Replacement for a transformer block powering wire track lighting

[ericbamford]

I need to replace a transformer block powering cable track lighting for 4 X 20W halogen bulbs. The existing block can be seen here: http://Marine Power Co Ltd AC Adaptor 230V to 12V, and has the following info on the label PRI: 230V~50Hz 135W 0.58A; SEC: 12V~105VA 8.75A. Would this transformer: Transformer for halogen light bulb 230 V to 12 V (PRI: 220-240V~50/60Hz; SEC: 11.5V#eff.105VA) work as a suitable replacement? I can't find an exact replacement for the original block so want to make sure I'm getting the best alternative. And perhaps one that doesn't weigh approx three tons like the original!

 

[Geoff1946]

Yes, that would be OK.   Alternatively you could take the opportunity to change it to led with an led driver and four new led lamps.

 

[BorisJ]

I need to replace a transformer block powering cable track lighting for 4 X 20W halogen bulbs. The existing block can be seen here: http://Marine Power Co Ltd AC Adaptor 230V to 12V, and has the following info on the label PRI: 230V~50Hz 135W 0.58A; SEC: 12V~105VA 8.75A. Would this transformer: Transformer for halogen light bulb 230 V to 12 V (PRI: 220-240V~50/60Hz; SEC: 11.5V#eff.105VA) work as a suitable replacement? I can't find an exact replacement for the original block so want to make sure I'm getting the best alternative. And perhaps one that doesn't weigh approx three tons like the original!

If it is track lighting you must not that so called 'transformer for halogen light bulb'. That is actually a switch mode device designed for short wire lengths. With the long wires on track lighting it will cause serious electromagnetic interference.

You have to use a genuine wire wound transformer. Something like this:

https://www.tlc-direct.co.uk/Products/LTWP100.html

Out of interest what is wrong with the original one?

 

[Geoff1946]

If it is track lighting you must not that so called 'transformer for halogen light bulb'. That is actually a switch mode device designed for short wire lengths. With the long wires on track lighting it will cause serious electromagnetic interference.

Is that true?  I'll hold my hand up if it is but I've never seen any documentation to limit cable length from those transformers/drivers to halogens.

 

[BorisJ]

Is that true?  I'll hold my hand up if it is but I've never seen any documentation to limit cable length from those transformers/drivers to halogens.

Yes it is. There was a case a while back (I can't remember where I read it) of a shop where a sparks changed a transformer feeding a cable track for a switch mode supply as they wanted to be able to dim it. It was a coastal town and there were immediate complaints as marine radio was being affected. A visit from Ofcom interference investigators followed and the offending switch mode was quickly removed.

 

[Geoff1946]

Interesting, but I would suggest that the issue in your example is badly designed equipment which, if properly tested wouldn't meet the mandatory EMC emissions standards?

I'm not saying you are wrong but I think it may be a limited problem.

The average home must have a dozen or more SM units, many of them wall-warts with a couple of metres of lead to the appliance. Some of these will have the little ferrite bobbin on the lead, some not.

In my conservatory I have five metres of led strip running off a five amp switch mode unit. The radio below suffers no effects though I admit the AM bands are not used now.

 

[BorisJ]

SM units with a DC output shouldn't be a problem. All the RF will (hopefully) be eliminated with the rectification and smoothing.

The halogen supplies output AC in tens of kHz, along with their harmonics. Have not done any tests myself apart from looking at the output on a scope. The frequency and waveform changes with load.

 

[Sidewinder]

A wire-wound transformer will output nothing but 50Hz sinewave.

A switched more PSU will output all sorts of noise.

I don't believe for a minute that the unit that caused the interference with the maritime radio met the EMC directive.  Which unfortunately would be extremely common.