Process of Quality Check on Induction Motor

    Process of Quality Check on Induction Motor

As we know that quality of product is important. Performance or product appearance depend upon the quality of material & components used for manufacturing of product. In Induction Motor there is two stage of quality check. Following are the two stages of quality confirmation:

1.     Mechanical  Quality Check

2.     Electrical Quality Check

Mechanical Quality Check: In construction of Induction Motor in our previous blog we see the different part of Squirrel Cage Induction motor. In this section we discuss about how quality of different part is check & confirm the part for further processing.

1.     Motor Frame: Motor frame is physically check. Frame dimension inside & outside bore diameter is check. Confirm there is no any blow holes or any damage on motor Frame. Measurement of foot mounting holes.(Std. Ref. IS1231)

2.     End Shield: Two End Shields are used in induction Motor i.e. DE side & NDE side. Measurement of end shield inside & outside bore diameter. Measurement of bearing housing diameter .Check any physical damage. If motor is flange mounted then measure the dimensions of bore & PCD of mounting holes & its size. ( Std. Ref. IS 2223 )

3.     Terminal Box & Terminal Box Cover: Measure Terminal Box & Cover dimension & check any physically damage.

4.     Shaft: Measurement of shaft diameter & run out of shaft as per requirement .Check dimension of key slot. Also check threading in side shaft is not damage.

5.     Rotor: Check Rotor dimension & its run out as per requirement. Check any damage of rotor fins.  Check Skew angle of rotor is proper or not.

6.   Stator Core:  Check dimension of stator core & Skew angle is proper or not. Also check the No. of stator slot, its area & construction as per requirement.

7.     Bearing: Checking of proper bearing used & bearing fix exact to required position. There is no any mismatch or damage of bearing during fix. If Ball or Roller bearing are used then check the proper quantity of grease used.

8.    Oil Seal or V-Seal: Physically check the proper Oil Seal or V-seal are used & it is properly fix in required position. There is no any damage during fixing of Oil-Seal or V-Seal.

9.  Cooling Fan: Physically check the Fan for dimension or there is no any loose components on fan that is used for balancing like washer or any other welded part. Also check the no. of Fan Blade & key way dimension if available. 

10.  Fan Cover or Fan Cowl: Physically check there is no any mechanical damage .Measurement of fan cover dimensions. Finger testing on fan cover for confirmation of IP test. ( Ref. Std. IS 4096 or IS/IEC 60034-5 )

11.   Colour Shade : Check colour shade of motor is proper. Check colour thickness by using DFT Meter. ( Ref.Std. IS 5 or as per customer requirement  )

Electrical Quality Check: Performance of induction motor is also depend upon the electrical parameter. Following quality testing is perform for confirmation of electrical quality of material or component used in motor.

 1.     Stator Stamping Core: Check the lamination of stator stamping .Measure the lamination thickness & insulation resistance of stamping. Take core loop test on stator stamping to measure the watt loss in stator core.

2.     Rotor: Check the rotor packet is proper or not .Take growler Test on rotor. This test is useful to determine the any damage in rotor bar or any deformation in rotor is present or not.

3.   Winding & Winding Wire: Wire used for winding is mostly copper wire. Check the insulation of copper wire. Cut 1 Meter or some wire in spool of wire & test the resistance, High Voltage test on that wire. Measure Break down Strength of wire is as per requirement or not by using BDV Tester. Also perform Pinhole test on wire by using Pinhole tester to identify the pinholes presents in copper wire. After making the coil from wire check the dimension of copper coil . Test the resistance of coil. Also take surge test on coil after inserting in stator stamping. Take High Voltage Test on stator stamping.

4.   Insulation Paper: Check the insulation paper thickness is proper or not & check the there is no any damage or insulation paper break. Take H.V.  Test on insulation paper. Measure the insulation resistance of paper. Measure the cutting size of insulation paper is proper or not.

5.    Lead Wire : Check lead wire are properly brazed with winding & also  check the proper size of lead wire used .Terminal marking on lead wire is proper. There is no any insulation damage of lead wire.Termial marking is proper sequence i.e. U, V, W & motor connection star or delta is check. Lead wire connecting lug is tight or not.

6.   Space Heater & Thermistor: If Space heater or thermistor is available in the motor. Then Check the resistance of both space heater and thermistor. Take H.V. Test on space heater.

7.   Earthling Plate or Earthling Marking: Check earthing Plate or earthing marking is on motor.

8.    Name Plate: Check motor name plate details as per require specification & it is place on motor as per required position.

9.   Final Quality Check : After performing above all quality check .Take Routine  test of the motor before packing.