Third Party Inspection for Induction Motor

The Third Party Inspection for Induction Motor article provides you with information about the induction motor test and induction motor inspection in a manufacturing shop.

You may need to review this article along with the following article:

Third Party Inspection for Induction Motor

Inspection and Test Plan (ITP) for Induction Motor

This content guides you through all the necessary stages in the production of the induction motors, including the raw material, final inspection, preservation and packing, and dispatch to site.

You need to take this point into account: this article is written for a typical induction motor and might not be detailed for special cases.

This content may be useful for second party inspectors, induction motor quality control personnel, engineering companies, and purchasers, as well.

All induction motor inspection and testing is done against the approved drawings, purchase order specifications, purchasers or company standards, and within the practices and rules of the country, state or province and any government decrees, laws, ordinance or regulation as may apply.

The applicable codes and specifications for a induction motor that is under the construction process is:

  • Design code and Standard
  • Purchase order specification
  • Purchaser's standards
  • Approved drawings

The applicable codes and standards may be based on any international standards. This content is general and can be useful for all recognized standards.

Required Documents for Third Party Inspector Review:

The list of documents normally is agreed upon in the Pre-Inspection meeting, which is held several weeks before the actual commencement of the inspection work.

The parties that participate in this meeting are the manufacturer, purchaser and third party inspection agency representatives.

This is already explained in the Inspection and Test Plan for Induction Motor article.

These are the list of documents that are normally agreed upon to be presented to the inspector:

  • Induction Motor Purchase Order or Contract
  • Induction Motor Manufacture Proforma Invoice
  • Induction Motor Manufacture Quality Control Plan
  • Induction Motor Inspection and Test plan
  • Induction Motor Data Sheet
  • Induction Motor Approved Drawings, (arrangements, schematics, wiring, single line)
  • Induction Motor Raw Material Test Reports
  • Weld procedures and Procedure Qualification Records (if applicable)
  • Induction Motor Calibration Certificates for Test Equipment
  • Induction Motor Special Procedures
  • Induction Motor Special Qualifications
  • Induction Motor Preservation, Packing and Shipping Procedure
  • Induction Motor Packing List

Third Party Inspection for Induction Motor - Material Inspection

The first actual inspection work in the induction motor is the raw materials inspection.

The original or authenticated copies of mill certificates of material normally are available at the manufacturer's premises.

The third party inspector examines these certificates for compliance with specifications, and where appropriate, drawings.

The review includes checks on:

  • Maker’s name and location
  • Certificate number, grade
  • Batch number
  • Chemical composition
  • Mechanical properties
  • Cast or Heat number (for metal parts)
  • Heat treatment condition
  • Surface finish
  • Structural observations, notable defects

Ancillary items may be supported by test certification, or by certificates of conformity. It is necessary the content of certification to be appropriate to the required scope of the items.

Then the inspector witnesses the materials identification on the certificates against the materials marking. It is also necessary to check these with the induction motor drawing datasheet, material list and other specifications as appropriate.

When the third party inspector carries out the material inspection, then provides the inspection visit report (IVR), the report contains the following items:

  • Confirmation of satisfactory document review
  • Record of the endorsement of certification reviewed/witnessed
  • Record of all non-conformities
  • Record of any tests witnessed and the result

Third Party Inspection for Induction Motor Construction

When the induction motor raw material inspection is carried out, and the results were satisfactory or non-conformities were closed by remedial action, then the induction motor manufacturer will start fabrication.

The inspection scope is determined in the ITP. Some purchasers prefer to have stringent controls and assign the TPI for more “hold or witness points” for inspection and test activities, and some others prefer less “hold or witness points” and assign the TPI much more work in the “review document.”

This depends in the inspection budget, which purchasers assign for inspection. Much more inspection will have a much larger cost and less risk, and conversely, less inspection will have less cost but more risks.

For more details, review the Inspection and Test Plan for Induction Motor article. There is a draft of the ITP in this article, which we believe is the best practice for induction motor inspection.

The third party inspector (TPI) checks following in accordance of approved drawings and applicable standards:

  • Paint using specified colour swatch, measure thickness, if specified
  • Name plate
  • Outline dimensions, interface dimensions, bus bar dimensions and clearances and other specified dimensions
  • Tightness / torque of terminals
  • Degree of protection

If the third party inspector is not in the hold or witness point in the ITP for this inspection stage, then he/she will review the induction motor manufacturer quality control report in his/her coming visit or on the final inspection day.

Third Party Inspection for Induction Motor - General Arrangement Check

The third party inspector checks that all instruments, compartments, control switches etc. are correctly rated and are correctly located, with specified labelling.

The inspection is carried out in accordance of approved drawings.

Similarly, If the third party inspector is not in the hold or witness point in the ITP for this inspection stage, then he/she will review the induction motor manufacturer quality control report in his/her coming visit or on the final inspection day.

Third Party Inspection for Induction Motor - Winding Resistance Test

Induction motor resistance between terminals of each winding is measured by means of double bridge method.

The test would be acceptable if imbalance value is within + or - 3%.

Similarly, If the third party inspector is not in the hold or witness point in the ITP for this inspection stage, then he/she will review the induction motor manufacturer quality control report in his/her coming visit or on the final inspection day.

Third Party Inspection for Induction Motor - No Load Test

Each phase current and input power are measured in operating under rated frequency, rated voltage, and no load.

