The Third Party Inspection for Gas Circuit Breaker article provides a sample procedure / instruction for Gas Circuit Breaker testing and Gas Circuit Breaker inspection in manufacturing shop. You might need to review this article with the Gas Circuit Breaker inspection and test plan.
This content guides you through all the necessary stages in the production of the gas circuit breakers , 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 gas circuit breaker and might not be detailed for special cases.
All gas circuit breaker 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 gas circuit breaker that is under the construction process is:
The applicable codes and standards may be based on any international standards. This content is general and can be useful for all recognized standards.
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:
The first actual inspection work in the gas circuit breaker 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:
Then the inspector witnesses the materials identification on the certificates against the materials marking. It is also necessary to check these with the gas circuit breaker 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:
When the gas circuit breaker raw material inspection is carried out, and the results were satisfactory or non-conformities were closed by remedial action, then the gas circuit breaker manufacturer will start fabrication.
The third party inspector checks the following points on the gas circuit breaker, based on the inspection and test plan (ITP), which has already been agreed upon between the purchaser and the gas circuit breaker 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 following items in Gas Circuit Breaker construction process:
It is necessary the results meet drawings and applicable standards
The third party inspector checks that all instruments, control switches, interlocks etc. are correctly rated and are correctly located, with specified labelling in accordance of approved drawings.
Air pressure is raised until the safety valve operates and this pressure is applied to all parts of the system and blow out pressure need not be more than specified value
Systems containing gas under pressure is given leakage test to ensure against gas leakage at joints and it is necessary the result to be within specified value.
The third party inspector checks the operation of air pressure switch and the number of close, open operations; starting at normal working pressure without replenishing the air in the air reservoir.
The test would be acceptable is the abnormality not occurs during the test.
The test is made on complete circuit. Test voltage, frequency and applied time must comply with the standard, code and/or specification.
All circuits of auxiliary and control circuit are subjected to the specified voltage for one minute. The test voltage is 1500V or 2000V, frequency 50HZ or 60HZ and applied time – 60 seconds.
The test would be acceptable if the circuit withstood to meet requirement.
The resistance of each pole of the main circuit is measured within factory limitation.
The adjustment and operation over the entire range of control voltage and specified operating pressure is controlled. The test is done in following conditions:
The time required for breakers or components to operate on open, close, close-open and reclosing operation are checked and test would be acceptable if no abnormality occurs during the test.
Air compressor unit is operated electrically and its operation checked and would be acceptable if no abnormality occurs during the test.
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 gas circuit breaker 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 gas circuit breaker.
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 gas circuit breakers have been accepted.
The following points are checked by the third party inspector:
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