Re: Low Voltage Lighting transformer problem

[Ian Shef <invalid@xxxxxxxxxxxxx>]

Ben Mack <nospam@xxxxxxxxxxxxxxxxxxxx> wrote in news:xJ
$M8oCS3zTEFwlj@xxxxxxxxxxxxxxxxxxxxxxxxx:

> Hi
>
> I've installed some 12V halogen lights in some shelves, such that I have
> to mount the transformer remotely. I used 3m of normal 1.5mm^2 lighting
> cable to connect the transformer to the lights, having calculated a
> 300mV drop across the cable (30mV/A/m x 3.3A x 3m)
>
> However in practise I'm losing around 6V in the cable, and have
> discovered that the transformer output is 125kHz, not 50Hz, explaining
> the bad attenuation in the cable
>
> So my question is - do all compact dimmable 12V transformers have high
> frequency outputs?
>
> I don't have space for an old-fashioned 50Hz transformer
>
> Cheers

I suspect that something else is wrong.  I don't know what gauge wire
corresponds to 1.5mm^2, but if you were expecting 300 mV drop on ordinary
lighting wire at 50 Hz, there shouldn't be that much more at 125KHz.

As an experiment, use a short wire to put the "transformer" very close to
the lights and see what happens.  It could be that the "transformer" can't
handle this load or is broken.

If the transformer is OK, then solutions include:
Heavier wire.
More wires in parallel.
Separate wires from the "transformer" to each light.
Twist the two wires to each other to lower the inductance.  (probably not
very effective at this frequency)

Good luck!

--
Ian Shef     805/F6      *    These are my personal opinions
Raytheon Company         *    and not those of my employer.
PO Box 11337             *
Tucson, AZ 85734-1337    *