Any assistance with buck boost transformer?

[_strickland]

I fully realize most people here would say just hire an electrician and I'm willing to do that if no one feels comfortable providing input.

I need to install a buck-boost transformer for my ac condenser because the incoming voltage from my electric company is too high, usually hovers around 250-251V. Using the buck-boost I can take it down to 234. I know the H wires are for the line voltage, the X wires are for the low voltage to buck down. I've also identified the wiring diagram I need to follow to accomplish what I'm trying to do, but I admittedly don't read wiring diagrams well at all. Could anyone give me a step-by-step of which wires to tie together?

 

[mike93lx]

Why do you think 250v is too high?

 

[sparky 1971]

250 volts isn't too high. As long as it's within 5% of nominal (240) it's fine. 240 + (240 X .05) = 252.

 

[mm08822]

250v is close to the upper limit. I wouldn't go out and buy a b-b xfmr b/c of that.
Here is a snip-it from a condenser unit spec:


If I had a b-b xfmr sitting around, I might install it - but not my 1st priority. You would also need it sized (KVA rating) for the load.

A downside to having a b-b installed is, if the voltage sags in your area, then the b-b could compound that problem.

I have seen the voltage at my house as high as 254V and I'm running the same condenser for years.

 

[Chuckster in NJ]

Call the utility company and have them look into this "issue"……… I would avoid using a BB transformer.

BTW! Be thankful you don't have low voltage.

 

[mike93lx]

Call the utility company and have them look into this "issue"……… I would avoid using a BB transformer.

BTW! Be thankful you don't have low voltage.

I'm guessing you know this, but for the OP they won't do anything since it is in an acceptable range.

 

[_strickland]

Thanks everyone for the replies. My main reason for asking about it was that my condenser is a variable speed, and the drive systems on them are the most sensitive to too much, or too little voltage. It's often one of the main reasons why variable units fail.

 

[mike93lx]

What is the spec on the unit?

Why would you want to drop it down to 234 specifically?

 

[_strickland]

The spec on the unit is the same as any other, 208/230. Most all bb are either 12/24 or 16/32, and dropping 16 would get me the closest to 230.

 

[mike93lx]

The spec on the unit is the same as any other, 208/230. Most all bb are either 12/24 or 16/32, and dropping 16 would get me the closest to 230.

I should have been more specific.
What is the upper limit if the units operating range? 208/230 doesn't really tell us anything especially since 230v isn't a thing in single phase service in the US

 

[_strickland]

I should have been more specific.
What is the upper limit if the units operating range? 208/230 doesn't really tell us anything especially since 230v isn't a thing in single phase service in the US

The service manual says 253. I have observed the incoming voltage getting that high a couple times before.

 

[wyliesdiesels]

I fully realize most people here would say just hire an electrician and I'm willing to do that if no one feels comfortable providing input.

I need to install a buck-boost transformer for my ac condenser because the incoming voltage from my electric company is too high, usually hovers around 250-251V. Using the buck-boost I can take it down to 234. I know the H wires are for the line voltage, the X wires are for the low voltage to buck down. I've also identified the wiring diagram I need to follow to accomplish what I'm trying to do, but I admittedly don't read wiring diagrams well at all. Could anyone give me a step-by-step of which wires to tie together?

wiring a buck-boost is easy

per your diagram, line input 1 goes to H1 as well as 1 leg of the output

Line input 2 goes to X2/X4 spliced together.

then you splice X1 to X3, H4 & the other output leg

next splice H2 & H3

But i would call your PoCo first and let them know the voltage is running a bit high. See what they say. could be a distro regulation issue

 

[wyliesdiesels]

I should have been more specific.
What is the upper limit if the units operating range? 208/230 doesn't really tell us anything especially since 230v isn't a thing in single phase service in the US

all motors are rated 115v/200v/230v/460v for system voltages of 120/208/240/480v

 

[wyliesdiesels]

The service manual says 253. I have observed the incoming voltage getting that high a couple times before.

thats higher than 5% so i would call the PoCo

 

[alfredeneuman]

all motors are rated 110v/200v/230v/460v for system voltages of 120/208/240/480v

For 120V use the motors are rated for 115V

 

[sparky 1971]

The service manual says 253. I have observed the incoming voltage getting that high a couple times before.

How often do you check the voltage? I have checked mine a grand total of one time, and that was only because I put a new service in and before I turned the main on, wanted to make sure I didn't do anything stupid. I couldn't even tell you what that voltage was.

 

[Chuckster in NJ]

Best advice is to read my post #5…….. You pay big bucks to the utility so call them and they will most likely come out for free to "investigate" the potential problem.


BTW! Hopefully the OP used an accurate meter and checked the accuracy with a second meter.

 

[wyliesdiesels]

For 120V use the motors are rated for 115V

yeah whoops, typo

 

[wyliesdiesels]

Call the utility company and have them look into this "issue"……… I would avoid using a BB transformer.

BTW! Be thankful you don't have low voltage.

yup

had a trouble call years ago where appliances were tripping breakers.

After arriving and discussing the issue with the homeowner, I discovered the voltage to the mobile home main service panel was 228v with no load. when the microwave or AC turned on the voltage dropped even lower which caused them to draw more power than usual. The microwave breaker ended up tripping. If i ran the oven, the voltage drop was even worse.

I explained what was going on and the homeowner told me that Profit Gouge & Execute (PG&E) had been out there for months trying to fix power issues in the park. At one point they had to replace equipment and while doing so ran the entire park off of generators. I explained to her that it looks like the problems werent resolved and she needed to reach out to the electric provider & let them know there are still issues. no clue what happened after that....

 

[mike93lx]

all motors are rated 115v/200v/230v/460v for system voltages of 120/208/240/480v

Yeah, I get that. I was looking for a specified range of acceptable voltages

 

[alfredeneuman]

NEMA uses a different criteria for motors to determine voltage limits than general circuits.
It can be +/- 10% without causing immediate damage to the motor, but caution that running it continuously at the voltage will shorten the life of the motor.