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Gaugemaster Open Transformers

Image of MARTIN LOVELL.MARTIN LOVELL guides us through wiring open transformers.


Gaugemaster Open Transformer.

First of all, a WARNING.

Using these open transformers (GMC-T1-T6) requires high levels of protection when used on a layout, as terminals receiving mains electricity are exposed, so make sure the transformer is NOT in a position where you can inadvertently touch the exposed terminals.

Shielding the transformer with a wooden or plastic case is a good idea, but make sure the unit is well ventilated, in order to prevent overheating. You can use our Transformer fitting kits to make the whole process easier.

During the next stage of the operation, make ABSOLUTELY CERTAIN that the mains wire you are using is NOT plugged into the mains - Not even if the socket is switched off! Double check this. The mains wire, from a 3amp fused plug, is connected to the transformer input terminals and chassis using the following configuration:

Gaugemaster Open Transformer.

  • LIVE (BROWN WIRE) to one of the IN terminals
  • NEUTRAL(BLUE WIRE) to the other.
  • EARTH (GREEN AND YELLOW) is connected to the body or chassis of the transformer.

These connections should be soldered, not just wrapped round the terminals. This is to prevent a short circuit on the mains in the event of one of the wires coming off and touching the other, blacking out the house electrics, or (in the worst case scenario) the hall holding a model railway exhibition! Please note - all connections made during the installation process should be soldered.

Gaugemaster Open Transformer.

The easiest way to attach the earth to the transformer is to wrap it around the fixing screw and hold it in place with a washer.

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The output side, i.e. the wires going to the controller or similar, are wired as follows:

Gaugemaster Open Transformer.

  • One wire will connect directly to one of the output terminals and then to one of the controller inputs, whilst the other wire is connected to one leg of a thermal cut-out (GM41) then to the other input of the controller. The other leg of this cut-out is connected to the other output terminal of the transformer. The thermal cut-out unit prevents overheating or burnout in the event of a short circuit on the controller or track. You will require one of these cutouts per output, therefore 2 in the case of the T1 transformer.

    Once again though, I will stress that you are working with a unit that does feature exposed 240 volt mains electricity - so if you are at all uncertain of the safety aspect have a word with a qualified electrician, or use a Closed Transformer such as the GMC-M1, where all the safety features are provided for you.

    Safe and Happy modelling.


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