buck boost transformer

[hhsting]

I have primary three phase 208V secondary 480/277V three phase 30 kva.

Question:

1. Does this type of transformer need secondary protection? If yes then what size?

2. Would this be considered SDS requiring GEC to grounding electrode or non SDS Not requiring GEC to grounding electrode?

 

[winnie]

Can you provide a picture of the nameplate? You say 'buck boost' transformer, which implies an 'autotransformeer' configuration; but the voltages you describe would much more commonly be a 'wye:delta isolation transformer'. The answers will be different depending upon which it is.

1) a 480/277V secondary is not one of the types permitted to use primary protection to protect the secondary. However in an autotransformer it might arguably be a set of 3 single voltage two wire transformers?

2) An autotransformer is not an SDS. An isolation transformer is an SDS.

-Jon

 

[hhsting]

Can you provide a picture of the nameplate? You say 'buck boost' transformer, which implies an 'autotransformeer' configuration; but the voltages you describe would much more commonly be a 'wye:delta isolation transformer'. The answers will be different depending upon which it is.

1) a 480/277V secondary is not one of the types permitted to use primary protection to protect the secondary. However in an autotransformer it might arguably be a set of 3 single voltage two wire transformers?

2) An autotransformer is not an SDS. An isolation transformer is an SDS.

-Jon

Below are the links to the transformer according to plans is buck boost that has the datasheet, configuration and manufacturer model type T3030K0023B Acme. Can anyone assist post #1 question:


Link #1: https://www.hubbell.com/acmeelectri...mer/T3030K0023B/p/1655501#prod-detail-section

Link #2: https://hubbellcdn.com/specsheet/T3030K0023B.pdf

Link #3: https://hubbellcdn.com/technicaldrawing/T3030K0023B.pdf

 

[ptonsparky]

Below are the links to the transformer according to plans is buck boost that has the datasheet, configuration and manufacturer model type T3030K0023B Acme. Can anyone assist post #1 question:


Link #1: https://www.hubbell.com/acmeelectri...mer/T3030K0023B/p/1655501#prod-detail-section

Link #2: https://hubbellcdn.com/specsheet/T3030K0023B.pdf

Link #3: https://hubbellcdn.com/technicaldrawing/T3030K0023B.pdf

I don’t see that as a buck/boost. It standard step down from 480 to 240 delta with a high leg. Look at your link #3.

Fuse it as you would any three phase transformer. 60 & 100 would be my thoughts.

 

[roger]

I don’t see that as a buck/boost. It standard step down from 480 to 240 delta with a high leg. Look at your link #3.

Fuse it as you would any three phase transformer. 60 & 100 would be my thoughts.

Agreed, that is a standard transformer not a buck / boost.

Roger

 

[winnie]

Below are the links to the transformer according to plans is buck boost that has the datasheet, configuration and manufacturer model type T3030K0023B Acme. Can anyone assist post #1 question:

The part number and the links don't match your original description at all.

I have primary three phase 208V secondary 480/277V three phase 30 kva.

The T3030K0023B is a 480V primary to 240V secondary delta:delta isolation transformer. It is not a 'buck-boost', is not a 'step up', and is not useable for 208V.

So any answers for this transformer are likely not quite correct for whatever situation you will be installing it.

-Jon

 

[augie47]

(If this was a 1st time post I'd be checking profiles to see if it was a DIY)
As noted by everyone above, this is not a buck & boost but a standard power transformer.
Look at 450.3 for overcurrent protection requirements and 250.30 for grounding.

 

[ptonsparky]

OP has touched on this subject more than once. Time to get the books out and study a bit.

 

[roger]

Since the OP knows this is not a buck/boost transformer now we will close this thread.

Roger