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Wye-Delta Startup

Wye-Delta Startup

Wye-Delta Startup

(OP)
I need to learn the basics of Wye-Delta startup. I've gotten alot of useful info but just not the basics. For example how does the motor transition from Wye to Delta after startup. I understand that it is based on a timer but what does this look like? A wiring diagram or picture would be very helpful.

Thanks

RE: Wye-Delta Startup

See this. More than you need to know.

http://static.schneider-electric.us/docs/Motor%20Control/Contactors%20and%20Starters,%20NEMA%20Style/Reduced%20Voltage,%20Wye-Delta/Size%206,%20Type%208630SH/50006-026-01E.pdf


The timer controls a set of three contractors arranged so that they can connect the motor windings in star or delta. The timer only signals when two of those contractors need to change state.

Rafiq Bulsara
http://www.srengineersct.com

RE: Wye-Delta Startup

That diagram shows the NEMA (North American) way of doing it, where there is no inherent transition delay other than that which is accomplished by the mechanical interlocking of the contactors. That works fine, but if (when) the mechanical interlocks wear out the result is severe damage.

There are specific [link http://www.pradippowertech.com/pdf/dr_electricals_lv_products/timers/3RP15%20Datasheet.pdf
]"Star-Delta" electronic timers[/link] available, mostly from IEC control manufacturers, that have a transition delay built-in, usually 50ms, so that the Star and Delta contactors are both off for a brief moment. This ensures that there is still a transition delay even if the mechanical interlocks are worn.

 


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RE: Wye-Delta Startup

The 3 contactor method that Rbulsara posted is the most common but I have seen where the 1S and 2M contactors were combined.(1S n/c, 2M n/o) with just two contactors
As an apprentice I also worked on manual starters with a drum contactor. You pulled the leaver up for start (star connection), waited for the motor to speed up then pushed it down (delta connection)where it latched with a solenoid.
Roy

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