208V Incoming Power to 240VAC, 60A Machine

Status
Not open for further replies.
G

Guest19369

Member
Location
Columbia, SC, USA
I have 208V in the building and need to set up a machine (Single Phase) that has incoming power needs of 240VAC, 60A. I believe that I will need a transformer for this and would like some help figuring out what kind. Please assist. Thanks
 
augie47

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired)
does the machine require 1 phase 240 or 240/120 (is a neutral involved) ?
 
Dennis Alwon

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
Not sure what you mean by what kind of transformer. Since you have 60 amps you need about a 15kva transformer. 60 * 240v = 14,400 or 14.4kva
 
Saturn_Europa

Saturn_Europa

Senior Member
Location
Fishing Industry
Occupation
Electrician Limited License NC
Guest19369 said:
I have 208V in the building and need to set up a machine (Single Phase) that has incoming power needs of 240VAC, 60A. I believe that I will need a transformer for this and would like some help figuring out what kind. Please assist. Thanks
Click to expand...

What type of machine is it?

Many motors are dual voltage rated.

Do you have a picture of the name plate?
 
augie47

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired)
:) You have opened pandora's box releasing the bloviators,,, I would suggest you check the link provided or any transformer supplier for "buck n boost" and get the info you desire straight from the horses mouth
(I believe you will end up with a 2kva bnb)
 
Last edited by a moderator:
iwire

iwire

Moderator
Staff member
Location
Massachusetts
Guest19369 said:
But does the kVA still have to meet the same 240V x 60A = 14,400 kVA calculations or can you use a lower kVA?
Click to expand...

Much much lower, that is why I use the online or catalog sizing resources.

Using buck boost also simplifies the installation as you will not need a grounding electrode run to it as you would with a standard 208 to 240 transformer.
 
Jraef

Jraef

Moderator, OTD
Staff member
Location
San Francisco Bay Area, CA, USA
Occupation
Electrical Engineer
Before spending time and money needlessly, I would do a deep-dive investigation of the machine to determine if the 240V is as critical as you think it is. A LOT of single phase 240V motors are perfectly fine with 208V, because the motor mfrs KNOW that a lot of commercial applications fed from 3 phase systems will be 208V, not 240V. Most electronic power supplies for computerized systems or solid state controls now have very wide input voltage tolerances, for example 110-250V input with no external transformer required. And if it is something like a resistive heating element, the 208V may mean it will not get as hot, but that may only mean whatever it does will just take a few seconds longer. Bottom line, 208V may not be a problem you need to fix.
 
ActionDave

ActionDave

Chief Moderator
Staff member
Location
Durango, CO, 10 h 20 min from the winged horses.
Occupation
Licensed Electrician
Jraef said:
Before spending time and money needlessly, I would do a deep-dive investigation of the machine to determine if the 240V is as critical as you think it is. A LOT of single phase 240V motors are perfectly fine with 208V, because the motor mfrs KNOW that a lot of commercial applications fed from 3 phase systems will be 208V, not 240V. Most electronic power supplies for computerized systems or solid state controls now have very wide input voltage tolerances..
Click to expand...
I agree.
 
kwired

kwired

Electron manager
Location
NE Nebraska
I also agree with making sure your equipment can operate directly from 208 volts. Many motors will be fine. Heating elements - just don't get quite as hot, but unless that impacts overall performance often isn't a big deal.

If you do need to boost voltage - your kVA rating of a buck/boost is only on the difference between the two voltages.

If you actually have a 60 amp load @ 240 volts then as mentioned it is 14400 VA. An isolation transformer would need to have at least 14400 VA rating. But if boosting from 208 to 240 (a difference of 32 volts), your buck boost transformer only needs a 32 volt x 60 amp = 1920 VA rating.

If you equipment requires a 60 amp circuit - the actual load is likely less and you may even be able to go with a smaller transformer.
 
iwire

iwire

Moderator
Staff member
Location
Massachusetts
Jraef said:
Before spending time and money needlessly, I would do a deep-dive investigation of the machine to determine if the 240V is as critical as you think it is.
Click to expand...

It is worth a check but for whatever reason I run into and it comes up on this forum that some manufactures get real particular about the supply voltage.

I have had 7-11 Slush drink machines that had very tight voltage specs and threats of taking my first born if the requirements where not met.

2.jpg


People are always asking about this issue with tanning beds, they seem to require specific supply voltages.

Most common for me is motors, specifically refrigeration compressor motors on tractor trailer units. If we run them on 208 they will often trip out the overload, apparently in shipping yards they use 230 delta to supply these units but when they show up at the stores we work at we have 208 available .


Besides that, in the end I make my living installing electrical equipment, talking someone out of a buck boost is counter productive. :cool:
 
kwired

kwired

Electron manager
Location
NE Nebraska
I haven't run into much equipment that can't run on 208 vs 240 or vice versa. Most of the time the issue from the dealer/vendor of such equipment is they will not honor warranty if not supplied with the voltage they ask for. There is a lot of equipment that is marked to operate at either voltage. Occasionally you may need to change a tap on a control transformer or something of that nature, to install it correctly. I have seen many HVAC units installed on 208 systems with control transformer tap on the factory 240 setting that run fine for years.
 
augie47

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired)
kwired said:
I haven't run into much equipment that can't run on 208 vs 240 or vice versa. Most of the time the issue from the dealer/vendor of such equipment is they will not honor warranty if not supplied with the voltage they ask for. There is a lot of equipment that is marked to operate at either voltage. Occasionally you may need to change a tap on a control transformer or something of that nature, to install it correctly. I have seen many HVAC units installed on 208 systems with control transformer tap on the factory 240 setting that run fine for years.
Click to expand...

There, problem is solved ! Pay no attention to the voltage and in the event something goes wrong tell the customer kwired advised it would be o.k. and send an associated repair bills to him :D
 
Status
Not open for further replies.
Top