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General Category => Maths, Geometry, Physics and others => Topic started by: jupiter1991 on April 12, 2008, 19:30:48 PM

Title: What is this Star Delta automation?
Post by: jupiter1991 on April 12, 2008, 19:30:48 PM
There is another topic bellow that says 'Star delta automation'. I know i could put my question inside but i believe it worths of a new topic.

What is really the star delta automation? And what is the use of it?
Title: Re: What is this Star Delta automation?
Post by: Seawolf on April 14, 2008, 18:26:32 PM
It has something to do with the starting of 3hase big motors because when motors start, they draw a shitload of current. with this star delta they draw less current.
Title: Re: What is this Star Delta automation?
Post by: Alex on April 25, 2008, 13:16:33 PM
The automation is used for motors bigger than 3-3,5 KWats

When the motor starts, it draws from 3 to 9 times (instantly) more current than the nominal current. This will cause the fuses and the thermal protection of the motor to actuate.

The star delta automation is a way to reduce this starting current. It is a rather old way to start a motor as it has been replaced by other automations like soft starter or inverters etc.

The principal is simple. You start the motor by connecting is in star connection. This connection connects each one of the coils to 220V (R-N, S-N, T-N). This way the current is significantly reduced.
After some 5-6 seconds, you switch the connection of the motor to delta. This connection connects each coil of the motor to 2 phases (R-S, S-T, T-R) giving it full power.

Title: Re: What is this Star Delta automation?
Post by: jupiter1991 on August 21, 2008, 20:19:55 PM
Some more help please? Some schematic if possible?
Title: Re: What is this Star Delta automation?
Post by: spic0m on August 22, 2008, 11:09:05 AM
The attached pdf is property of Rockwell automation, if it is not allowed to be in here please mail the admin and it will be removed at once. Apart from this i think you find it very explanatory, otherwise i can post something more simpler.
Title: Re: What is this Star Delta automation?
Post by: jupiter1991 on August 22, 2008, 16:23:29 PM
Thanks spicom, i will check it out