Transformer Question

[Little Bill]

Can this transformer be wired both ways? As in reversing the primary & secondary connections, either making it a step up or step down transformer?

https://www.usesi.com/federal-pacifi...y-1-kva-507299

 

[Hv&Lv]

Can this transformer be wired both ways? As in reversing the primary & secondary connections, either making it a step up or step down transformer?

https://www.usesi.com/federal-pacifi...y-1-kva-507299

Yes, but you have to take some considerations into account. Taps work backwards, energizing currents may be higher etc
it would also be nice to see the schematic of that unit.

 

[Little Bill]

https://www.swgr.com/store/Dry-Type-Low-Transformer/product/11-9619.aspx

Yes, but you have to take some considerations into account. Taps work backwards, energizing currents may be higher etc
it would also be nice to see the schematic of that unit.

See if this helps
https://www.swgr.com/store/Dry-Type-Low-Transformer/product/11-9619.aspx

 

[Dennis Alwon]

Personally if the transformer info does not state that you can step up or down then why do it. I doubt it would be compliant based on the listing.

 

[Little Bill]

Personally if the transformer info does not state that you can step up or down then why do it. I doubt it would be compliant based on the listing.

I don't even know the use for the tranny. Just got a text from a friend with pics of the tranny. I was just wondering if it could be reversed. I'm sure they will ask since they asked me to call, which I haven't yet.

 

[MTW]

1

 

[Little Bill]

Well, I came to the wrong conclusion in assuming they would ask if it could be reverse wired. That's usually the type thing they would ask but not this time. They only wanted to know if it would work for 277V stepped down to 120V. The wiring diagram confused them. I told them how to wire for 120V secondary. But what I didn't tell them was the OCPD. The load is only LED lighting so I think a 15A OCPD would suffice, is that correct? Also, would just the primary need OCPD or would both it and the secondary need it?

 

[iceworm]

This thread got me looking at Table 450.3.B, for small transformers. This transformer in question is a good example:

277V/120V, 1KVA
primary 3.6A
Secondary 8.3A​

Primary only protection, currents less than 9A, Maximum rating is 167% x 3.6 = 6A No provision for Next Size Up

Primary and Secondary Protection,

Primary Maximum rating is 250% x 3.6 = 9A.
Secondary, currents less than 9A, 167% x 8.3 = 13.9A.
Again, no provision for NSU.​

I am baffled for a couple of reasons;
1. How come I never noticed this before? :?:dunce: I checked back three cycles - no change. I don't recall ever working a small transformer before - unless it was in a control panel. I would have used primary and secondary fuse for that .

2. So what are they telling us - Use fuses? That doesn't seem reasonable.

So why don't I use 240.4.B, NSU for CBs 800A or less. T450.3.B has provision for NSU for currents 9A or more. So, I thinking they would have included the NSU if they thought it was necessary.

Anybody got any clues where I am missing the point?

Color me a confused

worm