Radio interference from downlights

[Richard Burns]

I have just had a customer who is getting radio interference (not sure if this is new or has been going on all the time)when one set of downlights in the Kitchen is turned on.

This is four 50W 12V downlights, they are wired with two 105W transformers in a kitchen cupboard each transformer supplying two downlights wired in flex.

I am initially assuming that because the flex run is over 2M this is the "antenna" causing the interference.
However if this is a new occurrence it may be the Tx breaking down.

If I replace the txs would this have no effect (or make things worse)?

would the better solution be to supply each downlight with its own local tx, utilising the existing flex reconnected to 230V, access a bit difficult but should be OK.

Am I barking up the wrong tree entirely?

Thanks

 

[Specialist]

Hi Richard: Can't you ditch 1 transformer at a time to see which 1 is causing the problem ?

 

[Octopus]

Is the radio interference on AM, FM or digital?

We get interference on our digital radio in the kitchen and its related to the boiler and whether or not the kettle is switched on at the plug!

 

[Marvo]

It's most likely one or both of the transformers, especially if their the electronic type. I don't see that the flex length on the ELV side would make a difference.

Is there a dimmer involved in this equation? if so is it leading or trailing edge or phase angle? Those are the usual suspects when it comes to RFI.

 

[Richard Burns]

At the time two of the lamps (on one tx were not working and so when this one connected no problem (but no current flow) the other one did cause the interference. switch off no buzzing, switch on buzzing (on the radio)

No dimmer but it is a 3 gang switch.

Not sure which channel radio was tuned to, but sounded pretty generic static.

 

[Marvo]

Is the Tx electronic or wire-wound inductive?

 

[Richard Burns]

Good point, they look like totally standard electronic transformers, only really read the rating and SELV bits.
They did not look too old few years maybe so probably electronic.

 

[telectrix]

rip the trannies out and fit GU10s, or move the radio to the karzi.

 

[Richard Burns]

rip the trannies out and fit GU10s, or move the radio to the karzi.

Best bet methinks, leave the radio off, no problem!

 

[Golden_Boy]

rip the trannies out and fit GU10s, or move the radio to the karzi.

Or fit a wound transformer instead of the switch modes you are useing at the moment!

 

[telectrix]

well, in cambridgeshire, you can't reeieve rock radio from manchester, so, as every other station is pants, radio is redundant down there. has nobody mentioned to the cambridgeshire inhabitants that we now have a new medium, it's called television. it's a sort of wireless with pictures, invented by a scotsman.

 

[Richard Burns]

well, in cambridgeshire, you can't reeieve rock radio from manchester, so, as every other station is pants, radio is redundant down there. has nobody mentioned to the cambridgeshire inhabitants that we now have a new medium, it's called television. it's a sort of wireless with pictures, invented by a scotsman.

Is that on my am band, I don't think my valves are glowing enough to receive that!

 

[Marvo]

Or fit a wound transformer instead of the switch modes you are useing at the moment!

Agreed, those SMPS's are cheap and compact but they're filthy dirty things from an electrical point of view. Wirewound Tx will sort it out.

 

[alarm man]

I have just had a customer who is getting radio interference (not sure if this is new or has been going on all the time)when one set of downlights in the Kitchen is turned on.

This is four 50W 12V downlights, they are wired with two 105W transformers in a kitchen cupboard each transformer supplying two downlights wired in flex.

I am initially assuming that because the flex run is over 2M this is the "antenna" causing the interference.
However if this is a new occurrence it may be the Tx breaking down.

If I replace the txs would this have no effect (or make things worse)?

would the better solution be to supply each downlight with its own local tx, utilising the existing flex reconnected to 230V, access a bit difficult but should be OK.

Am I barking up the wrong tree entirely?

Thanks

depending how easy it is swap the tranny's and see if the fault follows,you can get some strange frequencies with faulty lighting..

 

[Richard Burns]

I think I will swap out the Txs for new ones, replace the broken lamps and see if the problem recurs, failing that I will change the txs to wire wound for the whole block.
Not sure the customer would want GU10s as the rest are all MR11 (about 30 of them!), I could change them all but a bit costly.

 

[Richard Burns]

Huh, quick update, bought £100 of transformers, go in loaded for bear, just explaining to the daughter what the fault is, switch on the radio and then switch on the lights... absolute silence; no interference at all!! Feel like a total fool, but what can you do?

Thanks for your help.

 

[Marvo]

If the problem is intermittent maybe it's a loose connection somewhere on the circuit.

 

[topquark]

Or maybe someone has changed the radio channel