Star Delta Connection Diagram

You seem to be rather anxious, so i will help. But....

1. Please register on CR4, read its terms and conditions, go through the FAQs and then post questions.

2. Please post one question only once.

3. Please search the web first before posting here.

Here is one diagram, not from google, but from my own library ....

OK, Mr Rao is right that we of this forum must give more professional advice.

Here is one caution : There should be a time delay between Star contactor dropping off and Delta contactor picking up. This is to prevent the possibility of the 3-phase dead sgort circuit happening if the arcing zone in the star contactor is still in an ionised state when the delta contactor picks up. So, there are special Star/delta timers available, with a 'transition' delay ... about 30ms for <50HP and 100ms for bigger motors. Both pneumatic and electronic timers are available. One may say that the motor will slow down in this transition time and that will result in a current surge, but in reality, i have studied this in depth, and inertia keeps them going, and no untoward effects are there.

Hope this helps.

There are two diagram. Which one has to follow?

Dear Guest,

Are you the original poster? i mean, are you the one who asked for the diagram in the first place ? If so, please register on CR4. It is simple, free and useful.

There is a power circuit diagram and a control circuit diagram i have given. BOTH are to be used. If you do not know how to wire it up, you better leave it to someone with more knowledge.

RAJ089... are you listening? Do you still think i was unprofessional ?

Which one of the following Star-Delta Starters?

i) Manual Star-Delta Starter

ii) Semi-Automatic Star-Delta Starter

iii) Fully Automatic Star-Delta Starter - Closed Transition

iv) Fully Automatic Star-Delta Starter - Open Transition

There are further options like Closed Transition with or without resistors, etc.

Please be more specific.

It seems no body understood your Question/ connections. Please explain so that we can reply or learn from this.

Thanks

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Star Delta connection diagram in motor terminal box

The automatic start delta motor starter is used to limit the starting current of induction motor. The circuit diagram of start delta starter is as given below.

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here it is for both the guests.

Have a connection for Mr Sridher. Hope I have your permission to send this diagram.

I am sorry, I did not ask u first.

However, I have a question on control diagram---

K1T on main diagram is not clear, how it came up.The symbol for K1T also needs explanation as Google did not help me.

Would u please explain the control diagram to my electrician as he is boggled by this.

I Thank u

Of course you have my unqualified permission to share whatever i may have said Raj, even in future, it would be my pleasure to have been of some help to someone

Later tonight, i will try to explain the control diagram better, please bear with me, thanks.

The K1T is a timer, shown as a separate product for this general purpose schematic. On smaller contactors, it is mounted on the Star contactor KM1 itself, so no separate coil is there for it.

i give below a few images which should explain the operating sequnce..

The pneumatic timer is an add-on accessory which is mounted on the star contactor. In such a case, the time-delay NC deenergises the star contactor and its NO energises the Delta contactor KM2. Mechanical and electrical interlocks are a must.

However, i have found it necessary to insert a "transition delay" when changing from Star to delta, to prevent any ionised gases in the star contactor causing a short-circuit. Such special timers are available in both electronic and pneumatic versions.

Hope this is somewhat clear? If not, please feel free to ask.

Cheers.