Transformer letters

[3marcus3]

What are the letters used on the 120volt side of a transformer if you are stepping it up?

 

[augie47]

Are you asking which "X" leads are used to connect your 120 volt source ?
Is the transformer secondary single phase or three phase ? 240/120 ? 208/120 ?

 

[jim dungar]

In general for transformers, by convention, X means low voltage connections and H means high voltage.

However there are some manufacturers that do not follow this convention (in particular Current Transformers), instead they use H for primary and X for secondary.

So, you need to looke at the namplate wiring instructions and not just the terminal IDs.

 

[3marcus3]

I'm wondering when its on a test, and 120/240 is the primary and you are stepping up to 480. Is the 120/240 volt letter X or H?

 

[jim dungar]

I'm wondering when its on a test, and 120/240 is the primary and you are stepping up to 480. Is the 120/240 volt letter X or H?

The ANSI standard is for power transformers is: H = high voltage and X = low voltage.

But there is no guarantee this applies to your device, although it probably does because you are saying the voltage is 120/240V which is not a standard primary voltage designation.

What does your nameplate say for wiring?
Why do you care?