Topics: Starting slip ring induction motors on Soft starter
#1
Start by
Bela Farbas
10-22-2013 02:25 AM
Starting slip ring induction motors
Has anybody got experience with starting slip ring induction motors (induction motors with wound rotor) with a one-step resistor bank and an electronic soft starter?
10-22-2013 04:36 AM
Top #2
Ernesto Wiedenbrug, Ph.D., SM IEEE
10-22-2013 04:36 AM
I have experience monitoring startups of wound rotor and soft starters. What is your application, the particular challenge and the motor's rating - kW, speed, voltage?
10-22-2013 07:22 AM
Top #3
Ernesto Wiedenbrug, Ph.D., SM IEEE
10-22-2013 07:22 AM
I have experience monitoring startups of wound rotor and soft starters. What is your application, the particular challenge and the motor's rating - kW, speed, voltage?
10-22-2013 09:24 AM
Top #4
Jim Zuidema
10-22-2013 09:24 AM
Hi Ernesto,
I've worked on slip ring wound rotor motor circuits, but have never seen one in conjunction with a soft start. Interesting question!
Jim
10-22-2013 11:27 AM
Top #5
Lourenço Moura
10-22-2013 11:27 AM
I have done some start-up in wounded rotor motors. But, like Jim, I've never seen one togheter with a soft starter. Very interesting...
10-22-2013 01:33 PM
Top #6
Don Shaw
10-22-2013 01:33 PM
Wound rotor motors are typically used in applications requiring high starting torques, a limited number of operating speeds, or a stepped acceleration to achieve a soft start. Typically, existing wound rotor applications utilize an electromechanical starter on the stator and introduce multiple stages of resistance in the rotor via contactor arrangements to achieve a soft ramp. Electronic wound rotor soft starters provide greater control of both speed and torque. Most applications consist of two sections, a solid state stator control and a single step of resistors into the rotor circuit from a seperate 3-phse bank. This application provides high torque required in most wound rotor applications and smooth stepless start. The solid state starter is wired to the motor stator control and the resistor and shorting contactor are wired to the motor rotor circuit. The solid state starter accelerates the motor to slip speed and then activates the contactor to short the rotor allowing the motor to accelerate to full speed. If multiple step starting is required for extremely high erertia loads or for continuous opertion at multiple speeds multiple steps of rotor resistance can be used to accomplish this. By naintaining full output voltage to the stator and varying the resistance in the rotor variable speed control cn be attained.
see http://benshaw.cwfc.com/SolidStateControls/spokes/01d-01_woundRotor.htm for more information
10-22-2013 04:05 PM
Top #7
Bela Farbas
10-22-2013 04:05 PM
Thank you for your comments!
To Ernesto Wiedenbrug: The motor with the wound rotor is used to start a primary rock crusher with a large flywheel with very high inertia. Originally it had a muliple step liquid resistor starter. We would like to simplify that by using a solution as I described and Don Shaw described it in more details (see his comment). The relevant motor data is:
Motor 3ph. 220kW, 415V, Rotor 525V, Rotor current 260A.
To Don Shaw: thank you, you hit the nail on the head! Thanks for the link!
Now if somebody could point me to the right direction how to calculate the resistance for my one-step resistor bank that would help me even more.
06-01-2016 09:54 AM
Top #8
Mohamed Ashraf
06-01-2016 09:54 AM
This is a very interesting topic, I have similar situation with 3.3 KV, 500 KW slip ring motor driving a vertical pump.
The problem is the motor was ordered by mistake as slip ring (It should be Squirrel Cage) as the existing MCC is equipped with auto transformer. And there is no source for rotor voltage (675 V / 450 A).
I am interested in knowing if there is an alternative for starting rotor resistance.
06-01-2016 09:55 AM
Top #9
Mohamed Ashraf
06-01-2016 09:55 AM
This is a very interesting topic, I have similar situation with 3.3 KV, 500 KW slip ring motor driving a vertical pump.
The problem is the motor was ordered by mistake as slip ring (It should be Squirrel Cage) as the existing MCC is equipped with auto transformer. And there is no source for rotor voltage (675 V / 450 A).
I am interested in knowing if there is an alternative for starting rotor resistance.
