Voltage too hot in shop...

[Jack Hovanec]

I’m not sure if anyone on here is good with the electrical side of things (i know I’m not). My shop is on an old wild leg delta system. I measure 250 phase to phase. I own a lot of euro machines that are rated for 220. Low and behold i just blew a transformer on my older sliding table saw due to what I’m assuming is the high voltage (unless it was a fluke). I called the power company out and the tech said that they only adjust if the voltage is out of their +/-10% tolerance from 240V. So they would tolerate up to 264V (wow).
I’m about to purchase a 230V wide belt sander and i would really not like to damage this machine. Does anyone have experience with this topic? Will a 230V machine tolerate this extra 20 volts? That would be right on the cusp of +10%.
Thanks in advance for any tips or recommendations.
Jack

[Rod Sheridan]

Equipment normally is designed for +/- 10% of rated.

Your 230 volt machine would be beyond rating at 250 volts.

If it were me I would use either an auto or a buck transformer to reduce the line voltage.....Rod

[Jim Becker]

Buck/boost transformer on the individual tools. I had to do that for my SCM/Minimax Slider because I was getting voltage too low to my shop from the street more often than was pleasant. They are pretty adaptable and you can set things up to match what your actual need is. Please note....I'm not three phase here, but the principle still applies I believe)

[Jack Hovanec]

Thanks for the replies. So i guess i would need to find a 250V primary to 220V secondary 3 phase buck transformer? Seems like a needle in a haystack kind of scenario. Or would 240 to 220 work the same?
Jack

[Dan Friedrichs]

"Autotransformer" (as Rod said). It has multiple taps so you just pick the one you want for the voltage you've got.

[Mike Cutler]

Jack

"220" is a "nominal" voltage value. You should be reading 230-240 across the service coming into the main breaker panel. I'm usually at ~ 238vac.
A higher voltage would actually be better than a lower voltage, as long as it's within reason. The lower the voltage, the higher the current, for a given load, and that increase in current is generally what is responsible for damaging motors.
Unless you have a NIST traceable, calibrated meter, it's kind of a guess as to exactly what the voltage actually is. The accuracy, or inaccuracy of your meter, could account for some of the error you're seeing.
Addy Protocol
I've been calibrating the instrumentation that monitors the electrical grid voltage in the north east, and frequency for 30+ years. Month in and month out.
I think you're probably fine.

[David Kumm]

When you refer to wild leg delta, do you have one leg that reads 208 to ground as in a three phase 240 delta arrangement? If that is the case, the 208 leg should not feed the transformer in your machine. Even though it reads 240+ pole to pole with any other leg, I've had small machine transformers muck up so I avoid that leg on anything but the motor. Dave

[Art Mann]

240VAC has been the standard across the USA for at least 40 years. 220 is just an unfortunate name holdover from days long gone. So is 110. If you buy just about any new equipment, it is designed to work at 240 +/- 10%.

[Rod Sheridan]

240VAC has been the standard across the USA for at least 40 years. 220 is just an unfortunate name holdover from days long gone. So is 110. If you buy just about any new equipment, it is designed to work at 240 +/- 10%.

Hi Art, the OP has European machinery, the older machines were designed for the 220/380 volt 3 phase system, modern European machines are designed for 230/400 Volts.

In this case his machinery is actually designed for 220 volts...................Regards, Rod.

[Bert McMahan]

Search "Transformer" on McMaster-Carr and fill out the info you need. I don't know what kind of power draw your system needs, but (if I read this table right), item number 70525K75 will do it. It can do 245V to 222V at 5,000 Va which should cover a 5 Hp motor.* It's $134.

*I am not an electrician, please verify these numbers :D It APPEARS that it's a 1:1.1 transformer, so at 250 V in you should see 226 V out.

[Osvaldo Cristo]

I’m not sure if anyone on here is good with the electrical side of things (i know I’m not). My shop is on an old wild leg delta system. I measure 250 phase to phase. I own a lot of euro machines that are rated for 220. Low and behold i just blew a transformer on my older sliding table saw due to what I’m assuming is the high voltage (unless it was a fluke). I called the power company out and the tech said that they only adjust if the voltage is out of their +/-10% tolerance from 240V. So they would tolerate up to 264V (wow).
I’m about to purchase a 230V wide belt sander and i would really not like to damage this machine. Does anyone have experience with this topic? Will a 230V machine tolerate this extra 20 volts? That would be right on the cusp of +10%.
Thanks in advance for any tips or recommendations.
Jack

Please do not take me wrong but 10% tolerance looks me too high. Unfortunately ANSI site requires money to download the specific norm (it looks odd) but most of Europe and Brazil specify 5% tolerance for domestic mains.

Anyway electric motors are usually specified to support much higher variation. Again, according to Brazilian norms motors must have 15% tolerance in the voltage input - I don't think it will lower in the US.

Electronic stuff usually are at 10% minimum tolerance.

[Art Mann]

I tend to forget that this forum in international!


Hi Art, the OP has European machinery, the older machines were designed for the 220/380 volt 3 phase system, modern European machines are designed for 230/400 Volts.

In this case his machinery is actually designed for 220 volts...................Regards, Rod.

[Rod Sheridan]

I tend to forget that this forum in international!

LOL.................Yup, there are a lot of us "foreigners" on here.:D

I was working in Virginia a week ago and really enjoyed the weather there, much nicer than at home......Rod.