Star Terminal Block Arrangement

[pprendeville]

Hi all,

Query about Star Terminal Block Arrangements. On our notes online, it says “the start ends of each winding (aren't these U1, V1 and W1) must be connected together to form the star point and the finish ends connected to the 3-phase supply.” Should it not be the other way round, i.e. the start ends (U1, V1 and W1) connected to 3-phase supply (L1, L2 and L3) and the finish ends (U2, V2 and W2) connected together to form the star connection ). This is the way it looks to me to be shown in the diagram. Making me very confused.

 

[ajelec10]

in all fairness it doesn't mater which way round you do it?
I would agree with you as i would put the supply on U1 V1 W1 and link out U2 V2 W2

Hope this helps

AJ

 

[supasparxs]

Hi all,

Query about Star Terminal Block Arrangements. On our notes online, it says “the start ends of each winding (aren't these U1, V1 and W1) must be connected together to form the star point and the finish ends connected to the 3-phase supply.” Should it not be the other way round, i.e. the start ends (U1, V1 and W1) connected to 3-phase supply (L1, L2 and L3) and the finish ends (U2, V2 and W2) connected together to form the star connection ). This is the way it looks to me to be shown in the diagram. Making me very confused.

In the motor you have terminals

to make a star connection the links need to be set shorting out the 3 terminals (all terminals on one side) and the 3 phases need to be connected to the other 3 terminals


to make a Delta connection the links need to be set shorting out the pairs of terminals (so you have 3 parallel links) and the 3 phases need to be connected onto one side of each of the links.

I hope I haven't confused you

Richard

 

[pprendeville]

Hi supasparxs/AJ,

I understand what you mean but my point is that the text and the diagram in the attached picture conflict each other.

In the diagram of the motor terminal box aren't the start ends (U1,V1,W1) connected to the 3-phase supply (L1, L2, L3) and the finish ends connected in star. But doesn't it say in the text above it that that start ends should be connected in star and the finish ends to the three phase supply so it's contradicting itself.

But AJ says it doesn't matter which way you do it. I guess the main point is that you don't hook up the star point to the three phase supply as it will create a short circuit.

 

[supasparxs]

to be honest it doesn't make any difference.

you may have to connect the same motor, star, delta or star-delta.

if you are connecting star the feeds to the motor are not connected to any of the links otherwise you will create PFC (Potential Fault Current)

If you are connected the motor in delta the feeds link to one side of each link (but not the other side) otherwise you will create a PFC

On a Star-Delta motor you do not connect any links and you need top connect 6 cores (plus CPC) and the cables are connected to each terminals

the U1, V1,W1,U2,V2 & W2 are only for reference and doesn't really make any difference

Richard

 

[pprendeville]

do you know anywhere on the net that shows examples of a star-delta connected motor. only shows star or delta in our notes.

 

[supasparxs]

do you know anywhere on the net that shows examples of a star-delta connected motor. only shows star or delta in our notes.

No I don't know anywhere buy as it is 2 sets of 3 phase cables (6 cables) connecting to 6 terminals (all links removed) and all the links are in the star delta started.

there isn't anything to see in that diagram

Richard

 

[silva.foxx]

This is one of my examples of YD. Search this site for "star delta".

Look here: Klockner Moeller Motor Controls and Automation

 

[pprendeville]

This is one of my examples of YD. Search this site for "star delta".

Look here: Klockner Moeller Motor Controls and Automation

That's great. Is there software for making circuits like that? Does the control circuit correspond to something like in the attachment? After a certain period of time it changes over to Delta.

Just 2 quick questions.

1. What are R, S and T lines (line voltages?)
2. Overload unit has been set to 58% flc. What's the flc bit stand for?

Looked up that website. Loadsa great info. Once again, much appreciated.

 

[Guest123]

http://www.rotor.co.uk/technical_support/star-delta.pdf

 

[silva.foxx]

That's great. Is there software for making circuits like that? Does the control circuit correspond to something like in the attachment? After a certain period of time it changes over to Delta.

Just 2 quick questions.

1. What are R, S and T lines (line voltages?)
2. Overload unit has been set to 58% flc. What's the flc bit stand for?

Looked up that website. Loadsa great info. Once again, much appreciated.

Software I use for most of my diagrams is Word... using the drawing toolbar.

Yes the control circuit looks suitable, KM1 being Star contactor KM2 being Line contactor and KM3 being Delta contactor. KM2 also provides the Dealy-On timer to switch between Y and D. The triangle between KM1 and KM3 is a mechanical interlock which physically prevents either contactor from closing when one is already closed thus preventing a big bang!

The time period set on the timer is to switch over when the amps from the star start-up drops off.

1. The R, S and T lines are your L1, L2 and L3.

2. Overload (in the shown position) is set to 58% of motor's Full Load Current, found on the nameplate.

 

[pprendeville]

sorry for all the dumb Q's but why 58%. Is that like a rule of thumb. Man you'd be all day using word.

 

[silva.foxx]

QUICK ANSWER: 58% is root 3 = 1.732/3 (3 being each phase)

 

[pprendeville]

Cool. How do I post pics in where I write instead of adding attachments. very handy.

 

[silva.foxx]

I upload my image to photobucket then copy'n'paste the IMG code from there into here!

Thimples!

There's probably an easier way