The fundamental objective of electrical testing is that the results and measurements derived from this process are accurate and can be relied upon. Unfortunately, test instruments are often used in conditions which can affect this, or are subjected to general wear and tear or damage in the course of their everyday work. This can all cause a drift in readings, and because the output from test instruments is critical in making key decisions, it is important that an instrument can be relied upon at all times, and calibration is the process through which we can achieve this.
So calibration is the process of removing an instrument from everyday use and going through a series of checks to verify its accuracy against known standards. We can verify the accuracy of an instrument by confirming these readings fall within acceptable tolerances, and if they don’t we can make adjustments to ensure they do. It is usually the case that an instrument won’t be released back into general use until its readings fall within the tolerances dictated by the relevant standards.
The importance of calibration with test instruments
Test instruments are used in electrical testing to provide readings and measurements which are used to verify conformity, confirm a safe installation and to diagnose problems. These are critical readings for the safety of an electrical system, and therefore inaccurate readings could have significant impacts on the safety of people, buildings and equipment. It is common for test instruments to experience a drift in readings from everyday use, and these are not always noticeable. So calibration is important in order that we comply with external regulations, and so that we can confirm our readings are always accurate and decisions and judgements can be made which won’t compromise the safety of electrical installations.
The details of a calibration service
The process of a calibration service will usually include:
- Maintaining an itinerary of test instruments, including marking each one with a unique reference code, identifying its location and keeping documents on each instrument.
- Deciding on a frequency of calibration for each instrument, based on factors such as the manufacturer’s recommendations, compliance requirements, how often the instrument is used, the environment in which the instrument is used, how the instrument is stored and how critical the readings are in terms of voltage levels or safety factors.
- Maintaining a record of when calibration is next due, and creating a robust notification system so that calibration dates are not missed.
- Establish the accuracy tolerances required for calibration checks, usually based on manufacturer recommendations or regulatory standards.
- Visually inspect the instrument for signs of damage and clean and service the instrument.
- Test the instrument at multiple points within a range to verify the accuracy of its readings.
- Verify whether the instrument is reading in or out of these tolerances.
- Record the results along with the date of calibration and the pass/fail confirmation.
- Where an instrument has failed calibration, a list of remedial actions shall be drawn up.
- When the instrument has passed calibration it can be released back into general use and records updated to document this.
Test Instrument Solutions has an accredited calibration service and we are able to calibrate your test instruments and manage your calibration programme, incorporating all the actions outlined above. We have a computerised recall service which ensures your instruments don’t fall out of calibration and you receive sufficient notice to manage your processes without these instruments. We can carry out calibration days on your site, or at a distributor site, at your convenience.
Please note that this section is for information purposes only. Anyone using equipment referred to in this section must be suitably qualified and/or experienced within the respective field. If in doubt before use, please consult a qualified electrician or engineer & thoroughly read all instruction booklets.