The test would be acceptable if Imbalance value of each phase current is within + or minus 5% of mean value.

Similarly, If the third party inspector is not in the hold or witness point in the ITP for this inspection stage, then he/she will review the induction motor manufacturer quality control report in his/her coming visit or on the final inspection day.

Third Party Inspection for Induction Motor - Locked Rotor Test

While locking rotor, the voltage, current, and input power are measured under rated frequency and rated current.

The test would be acceptable if the measured values are in specified ranges.

Similarly, If the third party inspector is not in the hold or witness point in the ITP for this inspection stage, then he/she will review the induction motor manufacturer quality control report in his/her coming visit or on the final inspection day.

Third Party Inspection for Induction Motor - Low Frequency Locked Rotor Test

While locking rotor, the voltage, current, and input power are measured under half rated frequency and approximate rated current.

The test would be acceptable if the measured values are in the specified ranges.

Depending to the ITP the third party inspection for induction motor either witnesses the test or will review the Induction Motor manufacture quality control test report in the coming visit or in the final inspection day.

Third Party Inspection for Induction Motor - Determination of Characteristics

The following characteristics are calculated by induction motor manufacturer and is reviewed by third party inspector.

  • Current, efficiency, power factor and slip
  • Maximum output power
  • Maximum torque
  • Starting current
  • Starting torque

The obtained values from calculation would be acceptable if they are in the range of specified values.

Third Party Inspection for Induction Motor - Temperature Rise Test

The temperature rise is measured for following parts operating for rated time by means of equivalent load method.

  • Stator winding
  • Stator core
  • Bearing (Coupling side and free side)
  • Centre of frame
  • Inlet air
  • Outlet air

The test would be acceptable if the measured values are in the specified ranges.

Similarly, If the third party inspector is not in the hold or witness point in the ITP for this inspection stage, then he/she will review the induction motor manufacturer quality control report in his/her coming visit or on the final inspection day.

Third Party Inspection for Induction Motor - Resistance Test

Induction Motor Insulation resistance is measured between winding and earth (using 1000V Megger) and between Accessories circuit and earth (using 500V Megger).

The test would be acceptable if measured value between winding and earth is over 10 Mega-ohm and between Accessories circuit and earth is Over 1 Mega-ohm at the normal temperature.

Similarly, If the third party inspector is not in the hold or witness point in the ITP for this inspection stage, then he/she will review the induction motor manufacturer quality control report in his/her coming visit or on the final inspection day.

Third Party Inspection for Induction Motor - Dielectric Test

It is necessary to confirm that the voltage provided in the applied specification is withstood between stator winding and earth. If JEC-37 applies, the following formula is used.

2E + 1000V (50HZ or 60HZ) for 1 minute, the E is rated voltage

The test would be acceptable if withstood without any damage.

Similarly, If the third party inspector is not in the hold or witness point in the ITP for this inspection stage, then he/she will review the induction motor manufacturer quality control report in his/her coming visit or on the final inspection day.

Third Party Inspection for Induction Motor - Vibration Test

Induction motor vibration is measured in operating the motor at no load condition with rated voltage and frequency. The location of vibration measurement is at both bearing housings.

Measuring directions are in horizontal, axial and vertical positions.

The test would be acceptable if measured values are within the specified values.

Similarly, If the third party inspector is not in the hold or witness point in the ITP for this inspection stage, then he/she will review the induction motor manufacturer quality control report in his/her coming visit or on the final inspection day.

Third Party Inspection for Induction Motor - Noise Test

Induction motor noise is measured in the motor at no load condition with rated voltage and frequency.

The 4 points at each 90 degrees are measured, where height of the points is shaft height for horizontal motor and one-half of motor height for vertical motor.

The test would be acceptable if measured values are within the specified values.

Similarly, If the third party inspector is not in the hold or witness point in the ITP for this inspection stage, then he/she will review the induction motor manufacturer quality control report in his/her coming visit or on the final inspection day.

Third Party Inspection for Induction Motor - Visual Inspection

The induction motor is visually inspected for outside view such as rust, scratch, and bruise, coasting color and finish, description on name plate, mounting direction of terminal box and Protection type of frame.

Third Party Inspection for Induction Motor - Dimensional Inspection

The induction motor is dimensionally controlled for shaft end diameter, shaft length, key and keyway, pitch of bolt holes including bolt holes, height of shaft center and principal outer dimensions.

The test would be acceptable if measured values confirm drawing values.

Third Party Inspection for Induction Motor - Reporting:

The third party inspector provides an Inspection Visit Report (IVR) after each visit, as well as a final report summarizing the activities carried out during the induction motor production in accordance with the contract requirements and circulated within the time limits specified in the contract.

The report is in the format required by the client and clearly indicates final acceptance or rejection of the induction motor.

Third Party Inspection for Induction Motor - Release Note:

When required by the contract or purchase order, a release note is issued by the third party inspection agency and given to the manufacturer when the induction motors have been accepted.

Third Party Inspection for Induction Motor - Packing, Marking and Shipping:

The following points are checked by the third party inspector:

  • Verify that the packing materials conform to specifications and accepted practice for the mode of transport
  • Verify protection against humidity, abrasion, distortion and other damage.
  • Verify shipping marks to marking instructions and record.
  • Verify handling marks.

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