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Mike, Master Electrician
Category: Electrical
Satisfied Customers: 1425
Experience:  Licensed Master Electrician - OnQ Certified Data Voice Audio Video Installer
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Please verify via this cutsheet, figure J on the last page

Customer Question

please verify via this cutsheet, figure J on the last page single phase is my input?
what is my output?seems like H4 and X1 are my inputwire nut x2 and x3H4+H2 & H1+X4 are my outputs?is this correct?
Submitted: 1 year ago.
Category: Electrical
Expert:  ProGrade replied 1 year ago.

That is correct which puts both input & output on H4, et al. Let me know if you have any questions

Customer: replied 1 year ago.
this seems crazy to me, why does it take it through h2? thats how its draining the volts from that leg?
Expert:  ProGrade replied 1 year ago.

Those are the characteristics of a buck-boost transformer. What are you trying to do, increase the voltage? From what to what?

Customer: replied 1 year ago.
i have the t137921chart says use fig J for 277, the closest to my 252v yes i have 252 coming inthen trying to step down to 208vwith ability to pull 30.3 amps max draw ever 20a continuous
Expert:  ProGrade replied 1 year ago.

10-4, thanks, looking at the data, will return

Expert:  ProGrade replied 1 year ago.

You are attempting to use a buck-boost transformer where a step-down transformer should be used instead. Does the load specifically require 208 Volts or will it run on 230?

If you have 252 volts, that is within specs for a 230 Volt system (230 x 1.10 = 253)

However, if this is on a 480/277 Volt System, you still need a step-down transformer, not a buck-boost.

Customer: replied 1 year ago.
boy oh boy lol,i trust you on this for sure, and makes me nuts because I do, and acme tech support told me to use this, the place I got it from also called acme and was told the same thing, that they recommend i use this t137921 to 40a or t137922 to i said send it.but before this, they sent me wrong one already, but it was a step down isolation, i wired it right, metered it out, 212v, hooked oven up and it ran perfect for about 2 minutes.once the max draw kicked in and it really started the warming cycle, pulling 30.3a max, it smoked like a rocket
1st one could only handly 8a LOL, when i told them 30.3a at start 2nd try here with this different buck boost
sarcastic: i told them again 252v to 208v 30.3max 20 continiously
so they said use this one, and supposedly he was doing the math and discussing 3 or 4 different ones and reccomended this oneso now im nervous again, it better not blow any heating elements this platt will be buying them not you know how to check the math on this buck boost? 252v in 208 or closest to it out need 30a max 20 continiouslydoesnt the cut sheet give us what is needed to calculate the exact drop in V and respective available A your opionion, this will work right? even though maybe its not what you would have sold to someone? it gets the job done at least?
Customer: replied 1 year ago.
man i cant believe you left me hanging like this i needed this answer , in a few hours the acme tech support will be open but I used this to get the answers faster
Expert:  ProGrade replied 1 year ago.

Because you are trying to use it in a manner that it is not intended or designed for, see above