CT Transformer Question

[SparTech]

I'm trying to learn about transformers. I needed a 120VAC to 24VCT transformer for a project. I ordered a transformer form one of the online suppliers. It is a 115/230VAC 50-60Hz to 24VCT. It has three leads on input instead of 2. The 3rd lead on the input was not shown on my schematic. Kinda threw me off. I want to use a 110VAC supply. Is the transformer for 230 supply only, or can it be for 110 as well? Did I order the wrong dad-gum transformer?

 

[(*steve*)]

There are three leads on the input side because you need to select the correct wires for 115V vs 230V.

It's somewhat surprising there's not 4 leads.

As to which leads to use, read the documentation or contact the supplier as your first options.

Otherwise reading the resistance between pairs of wires on the primary, you will probably find one pair with a resistance about twice that of the other two combinations. PROBABLY either one with the lower resistance will work fine for 110V, the higher resistance one for 230V. Beware that the will be a high voltage on the unused lead.

 

[SparTech]

Thank you, Steve. There are two white leads and one black lead on the input. I will ohm the leads ike you said to be sure.

 

[(*steve*)]

My guess is that white to white will be double the resistance of either black to white.

 

[SparTech]

You are absolutely correct, good sir. Now to build my bridge rectifier!