Buck Boost Transformer

Steve@Advance

Well-known Member
Just installed a "buck boost transformer", first
time I ever dealt with one. It worked! Or so far,
I'm getting the right voltage, haven't run it
with a load though.

I know the theory behind a transformer, but this
is just some really weird circuitry. I know it's
all math, but I just can't wrap my mind around
what's happening in there! Bought them from my
local electrical salvage supplier. He dug them
out of the bone pile, showed me an application
chart and a wiring diagram. Told me "Don't over
think this, just do it and it will work!"

We just bought a new CNC band saw. It has an
inverter drive, and the recommended voltage was
208 to 240 volt. The voltage in the shop runs
high, around 249 to 251. They (the dealer) didn't
want to start it up with that high voltage, but I
talked them into it, everything else in the shop
has run just fine for years, including another
one of their saws with the same drive.

Well, three days later the inverter drive failed.
Of coarse they blamed the high voltage, agreed to
warranty it but we had to get the voltage down.

So, stepping out in faith, wired them up to the saw, got the
volts down from 250v to 226v, just like the chart
said it would!

Wondering though, does anyone else have above
average voltage in their shop? Have any problems
with it? The electric company says it's normal,
they won't do anything about it... Electricians
I've talked to say don't worry about it...

New equipment dealers don't like it. Want to see
it within their specs for warranty purposes...
 
Old school electrical guys will tell you that is ok but 260 volts is to high. In today's world of vfd's the circuits won't hold up vs old school stuff that used NEMA magnetic starters, with pot switches. The vfd plays with hertz (cycle rates) to control speed. I've sold tons of vfd's and if it's not perfect conditions and or sized wrong, must company's will put up a stink. Stuff today is plastic and heat kills them
 
Buck and boost seem to scare many people. They're really pretty simple to figure. They commonly come in 2 ratios 16/32 and 12/24 and quite a few sizes. The ratios are expressed as voltagew and the size is simply the difference (in KVA)that the new difference covers proportionately. If it's three phase it will be best in open delta (two transformers). They are basically auto transformers and are wired accordingly.

I have installed many and they work well even under varying loads. Much better than having over or under voltage on most equipment.
 
The manufacturer we rep for used buck-boost transformers in their machines for many years. The control circuits ran much better at 240 than 208 so they installed a buck-boost and a selector switch to raise the control circuit voltage to 240 in 208 VAC applications. Switch selected buck -boost when set to 208 and bypassed the xfmr when set to 240.
 
Steve, It all has to do with E&M, Electricity and Magnetism. The class most students hated, present company included. Part of the transformer can be wired in such a way the alternating magnetic fields can either aid or oppose, increasing or decreasing the voltage.

About a year ago I ran into my first Buck Booster transformer, yes weird.
 
Nothing exotic about it. It's just an autotransformer. A Variac is an autotransformer as well, just one with a nearly infinite number of taps.

I find it interesting they use the term "buck boost". There's a quite different DC device also called a buck boost that uses a coil to step up DC voltage. It's the basic circuit used in switching power supplies.
 
Interesting, I've never seen a coil DC buck booster. A year ago, I've never seen an AC buck booster either.
 
Tell the power company they are full of horse poop!! Tell them to change the tap on the transformer!!!
 
For a few years I ran a service truck for an electrical contractor.
Once in a while a customer would have a low voltage problem. I'd call the utility and they would put a recording meter on for 24 hours, it would be inclosed and one could not see it's readings, and the utility would say that everything was OK. So what I would do is put ours on when the utility's was on so they would see our meter. Things always got fixed then.

Dusty
 

We sell tractor parts! We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today.

Back
Top