Need help with Acme buck boost transformer

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RyMac

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I have an Acme buck boost transformer (A3030K0310B) to go from 240v 3 phase to 208v 3 phase. I've tried the three different wiring options and don't seem to be getting the correct voltage on the output.
Also is it safe to assume the transformer itself doesn't require a neutral? I see nowhere to connect one
 
OK.
The unit makes it possible to generate a bucked 208 delta OR wye from a nominal 240 correspondingly delta OR wye.
It does not need a neutral to operate properly. If delta there is no neutral on either side. If wye the primary neutral is also the secondary neutral but with no connection to the transformer.
The wye point of the transformer is virtual, just as it would be for a wye to delta isolation transformer.
It is unusual to call it buck/boost autotransformer with all of the taps on one side of the output, but the fact that there is a step down ratio on all three taps makes it work.
Its behavior if the input single phases will be interesting, especially with respect to the neutral, but probably not hazardous.
No help in figuring out why it does not work for you though....

mobile
 
RyMac said:
I have an Acme buck boost transformer (A3030K0310B) to go from 240v 3 phase to 208v 3 phase. I've tried the three different wiring options and don't seem to be getting the correct voltage on the output.
Also is it safe to assume the transformer itself doesn't require a neutral? I see nowhere to connect one
Click to expand...
What output are you getting?
 
RyMac said:
I have an Acme buck boost transformer (A3030K0310B) to go from 240v 3 phase to 208v 3 phase. I've tried the three different wiring options and don't seem to be getting the correct voltage on the output.
Also is it safe to assume the transformer itself doesn't require a neutral? I see nowhere to connect one
Click to expand...

Input on H4, H5, H6
Output on X1, X2, X3

should work.
 
You guys understand transformers far better than I ever will but it seems like you would still have a secondary to neutral voltage problem.
 
RyMac said:
I have an Acme buck boost transformer (A3030K0310B) to go from 240v 3 phase to 208v 3 phase. I've tried the three different wiring options and don't seem to be getting the correct voltage on the output.
Also is it safe to assume the transformer itself doesn't require a neutral? I see nowhere to connect one
Click to expand...

augie47 said:
You guys understand transformers far better than I ever will but it seems like you would still have a secondary to neutral voltage problem.
Click to expand...
A little help is required of the op'er to proceed. The transformer series brochure linked to earlier shows no neutral connection... seemingly indicating the transformers are for 3Ø 3W (wire) only loads. The OP'er implies he needs one. We're left at a undeterminable nexus until he provides additional information.
 
One important word of caution. The wiring diagram for the buck/boost configuration MUST BE FOLLOWED as when connected incorrectly very dangerous and extremely high voltages can be generated. In other words, don't experiment.
Buck boost configuration required wiring the HV and LV windings in a series parallel configuration which is show on the wiring diagram in question. The load is in series with one winding and the voltage as is either bucked or boosted in that winding with the second winding.
Should the transformer be configured incorrectly and extremely high voltage on the other windings is the result.
OCP as included in NEC art 450 is extremely important it follow.
When I look at the wiring diagram if it is followed it will work. However, it will not make sense to those how are expecting to wire a transformer in a conventional fashion. I messed with your mind.
Simply follow the wiring diagram exactly.
Incidentally, the OP still has not responded with what voltage he is getting.
 
RyMac said:
I have an Acme buck boost transformer (A3030K0310B) to go from 240v 3 phase to 208v 3 phase. I've tried the three different wiring options and don't seem to be getting the correct voltage on the output.
Also is it safe to assume the transformer itself doesn't require a neutral? I see nowhere to connect one
Click to expand...

By it's very nature, a buck-boost transformer is an autotransformer, so it is used when isolation is NOT needed and in this case, it is intended for boosting or bucking 3 phase loads. If you needed 208Y120 on the secondary, you would used a 240D to 208Y isolation transformer set up as a separately derived system and ground the neutral on the secondary. Your question was where to connect the neutral on this transformer so the answer would be, you don't. Whether or not you need it is a question not addressed, but if you did, you bought the wrong transformer.

So, back to the question asked of you earlier regarding you not getting the right voltage; how did you connect it and what did you get?
 
Studying the schematics very closely in a quiet room typically does the trick. Talking you through this over the forum is problematic at best.

wile-e-coyote-acme-products-catalog.jpg
 
but, using your analogy, following our advice can have more interesting results:
wilecoyote.jpg
 
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