3 PHASE STAR (WYE) DELTA CONNECTED LOADS

[elecspark]

Hi, I am interested in learning more about the actual current flow and voltage differnces between the Delta connected load or motor and the star or (wye) connected load or motor. I am after a web site that has a good reference to the formulas and characteristics of the 3 phase star (wye) / delta motor starting principle. I have read tech books on the subject but haven't found an online reference site. The reference site would also have information that informs of the different methods that motor manufacturers use to bring out the winding leads of 3 phase motors and how they are connected internally either by using the star or delta methods, or end user selectable (using jumper links across the terminal posts). Any info on this subject is appreciated Thanks in advance.

 

[jbartos]

Suggestion: Visit

http://shop.emotorstore.com/estore/TD_Terminal_Markings.asp?

etc. for more info
There are many web sites dealing with motor connections including delta and wye. It may also be a good idea to visit a technical library that could be more informative and efficient resource on this topic than the websites.

 

[jbartos]

Small encore: Visit

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

http://www.usmotors.com/Service/faq9.htm

etc. for more info

 

[busbar]

IIRC, electricpete posted this—

http://www.joliet-equipment.com/EASA_handbook.htm

with respect to motor connections.

 

[busbar]

Addressing: “characteristics of the 3 phase star (wye) / delta motor starting principle…” It is not apparent if you are looking for ANSI- or IEC-based systems.

On the North American continent, for choices in electromechanical reduced-voltage starting, Y-∆ starting is only one of several. Based on servicing French, German and Italian food-production equipment, looks like Y-∆ starting is [or has been] on top in Europe for what seemed to me to be surprisingly small motors, like 2-5 Hp. I assume a major factor is the variations in engineering practices stemming from differing customs and philosophies of line lengths and transformer placement.

In the US and Canada, there are a wide range of practices, but my gut feeling is the six-lead split-coil motor is not very common, and is typically specified and purchased exclusively for applications where a plant has experience with and thus favors Y-∆ starting.

For larger low-voltage motors; ~500Hp, there are two forms of Y-∆ starting—open transition and closed transition. Open transition is less expensive, has fewer parts but with an electrically ‘rougher’ changeover between the two modes. Closed transition in a bit more pricey, with an additional contactor and resistor bank, with potentially smoother start-to-run-mode switching.

However interesting, there is only so much knowledge ‘out there’ on the practice of electrcomechanical reduced-voltage motor starting. As for not finding suitable online information, I think you may have not devoted perspiration and enthusiasm to looking.

http://www.google.com/search?hl=en&q=wye-delta+motor+starting&btnG=Google+Search

[770 hits tallied.] What specific queries do you have in regard to discrete aspects of the cited material? This will likely commit to beeter use of resources. Unfathomable as it may seem, people have waited six weeks for the public library to forward a hastily produced, third-generation free-of-charge photocopy of an entry found on a backroom shelf of some corporate bound-journals annex 120 miles distant.

However opportune it may seem, a mistake is to assume the internet should be your total source of knowledge. One of the best uses of the internet is locating transactions abstracts and book descriptions and reviews. There’s a lot to be found in college engineering libraries. More and more info is placed on line all the time, but we are a long way from books being obsolete. Information won't fall out of the book in to your lap—or brain—either; particularly pared and sorted in your most convenient form.

Although they will never be universal, AC solid-state soft starting and variable-frequency drives are having a strong effect on the market. There are still a lot of DC drives in service with probably the widest range of mechanical-output powers.

One US producer has info at:

http://www.ab.com/manuals/ms/RVS.htm

but understand this is information presented from the manufacturer’s point of view, and may limit the full picture.

We are all guilty of sometimes having a “well frog” view…stuck at the bottom of a dark cistern thinking we must really be swimming in the ocean.