transformer identification

[eminem]

I am a student at a local trade school and I need some help!!! My dilema begins with an instructor who gets a kick out of making us rack our brains to find answers to his trick questions at the end of each week. This week he would like to know why the "x" symbol was used along with the "h" on the id tag of a transformer. I have figured that the h represents the "high" side, where power is supplied, but, I cannot find anything about the reason for the x!!??? Can anyone help please?? Any info would be greatly appreciated, thanks!!

[ June 22, 2003, 09:05 PM: Message edited by: eminem ]

 

[bphgravity]

Re: transformer identification

Hello Eminem!

Please see my returned private message sent by you for additional info.

Are you sure it is for a motor and not a transformer? I am not familar with the use of H or X for standard motor connections. If indeed a motor, it could represent the connections for a multi-speed or multi-voltage motor.

The H would most likely be the higher voltage or speed and the X would most likely be the lower voltage or speed.

On transformers, the H represents the higher voltage or primary side of the transformer, whereas the X is the lower voltage or secondary side of the transformer. The numbers after the letter represent the option of connection for desired output voltage on multi-tapped transformers.

Here is a good link to standard motor connections:

http://www.firstelectricmotor.com/motor_connections.htm

[ June 22, 2003, 08:17 PM: Message edited by: bphgravity ]

 

[Ed MacLaren]

Re: transformer identification

The instructor may be testing you.

The letters "H" and "X" are not used to identify motor terminals/leads. For the correct letter identification for motor leads, consult any good textbook that covers motors.

Ed

 

[eminem]

Re: transformer identification

I APOLOGIZE, I WAS DOING SOME WORK FOR MY MOTORS CLASS WHEN I ADDRESSED THE QUESTION. I, OF COURSE, MEANT THE H AND X SYMBOLS ON A TRANSFORMER, NOT ON A MOTOR. I KNOW WHY THEY DECIDED TO USE H, BUT, WHY DID THEY DECIDE TO USE X ON THE LOAD SIDE???!!!

 

[bennie]

Re: transformer identification

If something cannot be identified logically, identify it illogically.

L-1, L-2, and L-3 are assigned to identify line phases. The only illogical symbol left is X.

 

[bphgravity]

Re: transformer identification

I agree with bennie, if the common sense term is taken for something else, make it something odd.

Also, I always assumed it was a take off from the shortened vesion of transformer, "xfrmr"

Since the secondary side is the "transformed" side, X seems to work?

 

[jim dungar]

Re: transformer identification

Just my two cents.

H is for high voltage not for primary
X is for low voltage not for secondary.

H and X are used regardless if the transformer is a step-up, step-down, or autotransformer (buck-boost).

 

[charlie b]

Re: transformer identification

Here is a quote from a textbook that I used during my MS-EE degree program (Turan Gonen, ?Electric Power Distribution System Engineering,? McGraw-Hill, 1986.):

?According to NEMA and ASA standards, the higher voltage winding is identified by HV or H, and the lower-voltage winding is identified by LV or x. Transformers with more than two windings have the windings identified by H, x, y, and z, in the order of decreasing voltage.?

Eminem: This will not fully answer your question, in that it gives only a vague citation of two possible sources, and no indication of the original source. But perhaps it will bring you a step closer.

 

[eminem]

Re: transformer identification

To all who replied, we can all thank bphgravity for giving us the correct answer!!! The x is a shortened identification from xfrmr. My entire class thanks you!! Now that I have found this website I know I can come here to get some great help, and discuss the information I'm learning. Once again, THANK YOU!!!!

[ June 26, 2003, 11:18 PM: Message edited by: eminem ]

 

[bennie]

Re: transformer identification

Within the manufacturers catalog number is a code that will indicate the primary and secondary winding. The reason is tap changers are on the primary side.

Inrush current will be 11 times the excitation current, when reversed.

Cutler Hammer catalog number S20N11SO5A is a 240/480 primary, 120/240 secondary, single phase, 5 KVA, first model, transformer.

Sola/Heavy Duty Transformer catalog number 3H20T2H45S, is a 480 delta primary, 120/208 secondary,45 KVA.

So far I have been successful in getting the GE technical staff to reword one of their technical bulletins regarding reversing transformers. The bulletin now reads, "refer to UL listing instructions and the NEC before reversing the input and output".

I lost the website address. Maybe Don still has this.

[ June 26, 2003, 11:50 PM: Message edited by: bennie ]

 

[charlie b]

Re: transformer identification

Originally posted by eminem: ? the correct answer ? The x is a shortened identification from xfrmr.

I am sure we are all happy to have been of some assistance.

However, you have sparked :roll: my curiosity. Since you claim to have ?the correct answer,? can you now give us your information source? If all you can say is that this is the answer that your instructor called ?correct,? then say that. But I?m inclined to want a definitive source: something that anyone could read (if they could find a copy), and that would lead anyone who read it to understand and agree that this is the ?correct answer.?

Here?s why I am curious. There was a cute article about the use of ?X? in this morning?s Seattle Times. Examples included Xmas, Xtreme, X Files, and X-men. I understand the first item in this list. Our letter ?X? resembles the Greek letter ?CHI,? which is the beginning of someone?s name. But how did ?X? get to represent ?trans,? as in ?xfmr? or ?xfer??

 

[bphgravity]

Re: transformer identification

I believe the term trans means to cross or to change. (transatlantic, transcontinental)

The crossing or changing from one to another can be represented by a cross or "X" like railroad crossing signs and airport names. (LAX - Las Angelas Airport)

I have no documentation of this, nor do I have any other support for my theory. It just seems to make sense.