Terms

[Motortester]

I'm writing testing and troubleshooting instructions about polyphase induction motors. Because the company i'm working for is Finnish but wants the instructions in English, it is very hard to translate terms sometimes.

My question is know: Are there any official terms in English for the U1, V1 and W1 leads, as well as the U2, V2 and W2 leads?

(In Finnish we call them something like "beginning ends" and "finishing ends".

 

[magneticted]

Hi Motortester

The terminal markings are defined in IEC34-8. In IEC their is no particular term, and for instance a motor with 6 ends are ditinguished by a capital letter, eg U1,V1,W1 & U2.V2,W2

We normally call them stator connection leads, or stator termination points.and identfy them by their respect capital letters.

Regards

 

[laundry]

HI Motortester
magneticted is absolutely correct.

Barry.

 

[Motortester]

Okay, thanks!

I have to formulate the sentences a little differently then.

 

[aolalde]

In USA according to NEMA MG1 the points of connection are "TERMINAL LEADS" and identification numbers or letters are "TERMINAL MARKINGS"

 

[Motortester]

Yep, I have seen those NEMA terms, but they are not precise enough for me. I think there should be different names for the U1,V1,W1-leads (the leads where the power supply usually is connected to and the U2,V2,W2-leads which can be Y-connected. I understand that the lead markings and power supply can be changed the other way around and the motor still functions as before.

But, for example, when one of the phase windings are reversed for some reason the leads markings are usually wrong. When I write my instructions it is not enough if I write that "switch places between the U1 and U2 leads". In the troubleshooting instructions I want to explain precisely where the error is and why. Then I just think it would be easier to say like this:

"The current of one phase flows in the wrong direction because the [starting end] and [back end] of any of the three phase windings has switched place."

What do you guys think? Am I completely off track?

 

[laundry]

HI Motortester.
Have read your last coment I think this is what you are looking for ie If the motor runs in the wrong direction, change over L1 with L2 this will change rotation,But if your motor is a star/delta and the motor stalles when changed to delta you have the same phase ie red to red on say U1 and U2.
REGARDS

Barry.

 

[petronila]

Hi Motortester,

About your inquiry, The Letters and Numbers combination belongs to IEC STANDARD TERMINAL MARKING and in NEMA STANDARD are equal to: U1=1 V1=2 W1=3 U2=4 V2=5 W2=6.

This Terminal markings means the Beginning and end of each phase winding group. For the Three Phase called a,b,c(Nema) you have: Phase a: Beginning U1(1) and End U2(4),Phase b: Beginning V1(2) and End V2(5) and phase c: Beginning W1 (3) and end W2 (6) ussually when you have an electric motor with 6 leads you can make two connection called Star and Delta. Star: Join U2-V2 and W2 and Conect the power source to U1-V1 & W1 and DELTA: Join U1&W2 Join U2&V1 join W1& V2 and you connect power to each join.

I think you are trying to explain if you don´t perfom well this joint your are gonna have a bad connection, and is true.

Regards
PETRONILA

 

[petronila]

Hello Motor Tester,

I would like to clear something in my last answer, the terms Beginning and end usually are called in USA like COIL END.

Then U1,U2,V1,V2,W1,W2 are COIL ENDS (In winding terms) and are called LEADS if you are talking in external motor connection terms.

I hope this can help you.

Regards

PETRONILA