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Member

Join Date: Mar 2010
Posts: 8

Soft Starter and Star Delta Starter

04/01/2010 1:32 AM

In my project i had 3 X46 kw submersible pumps is there,my controlpanel supplier showing soft starter in SLD.what is difference between soft starter and normal automatic star delta starter

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Guru

Join Date: Feb 2009
Location: Houston, USA
Posts: 971
Good Answers: 244
#1

Re: Soft Starter and Star Delta Starter

04/02/2010 5:28 PM

This should have been asked in Electrical Engineering forum. Anyway here is the answer:

Start-Delta and Softstarter are both the starting method of induction motors for reducing the motor starting current. However, they are quite different in their functionalities and constructions.

Start-Delta starter: It is a starting method that reduces the starting current and starting torque. The device normally consists of three contactors, an overload relay and a timer for setting the time in the star-position (starting position). For the starting period (time set by the timer), the motors windings are connected in start (Y) and then the connection is changed to delta during normal run. Because of the start connection, the starting current is 1/3rd of the DOL (Direct-On-Line) starting; however the starting torque is also 1/3rd of the DOL starting torque. For this type of starting, the motor windings must have both ends (2 terminals for each phase, total 6 ends) terminated in the terminal.

Softstarter: A softstarter is an electronic device which controls the voltage during the starting period with having thyristors in the main circuit. As the motor voltage is low during start with soft starter starting, the starting current and starting torque is also low. It contains the motor protection capability and hence separate motor protection relay is not required. It is also used to control the motor start/stop. Soft starters can be used for both LV and MV voltage motors.

For more details, see these links:

http://www05.abb.com/global/scot/scot209.nsf/veritydisplay/2985284834bcff7fc1256f3a00274038/$File/1SFC132002M0201.pdf

http://literature.rockwellautomation.com/idc/groups/literature/documents/wp/150-wp004_-en-p.pdf

http://www.fairford.co.uk/userimages/_files/soft_start_docs/sd0018802__basic_soft_starter_principles.pdf

http://www.mandc.co.za/pdfs/Star_Delta_Starting_and_Dual_Voltage_Motors_Explained.pdf

- MS

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Commentator

Join Date: Oct 2009
Location: Dubai,UAE
Posts: 59
Good Answers: 1
#2
In reply to #1

Re: Soft Starter and Star Delta Starter

04/12/2010 4:34 AM

Nicely defined...keep it up

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