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coolyaar
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Join Date: Jul 2011
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Star To Delta Starter

11/21/2012 1:10 PM

How much should be the time setting of changeover from star to delta in case of start to delta starter for a 30 kw,380v ,1400 rpm ,58A motor?

What criteria are used to select this star to delta changeover time?
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JRaef
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#1

Re: Star to delta starter

11/21/2012 1:25 PM

Time for the motor to get to at least 80% speed, more if possible. Depending on the load interia, that could be anywhere from 1 second to 15 seconds. But if more than about 15 seconds, you had better have supplemental thermal protection for that motor.

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lyn
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#2

Re: Star to delta starter

11/21/2012 1:39 PM

Haven't you hired an electrician yet?

Star-Delta Motor Starter | EEP
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Joshi
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#3
In reply to #2

Re: Star to delta starter

11/21/2012 2:12 PM

Hard pressed under today's economic realities, saving $$$
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lyn
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#4
In reply to #3

Re: Star to delta starter

11/21/2012 2:38 PM

Well, he's saving $$$ by using us as his free electrical consultants.
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TonyS
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#5
In reply to #4

Re: Star to delta starter

11/21/2012 9:29 PM

Gluton for punishment, he keeps coming back for more.

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Rajesh52
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Join Date: Jun 2019
Posts: 50
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#11
In reply to #2

Re: Star to delta starter

07/11/2019 12:52 AM

Star delta starter is used for starting the large rating squirrel cage induction motor. The starter reduces the voltage by connecting the stator winding in the star.

Star Delta Starter - sdvelectrical
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surenhar
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Join Date: Apr 2012
Posts: 9
#6

Re: Star To Delta Starter

11/21/2012 11:12 PM

its depnd on the load

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PWSlack
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#7

Re: Star To Delta Starter

11/22/2012 5:18 AM

It needs to be long enough to ensure that the de-energising star contactors have cleared the mechanical interlock before the delta contactor is energised and not so long that the motor has idled to a halt before the delta contactor closes.

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JRaef
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#9
In reply to #7

Re: Star To Delta Starter

11/22/2012 1:55 PM
  • "It needs to be long enough to ensure that the de-energising star contactors have cleared the mechanical interlock before the delta contactor is energised and not so long that the motor has idled to a halt before the delta contactor closes."

I think you are referring to the transition delay time, the dwell time during which the contactors switch. I interpreted his question to mean the acceleration time in Star before entering the transition to Delta. But your answer is correct with regard to dwell time for sure.

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Rajesh52
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#12
In reply to #9

Re: Star To Delta Starter

07/11/2019 12:53 AM

CR4 Admin: removed link to virus-infected site
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JRaef
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#13
In reply to #12

Re: Star To Delta Starter

07/11/2019 2:53 PM

WARNING!!!

THIS POST (AGAINST A 7 YEAR OLD THREAD) LINKS TO A WEBSITE THAT IS INFECTED WITH A VIRUS.

DO NOT CLICK THE LINKS.

REPORTED TO ADMINS.

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electricalexpert65
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#8

Re: Star To Delta Starter

11/22/2012 8:45 AM

The chanegover time from star to delta depends upon the motor + load acceleration time, which again depends upon the Moment of Inertia of the Motor and that of the load. There are precise formulae available to calculate the acceleration time once the Moment of Inertias are known.

There are no thumb rules here!
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moan8452
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Join Date: Dec 2012
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Posts: 6
#10

Re: Star To Delta Starter

12/23/2012 6:30 AM

The "changeover time " must be set so the motor is in "best syncronisation" when the delta contactor are activated. (= minimum switching current.)

Best syncronizasion can be measured with an A-meter.

If You change rotation 4 connections have to be changed , not only 2 line cables.
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13 comments

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Users who posted comments:

electricalexpert65 (1); Joshi (1); JRaef (3); lyn (2); moan8452 (1); PWSlack (1); Rajesh52 (2); surenhar (1); TonyS (1)

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