Article courtesy of Master Calibrators Australia;
One of the more common questions that we get asked in regards to Calibration and HV Testing is how to interpret the reports and certificates issued. Reporting is perhaps equally as important as the actual testing or calibration procedure. It isn’t just a legal requirement, but good work practice and as such, should be something that you, the user, should have an understanding of.
Everything you need to know about the condition of your equipment will be displayed on this report. This article will do its best to explain what it is that you are looking at on reports, and what it means.
These have the most information and can be the hardest to digest. The front cover provides a great deal of information about the calibration company, the instrument owner, the equipment used during the calibration, and much more.
Starting at the top of the certificate, there must be a title, the name of the organization performing the calibration, which issued this certificate, and the date of issue. There must also be be a unique certificate number, issued by the calibration company.
Under this information will be contact information for the calibration company. The name and contact details must be unambiguously clear. Next to this will be the approved signatory. Usually this will be the technician that carried out the calibration and is the individual that is authorizing the calibration certificate.
Customer details and instrument description will be next in line. Customer details should include name and address and the instrument description must include make, model and serial number. Environment conditions are self-explanatory, these are the temperature and humidity conditions that the meter was calibrated under. Directly under environmental conditions, will be a comment section. This is where the technician will make any comments that are relevant to the meter being calibrated.
Moving to the bottom of the front page now, and at this point, we are listing the Traceability information. Traceability is the unbroken record of documentation. A client’s meter will of course be tested by a calibrator (or standard) and that calibrator (or standard) will need to be calibrated by another Standard and so forth. For each calibration, there must be documentation. This line of documents makes up Traceability. On calibration reports, it will be the Test Standard that was used to calibrate the clients meter. It must list the serial number, certificate number, date calibrated and the calibration period between calibrations. All this information can be presented at a moments notice if required.
The final piece of information on the front page will be the name of the technician and date that the calibration was carried out as well as a disclaimer at the bottom that highlights that the certificate complies with. We recommend a minimum of ISO10012:2003, ISO17205:2005 and ISO9001:2008.
The following pages will display the actual test results. The test results fall under 5 headings. Test Title, Tolerance, Applied Value, Reading, and Pass / Fail.
- Test Title will be the title of the test. This is usually the Range of the meter that is being tested.
- Tolerance is a value that the meter is allowed to be within. This is calculated by the calibration software and is based on the specifications outlined by the meters manufacturer.
- Applied Value is the test value that is being applied to the meter under test.
- Reading is the value that the meter under test is displaying.
- Final heading is Pass / Fail. This is an overall result for that test. It has either Passed or it has Failed, based on weather the Reading, was within the specific Tolerance, of the Applied Value.
There should always be a variety of tests, conducted on each meter function and range. A reputable calibration certificate will never have only or two tests per function. This is not correctly or accurately confirming that the meter is functioning correctly and reading accurately across it’s full range. Depending on the type of function and range, you should see at least three to five tests on each function and range.
At the bottom of the Test Result pages will be the uncertainties of the calibrator’s applied values. It is important to mention here, that everything has uncertainty. For example, when you lift your arm to check the time on your watch, there is a certain amount of uncertainty that the time you are looking at is in fact the correct time. It might be 1 millisecond either way. Whenever there is an aspect of measurement involved, there will be a certain amount of uncertainty.
Equipment Test reports are a bit easier to follow, as there is less information to digest. Starting at the top of the report will be the Title as well as the Testing Company’s contact details.
There will also be a note referencing the National Standard or any relevant document/s that the equipment is being tested to. The exception is when one test report contains various tests, all conducted to different standards. When this is the case, the reference standard may be listed on the test line. This approach is often taken for HV Testing of Safety Equipment or inspection of Rigging and Lifting Equipment because there are a very large variety of Standards / Documents that could be referenced for Electrical Safety Equipment. For other equipment, such as EWP’s or Height Safety Equipment, there are one or two overarching Standards that cover the testing procedure. For Electrical Safety Equipment, the number of Standards used and referenced is much higher.
Next on the report will be the details of the client. This will include name, address, contact details, date tested, date due and a unique Job Number. Any comments are also be added here. Equipment Traceability will be listed directly under the client’s details. This is the information of the equipment the Tester has used to test the equipment.
The remainder of the test report will be the actual test results. This will include but not limited to Asset ID, Item Description, Visual inspection, Test Voltage in kV, leakage results in mA and an overall Pass / Fail result.
- Asset ID is an individual and unique identifying ID number (or name) assigned to that item, and that item only. It allows test results to be tied back to a particular item.
- Item Description gives a brief description of the item being tested. It should be descriptive and use commonly accepted industry terminology.
- Visual inspection field is a simple yes or no option. If the item is in good working order visually, this will receive a tick. It is visually unfit or unsafe for use, no tick will be given and the item will fail on visual grounds. No further electrical test are performed.
- Test Voltage in kV shows the Test Voltage that is applied to Electrical Safety Equipment during the electrical test. This is usually as defined by the Standard, however sometimes best practice or client requirements dictate a higher test voltage. Be very careful if you are using a testing service provider who does not put a test voltage – they may not be performing an electrical test at all and purely performing a visual inspection.
- Leakage Results in mA are given as a means of measuring the level of insulation provided by the item, and to a lesser extent for monitoring equipment degradation over time. Again, we urge you to be very careful if you are using a testing service provider who does put a leakage current – they may not be performing an electrical test at all and purely performing a visual inspection.
- Pass / Fail result in most cases is based on whether the piece of equipment under test withstood the test voltage for the test period. If it withstood the test without a puncture, it will Pass. For some items, even if it has withstood the test and not punctured, but the leakage reading is above acceptable limits (taken from the applicable Standard) it may also be deemed as a Fail.
All Test Reports must be finalized with the name and signature of the trained technician who conducted the testing