ELECTRIAL AC SLIP RING MOTOR

Not enough information, but a first guess would be that you have too little resistance at startup.

KINDLY TELL WHAT FURTHER DETAILS YOU NEED, BUT YOUR SUGGETION IS VALUABLE.

Let's start with this: Do you understand how a slip ring induction motor works? If you do, then what is the nature of the load and how are you accelerating it? Liquid Resistance? Stepped resistance? If stepped, how many steps and how much resistance in each step? If you don't know all of this, then has anyone done a starting analysis comparing the necessary accelerating torque of the load and the motor torque/speed curves of the motor with the various rotor circuit resistance amounts?

And please stop using your Caps Lock. I know it might make it easier for you to not have to worry about proper capitalization, but it makes it more difficult for people to read it. Reading types text is more than just looking at letters, we also look at the shapes of words in order to process known words faster. When you use all caps, if forces the reader's brain to slow down and r e a d e a c h l e t t e r s e p a r a t e l y, which I for one find frustrating. Plus it is considered the equivalent of shouting and deemed rude.

Sorry for caps lock writing, I know very well of slipring induction motor. We are using 800 hp slipring motor for running ribbed bar(using for civil construction) rolling mill of 14". Rotor is added with water resistance using ss plates dipped in caustic soda water. When motor starts plates are small deeped in water and then we graually start deeping plates by screw operated handle, after we reach to full speed & reduce starting current, we short all water resistance by copper short link.

You are using a LRS.Ok.Now what is the material of slip ring? copper, Cupro nickel?Observe whether solder run out is there.Best solution is to use a slip ring motor with automatic brush lifting and short circuiting arrangement where the slip ring come in only during starting.The advantage of slipring motor at starting and running like cage is obtained.Check your motor carefully.many times the leads coming to slip ring gets damaged due to sudden jerks in starting or stopping.by the what is the application? how soon u take to cut off the resistor? is it motorised?

Dear Mr.AshokTakali,

Pl. check for the following.

1. Grade of the Carbon Brushes and its hardness.

2. Quality of Slip Ring whether it is commercial copper ir IE grade.

3. What is the starting current and how long that is How Many Seconds the motor takes to accelerate to full speed.? Here the GD^2 Value of the revolving equipment comes in to picture.

4. Whether the Starting Torque developed is as per the design,?

5.Whether the Motor is started against Load or the Motor is started and then load is put.? If it is started against load, then additional resistance is required in the starter, while starting only.

Pl.post the information, what was the problem, and solution arrived.

DHAYANANDHAN.S

In slip ring motor the starting current and starting torque are dependent on external resistance and you can have a starting torque as high and equal to POT.