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rimpul
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Star Delta Wiring Circuit

08/10/2011 8:05 AM

Hello sir,,

1)Since I'm working on different type of starters can u plz send me the wiring circuit diagram of star delta type starter....

2)I'm trying to run a motor(3 phase) using a microcontroller based code but due to back emf my code gets rebooted again and again...can u plz tell y it happens? and how could I get solved it?
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Anonymous Poster #1
#1

Re: Star Delta Wiring Circuit

08/10/2011 10:57 AM

http://www.bing.com/images/search?q=star+delta+starter&qpvt=star+delta+starter&FORM=Z7FD#x0y0
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Rajesh52
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#16
In reply to #1

Re: Star Delta Wiring Circuit

07/10/2019 8:21 AM

Read More about working of star delta starter

https://sdvelectrical.blogspot.com/2019/03/star-delta-starter.html
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Elroy
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#2

Re: Star Delta Wiring Circuit

08/10/2011 1:13 PM

You have not provided enough information to know for sure what is happening, but here are my thoughts.

1. I very much doubt that back EMF is causing your microcontroller to Reboot. It is more plausible that you have an error in your code and your microcontroller program is stuck in a loop.

2. It is also possible that your source service is insufficient to supply the starting demands of your motor and the resulting voltage drop is causing your problem.

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rimpul
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#8
In reply to #2

Re: Star Delta Wiring Circuit

08/11/2011 3:09 AM

1. I very much doubt that back EMF is causing your microcontroller to Reboot. It is more plausible that you have an error in your code and your microcontroller program is stuck in a loop.

2. It is also possible that your source service is insufficient to supply the starting demands of your motor and the resulting voltage drop is causing your problem.

thanks for your reply..

1) back emf is generated in the starter due to which my code is getting started again and again...

2)power supply to the input is 440v (3phase)
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cuba_pete
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#3

Re: Star Delta Wiring Circuit

08/10/2011 1:19 PM

How did you come to the conclusion that "back emf" is rebooting your code?

What do you mean by rebooting your code?
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rimpul
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#7
In reply to #3

Re: Star Delta Wiring Circuit

08/11/2011 3:01 AM

thanks for your reply.

1)when i connected my motor with starter,the motor gets started by manually turning on..but when i supposed to turn off it couldn't able to switch it off......so i realised that it could be due to back emf.

2)rebooting the code means that it just initialise the again and again and not able to move towards furthur loop.....and my code does not have any errors in it.
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soebfatehi
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#4

Re: Star Delta Wiring Circuit

08/10/2011 10:22 PM

back emf reboots your code?

are you sure it is not a code problem? or a tech problem of some value set points?

like said before - check the capacity of the source first.

is this a college project?
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rimpul
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#9
In reply to #4

Re: Star Delta Wiring Circuit

08/11/2011 3:14 AM

back emf reboots your code?

are you sure it is not a code problem? or a tech problem of some value set points?

like said before - check the capacity of the source first.

thank you for ur reply.

yes i am sure its not with the code its due to the starter where i connect my code...

the capacity of the source is 440v(3phase)
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brich
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#5

Re: Star Delta Wiring Circuit

08/10/2011 11:08 PM

First, this is a school project, yes?

Not a problem but it would help if you say so!

Second, the 3 phase main voltage supply of a "star-delta starter" for a 3 phase motor is isolated from any type of controller for that starter, so there is NO WAY that you have ANY feedback of any type, into your controller software.

What evidence do you have to suggest that is it "back emf" and do you really understand what "back emf" is? Be honest here please.. you'll get more help that way!

so to help you on your quest.. read the following from wikipedia..

The counter-electromotive force also known as back electromotive force (abbreviated counter EMF, or CEMF ) is the voltage, or electromotive force, that pushes against the current which induces it. CEMF is caused by a changing electromagnetic field. It is represented by Lenz's Law of electromagnetism. Back electromotive force is a voltage that occurs in electric motors where there is relative motion between the armature of the motor and the external magnetic field.

One practical application is to use this phenomenon to indirectly measure motor speed and position. Counter EMF is a voltage developed in an inductor network by a pulsating current or an alternating current. The voltage's polarity is at every moment the reverse of the input voltage.

