LV Transformers & Radio Interference

[exdevonboy]

Hi all,
A customer has recently replaced some of his 12V MR16 down-lighter bulbs with LED bulbs instead. One of the transformers (which were old) failed a month or so after he installed the new bulbs and I was asked to replace both of his existing LV transformers. They supply 4 No downlighters in a sort of pelmet shelf just below ceiling level.

When I replaced the transformers, I installed LED compatible versions. However, my customer has just rung me to say that his radio (on the worktop just below some of the lights) now turns itself off or retunes itself whenever the lights are turned on which he finds a bit annoying! Clearly a bit of RF interference going on which I assume is caused by the new transformers? Its not the LED's themselves as the radio was OK until the transformers were replaced.

The radio (only about 2 years old) works fine elsewhere in the house when lights are turned on.

Apart from trying a different make of transformer or even using a 'normal' (non-LED compatible) transformer, I'm at a bit of a loss why this is happening? Anyone else come across this type of issue before? Maybe the new transformer is faulty?

Any advice appreciated. Thanks.

 

[Barry White]

It will be the lamps its suprising common see below

Problems with LED bulbs and DAB radio - http://www.telegraph.co.uk/technology/advice/11312589/Problems-with-LED-bulbs-and-DAB-radio.html
LED bulb radio interference - has it happened to you? - https://conversation.which.co.uk/technology/led-bulb-radio-interference-dab-test/
LED lamps interfering with radio transmissions - LeapFrogLighting - http://www.leapfroglighting.com/led-lamps-interfering-with-radio-transmissions/

 

[Lucien Nunes]

Those links all seem to relate to mains-voltage lamps with internal electronic switching power supplies. In this case the switch-mode devices are the external 'transformers' and it is quite likely that the interference is coming from them and being radiated by the ELV cables to the luminaires. Electronic transformers of less than top-notch quality are likely to emit more interference as the makers save money by omitting or downsizing the interference filtering components, so if you have any suspicions you might first swap them to a different brand. But also check the max. permitted cable length for each model; if the existing cables are too long then they might emit too much interference. If the lamps are suitable for 50Hz AC then wirewound transformers (which create no interference) might solve the problem without altering the wiring, or if 12V DC then constant voltage DC drivers might give less interference.

 

[exdevonboy]

Thanks for your help.
Will visit the customer this week and try out some of your ideas!