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Water pump Wye/Delta Starter

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Walden

Electrical
May 4, 2003
46
I am replacing three wye/delta 30kW motor starters. The existing starters are closed transition with a small resistor bank. The client wants to take out the the resistor bank because it frequently burns out and repairs are difficult and expensive. What are the implications of fitting an open transition starter for such an application?
 
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Probably not noticable. Does the pump start OK when the resistor burns out? If yes, that's your answer.

Do you at all need a wye/delta start? They cause more problems than they solve. A soft starter is probably a lot better to put the money in.

Gunnar Englund
 
Hello mpyke

Open transition starters create a very high transient that can cause electrical and mechanical problems and ideally should be avoided, however there are many open transition star delta starters in use in industry. See faq237-613 for more information on the open transition starters.
There is a very good chance that the resistors are not sized correctly to give a true closed transition performance and so the starter is effectively open transition even though it has the resistors fitted.
To work, the resistors need to be sized to handle around star current when in circuit. If they are small resistors rated in watts or even tens of watts, they will no be doing anything.

Best regards,

Mark Empson
 
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