Neutral from secondary side of a transformer

[flee89]

I had a question regarding the neutral wire on the secondary side of a transformer. When connecting H2 and H3 in series, H1 and H4 can be fed 480V to step it down to 120V. On the secondary side, I understand having to connect X4 and X2 together, and X3 and X1 together, putting them in parallel to get 120V. My question is, does X4/X2 become a neutral wire or X3/X1? I've seen a project where X3/X1 was used as neutral in a schematic, but I can't figure out why. Did they ground it? Did they just choose that as neutral while deciding X4/X2 would be their hot wire? Or is it because X4/X2 leads X3/X1? Please let me know and thank you in advance for the help

 

[Avo Mk8]

So this is an isolating transformer with two 240V primaries, which are connected in series to 480V, and the transformer has two 120V secondaries that are connected in parallel (to maximise the current that can be drawn). On the secondary side I don't believe it matters which you choose to use as neutral, unless the transformer manufacturer has stated otherwise.
If you connected the two secondaries in series, to give 120 (X1) - 0 (X2, X3) - 120 (X4), then obviously the 0V would be neutral!

 

[pc1966]

I think the OP is USA based so maybe one for @Megawatt ?

 

[Lucien Nunes]

If the secondaries are in parallel so that there are just two wires leaving the transformer, the only difference between grounding X2/X4 to make it the neutral vs. grounding X1/X3, is whether the hot output is in phase with supply H1 or H3. Unless there are multiple transformers serving the equipment that need to be in-phase with each other, it won't make any difference.

 

[Megawatt]

I had a question regarding the neutral wire on the secondary side of a transformer. When connecting H2 and H3 in series, H1 and H4 can be fed 480V to step it down to 120V. On the secondary side, I understand having to connect X4 and X2 together, and X3 and X1 together, putting them in parallel to get 120V. My question is, does X4/X2 become a neutral wire or X3/X1? I've seen a project where X3/X1 was used as neutral in a schematic, but I can't figure out why. Did they ground it? Did they just choose that as neutral while deciding X4/X2 would be their hot wire? Or is it because X4/X2 leads X3/X1? Please let me know and thank you in advance for the help

First off if you are feeding the primary with 480vac 3 phase and the transformer should be delta on the primary to Y secondary then you should have an XO terminal which you bond to a good earth ground. If thats so you won’t get but 208vac. A picture of the label on the transformer and what is the KVA ?. Is it a control transformer ?I I I need more info to help you out. It could be a delta to delta transformer.

 

[flee89]

First off if you are feeding the primary with 480vac 3 phase and the transformer should be delta on the primary to Y secondary then you should have an XO terminal which you bond to a good earth ground. If thats so you won’t get but 208vac. A picture of the label on the transformer and what is the KVA ?. Is it a control transformer ?I I I need more info to help you out. It could be a delta to delta transformer.

It's an Allen Bradley control transformer, single phase from what I understand. Part 1497B-A10-M14-3-N, 750VA. I attached the datasheet info from the transformer as well. A project I'm following used this and I was curious if it mattered which wire I used as hot or neutral or if I could use either.

 

[Megawatt]

It's an Allen Bradley control transformer, single phase from what I understand. Part 1497B-A10-M14-3-N, 750VA. I attached the datasheet info from the transformer as well. A project I'm following used this and I was curious if it mattered which wire I used as hot or neutral or if I could use either.

I’m getting old and my eyes are not as good as they use to be. Your picture is so blurry that I can’t read the wiring schematic. Please take another picture. @lucien is the man that could help you the most. I’m guessing that his eyes are better than mine.

 

[flee89]

I’m getting old and my eyes are not as good as they use to be. Your picture is so blurry that I can’t read the wiring schematic. Please take another picture. @lucien is the man that could help you the most. I’m guessing that his eyes are better than mine.

I'm so very sorry for that, I apologize! Here is an updated picture but it's still somewhat fuzzy because when I zoom in on the datasheet, it gets blurry. But I feel the information you people have given me is more than sufficient enough. I'm assuming choosing whichever output pair is fine because its just a single transformer as Lucien had mentioned. Thank you so very much for all of your help.

 

[Megawatt]

I'm so very sorry for that, I apologize! Here is an updated picture but it's still somewhat fuzzy because when I zoom in on the datasheet, it gets blurry. But I feel the information you people have given me is more than sufficient enough. I'm assuming choosing whichever output pair is fine because its just a single transformer as Lucien had mentioned. Thank you so very much for all of your help.

It looks like X3 and X2 go together which will be your neutral and X1 would be your 120vac. You must ground 2 and 3

 

[Lucien Nunes]

According to post #1 The OP is not using a 120-0-120 connection, but wants the two secondaries paralleled X1/X3 and X2/X4 to make a single 120V secondary of the full VA rating of the transformer. In that case he needs to choose which end of that paralleled pair of windings to tie to ground to create a grounded neutral. The only difference it makes is the relative phasing of the 480V and 120V circuits, i.e. whether the 120V hot wire goes positive when H1 goes positive or when H4 goes positive. Assuming the 480V is coming from a 480/277V service, both legs of the primary are hot and symmetrical to ground, so it does not matter which one the secondary is in-phase with.

If the 480V supply instead consisted of a 480V hot and a neutral,then there would be a preference to ground whichever end of the winding puts the secondary hot in phase with the primary hot. Also if there were multiple transformers serving the same 120V equipment it might be preferable to ensure their secondaries were all in phase with each other, to avoidn creating unexpected 240V potentials.

 

[Megawatt]

According to post #1 The OP is not using a 120-0-120 connection, but wants the two secondaries paralleled X1/X3 and X2/X4 to make a single 120V secondary of the full VA rating of the transformer. In that case he needs to choose which end of that paralleled pair of windings to tie to ground to create a grounded neutral. The only difference it makes is the relative phasing of the 480V and 120V circuits, i.e. whether the 120V hot wire goes positive when H1 goes positive or when H4 goes positive. Assuming the 480V is coming from a 480/277V service, both legs of the primary are hot and symmetrical to ground, so it does not matter which one the secondary is in-phase with.

If the 480V supply instead consisted of a 480V hot and a neutral,then there would be a preference to ground whichever end of the winding puts the secondary hot in phase with the primary hot. Also if there were multiple transformers serving the same 120V equipment it might be preferable to ensure their secondaries were all in phase with each other, to avoidn creating unexpected 240V potentials.

I guess I didn’t read the post correctly and thank you my friend.