Please help out with this.

We have an discusssion here and the opinions are not the same.

On a transformer label I read

PRI 361-370, 5-380-389, 5-399 (DElTA)
SEC 190 (STAR) + N

Please help me interpret the voltages on the Pri

Thanks a lot for your comments.

John

 

So, tell us, what does the discussion group think? Then we will tell you who is more correct!

If your hooking up transformers and don't know how to read or interpet the primary wiring you should leave well enough alone.

 

Responding to John's Tue, Aug 3, 9:57pm query:

What is country of origin? In the interim, it appears to describe a 3-phase transformer. The primary-winding is delta connected. The nominal phase-to-phase input rating is 361 to 370 Volts, with two +5% tap settings.

The secondary-winding is star (or wye) connected. The nominal phase-to-phase output rating is 190 Volts. N means that the neutral point is brought to an external terminal! Note: If secondary ph-to-ph is 190, then the phase-to-neutral rating is 190 / sqrt(3) Volts.

Regards,
Phil Corso, PE {Boca Raton, FL, USA}
[[email protected]] ([email protected])

 

It looks like the primary is rated 361 to 370 Volts. It also has two 5% taps. The middle tap is for a supply of 380 to 389 V. The top tap is rated at 399V. Use the tap that corresponds to the plant voltage.

 

Hi John,

FIRST: Who made the transformer. IF POSSIBLE!!

SECOND: What type of machine, system, computer, etc... is it used in & what does it do in it's functions as an end result of it's process.

THIRD: By the PRIMARY'S stated input voltage, (361-370), this is based on 60 Hertz. Where it states (5-380-389), "THEY" are taking it for granted that you know it means, 50 Hertz. As for the last part (5-399), there are "connections provided" so that if your power input is constant, you make your connections there.

FOURTH: ALL PRIMARY CONNECTIONS ARE FROM A "DELTA (NOT "DElTA) TYPE OF CONFIGURATION"!!!

FIFTH: IF, the input is correct, the secondary output of the transformer will be 190 VAC in a "STAR TYPE OF CONFIGURATION"!!!"

SIXTH: The difference between a DELTA & a STAR is: DELTA is a triangle with the power from the "points". The GROUND is a "TRUE GROUND/NETURAL, (PER N.E.C. CODE)"!! The STAR is like a "Y" with the power coming off the ends of the Y & the center of the Y is a "TRUE GROUND/NETURAL, (PER N.E.C. CODE)"!!

SEVENTH: The only way you can mix DELTAs & STARs is thru transformers to the best of my knowledge.

Hope this helps!!!