grounding buck boost transformer

[troyaenderle]

Heres the cenario, going from 277 volts to 120 volts. single phase, schematics show tieing nutral and hot 277 to H leads hot and nueltral out to x;s for 120 v , pulled ground from panel to ground lug in transformer( not bonded) through transformer to first box. Have 120 volts hot to nuetral, not voltage from hot to ground, even though the ground is actually tied trough the transformer can to the main panel that does have good ground. I have always bonded ground to nuetral in transformers but was told not to from the manufacture of this little transformer. Has anyone heard of this before?

 

[buddhakii]

I believe a buck boost is not seperatly derived depending on the field connections. Check out the diagram and see if the neutral in and neutral out are physically connected together, I bet they are which would make this an autotransformer. By the way, your transformer can is bonded. There is just no mbj.

 

[troyaenderle]

Thanks but I am still wondering why I have no ground,, The schematic on the secondary side only says { secondary 120: interconect x1 to x3 and x2 to x4 , secondary line voltage to x1-x4 {being x1 as hot and x4 as nuetral} so to me the nuetrals in and out are not connected together physically,,am I having a brain fart and not reading this right?

 

[hillbilly1]

Are you sure it's a buck/boost? Normally with that voltage range it will be a standard step up/step down transformer with Isolated windings. Buck/boost transformers are usually wired as an autotransformer.

 

[RUWired]

Thanks but I am still wondering why I have no ground,, ?

You don't have any reference to ground because it is a seperately derived system and you didn't make the bond from x2/x4 to the frame. Usually this is made for ground fault protection, not sure why the installation is not calling for it unless it is supplying electronic equipment.

 

[templdl]

Can you post the wiring diagram for what you are attempting to do? It may simpify trying to answer your question.