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In my earlier post,you have got information about Direct On Line (DOL) & Star-Delta Starter.In this post,I will disclose details about another Starter which is used to start Wound or Slip-ring Motor.I am giving details about Electricals & Instrumentation because this is also important part of any Air Compressor.My motive is to give you maximum details about Air Compressor.
Wound Rotor or Slip-ring Motor Starter:-
This is called as “Stator-Rotor Starter”.It has two starters,one for the Stator & another for the Rotor.These may be combined in one unit or in seperate parts.
Oil Circuit Breaker (OCB) is employed as Stator Starter.Rotor Starter consists a bank of resistance to put in series with rotor windings during start and
gradually cutout till the winding are short circuited,and the handle locks up in run position.Both are interlocked to prevent the OCB to “ON” when the rotor resistance is completely out of rotor winding and in any 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 closed position,adjust the contacts position,if any gap is visible.
02)Fill Class B-30 Switch Oil,in oil immersed Starter.
03)Check control circuit of starter without operating motor.
04)Fill oil in Dash pot and adjust the Overload Relay setting.
05)Check rating of Back-up (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.
08)Couple Air Compressor to motor,start Air Compressor on unload without interlocking safety devices.Record incoming voltage and current in each phase during observation of 2 hours.Maintain Compressors oil pressure and cooling system in order.
09)Put the Air Compressor on load.Note the maximum curreent drawn by the electric motor to meet the designed working pressure of the air compressor
and the incoming voltage.Observe for 2 hours.
10)Test the Overload Relay by increasing the design working pressure by 1 kilogram per centimeter square.Overload Relay should trip the Starter,if not,
adjust to operate and again check it’s proper working.
11)Interlock the Starter with safety device,as per drawing supplied with panel.
12)Run the Air Compressor on unload condition,to test each switches and confirm the tripping before putting the Air Compressor into operation.
I hope the information given will help you to gain your knowledge about Air Compressor,Electric Motor and Starter.
For more details,please visit.
http://www.pnengineering.blogspot.com/
