Transformer assistance needed (old installation) Need to talk about install.

[Kyell]

Gentleman and fellow electrician's,

I find myself in need of help, I have been tasked to install an old transformer, which in my opinion was improperly removed from one location and installed in a new one. I was tasked my my superiors to wire this single phase transformer, I have in excess of 22 years experience in the electrical trade and while I believe my knowledge is good I am having a crisis in my confidence since I did not demo this transformer myself and it is REALLY poorly marked( I will attach cover photo) my strongest question is where is my XO terminal since it it NOT marked in anyway.

I have managed to recover most of the markings but not all I am really not happy with this transformer for other reasons it shows signs of being overheated as well.

Professionally yours,
Bob

PS having great difficulty attaching file, can anyone assist?

 

[Dennis Alwon]

The forum limit is 145kb so if the file is larger it is best to put it on an online site such as google drive and give the link.

If it is an image then use the image icon above

 

[ActionDave]

Welcome to the forum.

A single phase transformer should not have an XO, just X1, X2, X3, and X4. Can you see the windings or are they packed in sand?

Attaching a photo can be a pain. I get my kid to help.

 

[Kyell]

Thank you for the welcome.

Thank you for the welcome.

I have been a member before but I was out of the trade doing work as an Engineering Assistant, creating and correcting drawing for the Engineers. It helped having my experience with code and electrical systems to do this job, recently I was requested to do this job for the Engineers I work for, it is an addition or better said a re-tasking of an existing structure 24 X 36 garage. Since this is and was a large industrial complex the existing 3 phase 277/480 panel is here and in good shape. However the electrician who was doing the job was fired by the owner, I was asked if I still had the skills to finish. I accepted. I believe I have found the needed information from notes of a job I did about 6 years ago. (yes I keep records, I am a bit OCD that way). So here is was I have

replace missing jumper between x2 and x3
This will give me X1 to X4 240 volts

x2 and x3: 120v to ground

I still think I am missing something it seems to me X2 to X3 jumper should have been bonded to ground to form my neutral (not in my notes) sorry way to used the 480/277 to 208/120 it has me rusty and soft. Does this help make sense?

Bob

 

[ActionDave]

I have been a member before but I was out of the trade doing work as an Engineering Assistant, creating and correcting drawing for the Engineers. It helped having my experience with code and electrical systems to do this job, recently I was requested to do this job for the Engineers I work for, it is an addition or better said a re-tasking of an existing structure 24 X 36 garage. Since this is and was a large industrial complex the existing 3 phase 277/480 panel is here and in good shape. However the electrician who was doing the job was fired by the owner, I was asked if I still had the skills to finish. I accepted. I believe I have found the needed information from notes of a job I did about 6 years ago. (yes I keep records, I am a bit OCD that way). So here is was I have

replace missing jumper between x2 and x3
This will give me X1 to X4 240 volts

x2 and x3: 120v to ground

I still think I am missing something it seems to me X2 to X3 jumper should have been bonded to ground to form my neutral (not in my notes) sorry way to used the 480/277 to 208/120 it has me rusty and soft. Does this help make sense?

Bob

Yes it make sense. You don't have 120V to ground yet. You need to bond your X2 and X3 to the transformer case or the first disconnect and run a grounding electrode conductor there. Then you will have your 120V to ground.

250.30 the NEC is where to look. If you have access to the handbook there are some good illustrations. I think there is some at Mike Holt.com too.