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Topic Title: Star delta timer.
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Created On: 31 July 2012 09:58 PM
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 31 July 2012 09:58 PM
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hertzal123

Posts: 331
Joined: 26 August 2007

Wired a sd starter starter today and the timing module had time adjustment for transition between star and delta( in ms) as well as the normal start/run timer in seconds.I was under the impression that the transition was supposed to be as fast as possible,so why the time adjustment?
Regards,hz.
 31 July 2012 10:32 PM
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RookieSpark

Posts: 6
Joined: 28 November 2008

Normally the delay timer enables the motor time to run up to full rpm speed. When this speed is achieved it can make use of the full load power available in the delta configuration. If the motor was given the power available in delta before it got up to speed it would have this power in its windings which it couldn't really use. This power would be wasted heat which the windings would have to try and dissipate. Overheating the motors windings is not desirable. So the delay timer can be used to ensure the delta contactor is not brought in until the motor has run up to normal speed, once at this speed the delta contactor is brought in and the motor now has available the full load power.

Edited: 31 July 2012 at 10:52 PM by RookieSpark
 01 August 2012 04:15 AM
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aiza

Posts: 1
Joined: 01 August 2012

Hi,

Why star delta timer required for motor? what does it do?








Wink-
Aiza
 01 August 2012 04:48 AM
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jleltd

Posts: 199
Joined: 11 March 2009

The dwell time between star and delta is to help any mechanical interlocks between the star and delta contactors not jamming up also stops the risk of the delta and star contactors being made together for a minute period on the changeover. With both electrical and mechanical interlock this should not be a problem though.

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James
 01 August 2012 06:30 AM
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ebee

Posts: 5815
Joined: 02 December 2004

Timers! what luxuries!

I used to work in a factory where the operators had to set the lever to "Start" then wait for motor to get to speed then select lever to "Run" on lathes

Oh happy days.

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Regards,
Ebee (M I S P N)

Knotted cables cause Lumpy Lektrik
 01 August 2012 07:44 AM
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Jaymack

Posts: 4799
Joined: 07 April 2004

Originally posted by: ebee
I used to work in a factory where the operators had to set the lever to "Start" then wait for motor to get to speed then select lever to "Run" on lathes

Probably using Ye Olde, Ellison oil filled starter with the drop tank, down for Start and oop for Run. The days of the salt water starter, hand wound down for 3 phase, wound rotor starting, sometimes automatic.

Nostalgia ain't what it used to be!

Regards
 01 August 2012 07:59 AM
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Ricicle

Posts: 851
Joined: 23 October 2006

I liked one of our old rubber mixers that had a slip-ring motor. The resistance of the rotor being gradually altered by turning a wheel which controlled a resistor bank immersed in oil. Happy days !

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Empty barrels make the most noise.
 01 August 2012 07:44 PM
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slittle

Posts: 3597
Joined: 22 November 2007

I've got a grain fan that's started like that.

It's been there years and years and still behaves nicely.

I can see the day coming when just as the silo's are filled up with warm grain that needs cooling, either the motor or more likely the starter will refuse to play nicely.


Stu
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