Stator-Rotor Starter is used to start the Wound or Slip-ring Motor.
Actually, Stator-Rotor Starter is a very old technology to start the electric motor.
Still, some engineering units are using this old technology, if you are from them, you will get help from this post.
If you are using Automatic Starter to start the motor, read this article,
Wound Rotor or Slip-ring Motor Starter
This is called” Stator-Rotor Starter”. Hence it has two starters, one for the Stator & another for the Rotor.
These may be combined in one unit or in separate parts also.
Oil Circuit Breaker (OCB) is employed as Stator Starter.
Rotor Starter consists of a bank of resistance to put in series with rotor windings during start and gradually cut out till the winding is short-circuited, and the handle locks up in the run position.
Both are interlocked to prevent the OCB from “ON” when the rotor resistance is completely out of rotor winding and in an intermittent position.
Care to be taken to fill up clean switch grade (Class-B-30) oil from sealed containers from reputed manufacturers.
Commissioning of “Stator-Rotor Starter” and “Air Compressor”
01) Check fixed and moving contacts for any gap in a closed position, and adjust the position of the contacts, if any gap is visible.
02) Fill Class B-30 Switch Oil, in oil-immersed Starter.
03) Check control circuit starter without operating motor.
04) Fill oil in Dashpot and adjust the Overload Relay setting.
05) Check the rating of backup (HRC) fuse, and power cable connections.
06) Check Starter-Motor connections.
07) Run the motor for 2 hours in idle condition. Record the incoming Voltage & Current in each phase.
Maintain Compressor’s oil pressure and cooling system in order.
09) Put the Air Compressor on load. Note the maximum current drawn by the electric motor to meet the designed working pressure of the air compressor and the incoming voltage also. Observe for 2 hours.
10) Test the Overload Relay by increasing the design working pressure by 1 kg/cm².
So, the Overload Relay should trip the Starter (Stator-Rotor Starter), if not, adjust to operate and again check its proper working.
11) Interlock the Starter (Stator-Rotor Starter) with a safety device, as per the drawing supplied with the panel.
12) Run the Air Compressor on unload condition, to test each switch and confirm the tripping before putting the Air Compressor into operation.
Over to You
I hope the information given about Stator-Rotor Starter will help you to gain your knowledge of Air Compressor, Electric Motor, and Starter (Stator-Rotor Starter).
Besides this information, you are suggested to read something more from below engineering books
Also to get the more details about the topic, I further recommended reading
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