Step up Transformer?

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mwm1752

mwm1752

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Just not getting this & is a weak point for me - single phase 120/240v step up to 240/480v -- Looking at the wiring diagram for a grounded conductor connection point. Looks like the grounded conductor should not be attached to the windings but instead to the frame connection. I'd rather not approve & learn than approve a mistake.
 

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What voltage are you supplying ? What voltage do you want on the output ?
 
In general you do not want to _supply_ a neutral conductor to a transformer _primary_ connection. The transformer itself will 'derive' the neutral voltage and by connecting the supply neutral to the transformer primary neutral you have essentially created a short circuit between two different supply terminals that are at approximately the same voltage.

Assuming that the supply is 120/240V and the desired _output_ is 480V:

The feeder to this transformer should have two 'hot' conductors going to X1 and X4 and a ground wire going to the frame. No grounded circuit conductor needed.

Coming out of this transformer you have H1 and H2, and as shown in the picture the HV side is ungrounded, meaning that a ground fault will not trip a breaker and you probably need ground fault detection. You might be able to ground from the high side center tap, but I would check with the transformer manufacturer to see if this is permitted.

-Jon
 
mwm1752 said:
Just not getting this & is a weak point for me - single phase 120/240v step up to 240/480v -- Looking at the wiring diagram for a grounded conductor connection point. Looks like the grounded conductor should not be attached to the windings but instead to the frame connection. I'd rather not approve & learn than approve a mistake.
Click to expand...

Interesting, the wiring picture does not look like a step up transformer, as the neutral would not be needed. This transformer is a 480 volt primary (no 240 volt) and 120/240 volt secondary. I'm also pretty sure the second picture of a nameplate is not off the same transformer as the first picture. If you are looking to step up 240 volt to 480 volt single phase, then no grounded/neutral conductors are needed.
 
240 in Interconnect X2 & X3 ..... 240 to X1 and X4 Ignore neutral (120v)
480 out H1 and H2

Note winnie's comment on ground detectors/grounding
 
infinity said:
I can't see making field connections to the tap points on the coil. Sounds like he want a 240-240/480 step-up transformer which is not what he has.
Click to expand...

240/480 is not a voltage configuration I've ever heard of.

JAP>
 
The transformer shown was clearly designed to be a 240 or 480V primary to 120V or 120/240V step down transformer.

It may be usable in 'reverse' to step 240V up to 480V.

The 'taps' on the high voltage side are probably not suitable for field connections to an output to get a midpoint ground on the 480V, nor to provide a neutral for 240/480V. However it is worth contacting the manufacturer; perhaps there is some sort of terminal kit or wire harness that would permit this usage.

-Jon
 
winnie said:
The transformer shown was clearly designed to be a 240 or 480V primary to 120V or 120/240V step down transformer.

It may be usable in 'reverse' to step 240V up to 480V.

The 'taps' on the high voltage side are probably not suitable for field connections to an output to get a midpoint ground on the 480V, nor to provide a neutral for 240/480V. However it is worth contacting the manufacturer; perhaps there is some sort of terminal kit or wire harness that would permit this usage.

-Jon
Click to expand...


:thumbsup:
 
Although what voltage configuration would a neutral give to a 480v single phase output that would even be useable ?

JAP>
 
What would you use 480V on that only would be supplied by two legs? your not going to get 3phase out of a single phase XFMR.
 
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