In a motor using a rotating armature and, in the presence of a magnetic flux, the conductors cut the magnetic field lines as they rotate. The changing field strength produces a voltage in the coil; the motor is acting like a generator. (Faraday's law of induction.) This voltage opposes the original applied voltage; therefore, it is called "counter-electromotive force". (by Lenz's law.) With a lower overall voltage across the armature, the current flowing into the motor coils is reduced.

To experience the effect of counter-electromotive force one can perform this simple exercise. With a window closed, lift the switch of an electric window in a car and hold it momentarily and notice the idle RPM drop. The electric motor in the door is stationary and therefore the inrush current will be very high; the alternator will try to provide for the large current which subsequently drags down the engine. As soon as the power window motor overcomes its inertia and starts spinning, back EMF will be produced, exerting less load on the alternator. Hence, the engine speed will return to normal.

the link to the above extract is: http://en.wikipedia.org/wiki/Counter-electromotive_force

Moving on, and again with me doing the research for you... do you think that the "back emf" is caused by the stopping and starting of the motor, that is the opening and closing of the contacts of the contactor?

Then if so you might want to try "back emf suppression", but I don't think it will help.

I am not going to copy and paste the info, just follow the link...(copy & paste it into your browser)

http://www.progeny.co.uk/Back-EMF-Suppression.aspx

As you managed to find CR4, then apply yourself and "google", as I did for you "back emf".. there is loads of info, and if you don't understand the answers then come back, but before you do all that, try asking your teachers.. they are closer and might give you an instant answer.. you never know until you try!

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rimpul
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#10
In reply to #5

Re: Star Delta Wiring Circuit

08/11/2011 3:18 AM

thanks for your reply sir,,

first of all i cant measure the back emf,its just the reverse voltage flowing ,,,so is their any protection circuit available so that i can connect across the coil of the contactor in the starter....
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brich
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#11
In reply to #10

Re: Star Delta Wiring Circuit

08/11/2011 4:43 AM

I gave you the answers earlier.. please read my first post to your problem AGAIN and follow the link I gave for back emf suppression

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LAA_Lucke
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#12
In reply to #10

Re: Star Delta Wiring Circuit

08/12/2011 3:58 AM

#5 gave you all the answers you need.

To help you: first, the control circuits that supply the contactor and the microcontroller are separate from the supply to the motor.

The microcontroller circuit supply is low voltage and has filters for sure.

The code is supposed to close the STAR contactor for a time period and then Open it before Closing the Delta contactor. If your code is not properly written, you might be closing the DELTA when the STAR is not yet OPEN ( Check the Code cycle and make sure that the DELTA closes AFTER few Code Cycles (Ladder diagram or else). If the DELTA Closes while the START is stil ON, a Short Circuit will happen and maybe the cause of a voltage drop affecting the Microcontroller to reboot...(???)

Please check and REVERT.
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brich
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#13
In reply to #12

Re: Star Delta Wiring Circuit

08/12/2011 4:17 AM

hopefully the OP has NOT removed the mechanical AND electrical interlocks to prevent both contactors being energised/closed at the same time. (he asks, shaking his head in disbelief)

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brich
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#14
In reply to #10

Re: Star Delta Wiring Circuit

08/12/2011 4:24 AM

Are you sending a 12 volt signal or whatever voltage from your controller directly to the coil of the contactor to energise the contactor?

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rimpul
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#15
In reply to #14

Re: Star Delta Wiring Circuit

08/26/2011 1:56 AM

no i am not giving 12volts directly instead i m tapping from the input of the 3phase....i mean i have step down it to 12 v and applied.
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krishgen55
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#6

Re: Star Delta Wiring Circuit

08/10/2011 11:17 PM

refer to www.moeller.com website. Download pdf file as moeller wiring star delta.pdf.

It gives all circuits of star delta. wiring manual 2008.
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Anonymous Poster (1); brich (4); cuba_pete (1); Elroy (1); krishgen55 (1); LAA_Lucke (1); Rajesh52 (1); rimpul (5); soebfatehi (1)

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