480/400vac transformer question

knucklebucket

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Join Date
Feb 2013
Location
Greeneville, Tennessee
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hope this isn't out of line, but only forum I belong to where I might get the answers I'm looking for. My company bought a pleater from a company and it turns out it is european. so had to also buy a 480vac/400vac transformer. I have it hooked up but with no success. factory installation on machine, I have 5 wires, 2 black,1 brown, white (neutral) and a ground. from the transformer I have 3 black and a ground. I have the 3 black tied to 2 black and brown and the ground is grounded. I do not have a white neutral on secondary side of transformer. I read voltages on two of the three phases, and zilch on the 3rd phase. Obviously I'm doing something wrong, but this totally something I'm not used to. anyone whom can chime in it would be greatly appreciated.
 
First off, reducing the voltage from 480V to 400V is not going to fix the problems with motors and anything depending upon the frequency. Motors labeled for 400V 50hz will not run properly on 400V 60hz which is what you will get from a transformer.

Fortunately, VFD's can live with the reduced voltage even at 60hz and possibly some resistive heating equipment will be ok too. But motors are not going to be happy if the are across the line thru magnetic starters.

The basic problem is that motors run on the volts/frequency ratio so a 480V 60hz motor has a ratio of 8/1. So does a 400V 50hz motor (400/50 = 8) Changing one without changing the other is going to make the motors run hot or not develop normal torque.
 
i dont think the transformer is wired correctly.
although DickDV is also correct.
can you post a photo of the connections / wire layout.
this could be Delta/Star or Star/Star wiring.
Is your mains voltage 480 or 400 V 3 Phase?
which way should the transformer be connected?
 
Is your mains voltage 480 or 400 V 3 Phase?
Click to expand...
In the US, our common, standard voltage for Motor Control Centers is 480 volts phase-to-phase, 3-phase, 60 Hz, with 277 volts phase-to-neutral (if a neutral is available). In most MCCs, neutrals are not installed or used.
 
if the machine ie european, the frequency of the solenoids and starters is probably 50 hz.

if that's the case, these devices will typically run 3 months before they start to fail. a customer of mine learned that the hard way.

please check the devices and make plans accordingly if they are 50 hz.

regards,
james
 
Most motors have dual frequency ratings. It is necessary to check the details

Thanks for the info Lancie1 - nice to know

As far as 5 wire transformer - this can not be correct even if it is wired Vee/delta
I would suggest it is a single phase transformer
Also
Most three phase step down transformers have multiple trappings in the primary or secondary so the voltage can be trimmed.
What is the VA or KVA rating of this transformer
 
I would suggest it is a single phase transformer
Click to expand...
I would second that. At this point, I would be looking for some definite information about the actual required voltage level. I would copy the transformer nameplate, paying attention to the number of phases, and the available secondary voltage levels, and compare to the nameplate voltage of the machine motors.
 
What country is the machine from? It sounds like what you have may be a single phase machine with a secondary voltage input.It also sounds like the phase you read no voltage on is actually ground, look at the wire again and see if that brown is a dirty white.but I'm just guessing until you can tell us what the machine name plate says, what the transformer name plate says, and where the machine came from.
 
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Sounds like it could be the wrong Transformer. Without a Picture I am Just guessing. You need a dual htz Transformer made for the 400V European Machine. Most newer European machines need the Neutral (Blue) to work correctly. If it is 3 phase it should be labeled on the Transformer 480 480 480 and gnd incoming and 400 400 400 Neu and ground outgoing. The right transformer should be both 50/60 htz hopefully no damage was done some need the neutral some do not but most newer do.. A picture or information of the machine connections would help to determine what is correct.



"If you are operating in the United States, you will most likely be operating on 60hz. Our Euro Standard Transformers can come rated for 50hz or 60Hz with many larger ones dual rated 50/ 60Hz, while our Euro Plus transformers operate on 60hz exclusively."
http://www.temcoindustrialpower.com/product_selection.html?p=euro-selection-guide#480_standard
 
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