fan - with the switch off (ie L2 live), the relay is forced open, when you close the switch to allow dimming of the lighting load the relay goes closed (loss of supply) and the fan operates ?

Regards

OMS

-------------------------
Failure is always an option

Edited: 17 December 2012 at 06:43 PM by OMS
 17 December 2012 06:44 PM
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primo

Posts: 454
Joined: 10 January 2008

Thanks, a great idea but unfortunately I don't have a spare core available from the switch to do this and apparently you're not allowed to use the CPC as a live conductor!
 17 December 2012 06:54 PM
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OMS

Posts: 19837
Joined: 23 March 2004

LoL - bit of brown sleeving - what is it they say about it being easier to get forgiveness than permission

OK - so no spare core then - wireless switch to a receiver near the fan ?

Regards

OMS

-------------------------
Failure is always an option
 17 December 2012 07:35 PM
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GB

Posts: 364
Joined: 04 September 2002

Why not control the fan via an occupancy sensor ceiling mounted!! picking the cabling up from the ceiling of floor void.
Can you change the fan to one with a PIR attached?
 18 December 2012 12:15 AM
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alancapon

Posts: 5808
Joined: 27 December 2005

Using a relay as you suggested may not actually work. All dimmers work by chopping the mains frequency, such that power flows for only part of the cycle. At low brightness, the lamp is only illuminated for a small part of each cycle. I cannot predict how the relay you have found will operate with this sort of waveform.

Regards,

Alan.
 18 December 2012 07:32 AM
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primo

Posts: 454
Joined: 10 January 2008

Thanks all. I think the integral PIR could be the way to go with this one. Cheers.
 18 December 2012 04:01 PM
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broadgage

Posts: 1344
Joined: 07 August 2007

What about a 12 volt relay worked from a small switched mode power supply.
If you get a multi voltage switched mode power supply rated for 90 volts to 250 volts, this will provide a regulated 12 volt DC output down to very low dimmer settings.
If not heavily loaded they work with an input below the stated minimum and tolerate the chopped waveform well.
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