Star Delta Starter For a 500 KW Motor

I am not sure about this but i studied above 50KW we use auto-transformer as starter and i heard of salt-water using for some kind of starting purpose which you need to search on.

yes star delta starting is possible for a 500kW motor with six terminals . . . the choice of starting will be determined by the condition of your bus and the nature of load . . .

the benefits will be a limiting of starting current and the avoidance of a dip on the bus during starting . . .

more can be said if you share what the motor is driving? is it a geared motor?

You can get a Star-Delta starter for any size motor available. But the motor must be capable of being started this way.

There are MUCH better ways to start large motors however, Star Delta is the lowest cost but is hands-down the worst option. It can be hooked up incorrectly in any future service, it can be mis-applied and damage the machine, it will create disturbances in the AC service that may damage other equipment in the facility and the motor. There are no other viable advantages over other methods of reduced voltage starting.

Solid State or even Autotransformer starters are a much much better choice and will work on any AC motor, no need to make sure it is capable of being used with the starter.

Thanks

hithuanand, Re: "salt water" starting. That is something done for a special kind of AC motor called a Wound Rotor Induction Motor where the rotor has windings that are connected by slip rings. In that motor design, changing the resistance in the rotor changes the torque carachteristics of it and thereby the slip and then speed (in an indirect fashion). One way of varying the resistance is to use tapered resistor "probes" that are rasied and lowered into an electrolyte solution to short out a percentage of them and change the rotor resistance. They are specialized and complex and like Star-Delta cannot be used on just any motor.

So star-delta is used for SCIM which are prefered for pumps,blowers,mills etc. I got a doubt now in SRIM stator windings are always in delta or star.

Yes! It is possible! Let me calculate!

500kW motor's FLC would be 869A and the phase current would be 502A. Air-break contactors are available epto 650A (in L & T MNX Series).

Having worked on 600KW closed transition star /delta starters I wouldn't recommend them. As for open transition starters, don't even think about it!

As others have said there are far better ways around the problem.

just in case you love to read . . . http://www3.sea.siemens.com/step/pdfs/cc_3.pdf