Third Party Inspection for Switchgear - Procedure

 The Third Party Inspection for switchgear article provides a sample procedure / instruction for switchgear testing and switchgear inspection in manufacturing shop.  You might need to review this article with the switchgear inspection and test plan. 

Switchgear Inspection and testing

This content guides you through all the necessary stages in the production of the switchgears, 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 switchgear and might not be detailed for special cases.

All switchgear 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 switchgear 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.

Third Party Inspection for Switchgear - 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.

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

Third Party Inspection for Switchgear - Material Inspection

The first actual inspection work in the switchgear 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 switchgear drawing datasheet, material list and other specifications as appropriate.

Visual inspection for surface finish and probable defects is done and dimensional compliance with specification need to be controlled, as well.

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 Switchgear - Construction

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

The third party inspector checks the following points on the switchgear, based on the inspection and test plan (ITP), which has already been agreed upon between the purchaser and the switchgear manufacturer.

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.

The third party inspector checks the following items in the switchgear casing inspection process:

  • Surface profile, DFT thickness, paint color and paint type
  • Name plate
  • Outline dimensions, interface dimensions, bus bar dimensions and clearances and other specified dimensions
  • Tightness / torque of terminals
  • Degree of protection

Third Party Inspection for Switchgear - 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.

Third Party Inspection for Switchgear Resistance Test

Switchgear Insulation resistance is measured between control circuits and earth (with sensitive devises excluded) with a 500V Megger.

In the second step Insulation resistance is measured in all applicable permutations for power circuits with a Megger selected to the voltage calculated appropriate to the applicable specification.

The acceptable limit depends to the circuit but normally more than 2 Megohms would not be acceptable.

Third Party Inspection for Switchgear - Withstand Voltage Test (Dialectric Test)

Power frequency voltage of 1.5 kV is applied between control circuits and earth for 1 minute. Then power frequency voltage, calculated appropriate to the applicable specification, is applied to all applicable permutations for power circuits for 1 minute.

The test would be acceptable if no flashover and puncture occurs during the test.

Third Party Inspection for Switchgear - Sequence Test

Circuitry is functionally tested and circuits proven by appropriate tests. The acceptance criteria for sequence test is approved schematic diagrams (including appropriate, recorded, “as built” alterations) and project philosophy

Third Party Inspection for Switchgear - Characteristics Test of Protection Relays

Relay functions and operating curves is observed through primary and /or secondary injection methods etc. The performance normally is in accordance of manufacturer’s data.

Third Party Inspection for Switchgear - Mechanical Operation Test

Third party inspector checks the following mechanisms for operation:

  • Locking
  • Interlocking systems
  • Drawing mechanisms
  • Opening and shutting mechanisms
  • Handling mechanisms
  • Charging mechanisms (trip and closing etc.)
  • Interchangeability.

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 switchgear 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 switchgear.

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 switchgears have been accepted.

 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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