5 Challenges to overcome for testing Tan delta of Transformer Oil

Transformer oil testing is the lifesaver of a transformer. From dissolved gas analysis to furan testing to tan delta and resistivity testing, transformer oil has a lot to say about the longevity of the transformer. It helps to detect the level of major enemies of transformer oil like oxidation, and contamination. One way to detect such changes is by performing tan delta and resistivity tests of transformer oil. Tan delta or dissipation factor or power factor tests indicate the margin by which the oil has lost its insulating properties. Once the margin crosses a set threshold limit, the insulating oil is no longer fit to use for the transformer. Resistivity tests also indicate the state of the electrical property of the oil. As a test engineer working closely with the maintenance team, carrying out these two tests regularly, is a must. Typically these tests need to be performed every six months to monitor the health of the transformer oil. Execution of these tests, however, is not an easy task. There are quite a few challenges which a test engineer may face while carrying out the test. Here is a list of 5 challenges along with a potent solution for each of them:

From dissolved gas analysis to furan testing to tan delta and resistivity testing, transformer oil has a lot to say about the longevity of the transformer.

Preparing a Manual Report

One of the tedious tasks associated with these tests is to keep a log of all the measured values, dates, and other vital information in an organized and accessible way. For long, companies have been relying on manual reports that are unorganized and stored locally. With advanced technologies like USB, Bluetooth and Cloud connectivity, modern test kits offer remote accessibility and automatic generation of reports. Here the values can be exported from the kit to a mobile device via apps or Bluetooth and the reports are generated online. Every record is maintained in such a way that it is easier to analyze the results. In turn, it improves overall productivity and saves time and money.

Oil spill

One major issue that engineers face is the oil spillage which may occur while draining the sample liquid to or from the beaker. The oil spills not only create a mess but also are a deterrent to the performance of the kit as it leads to incomplete cleaning of cells. It may alter the properties of the oil due to prolonged light exposure. Sampling and improper handling can also contaminate the oil which may lead to inaccurate results. To avoid this, a test kit with an automatic drain feature is preferred. This feature automatically drains the oil once the test is completed. So there will be no chances of the oil spill, and the equipment remain clean at all times. 

  • Portability and Logistics: As transformer oil needs to be tested at high temperature for accurate results, it requires a heating chamber, Most of the tan delta oil testing equipment come in a double test equipment model, where the heating chamber is placed separately. It makes the equipment bulky. Modern tan delta oil kits come with an inbuilt heating chamber. This design condenses the two-unit test kit into one. Some kits come with a transportation case as well, which improves the overall portability of the kit, and aids in easy logistics.
  • Reliability and Accuracy: Since high-temperature tan delta tests are more sensitive to small changes, transformer oil is heated to a temperature in compliance with IEC 60247 standards. However, most of the oil kits do not follow the standards and have a higher probability of producing inaccurate results. It leaves the engineers in total ambiguity and leads to disastrous decision-making. Therefore, a kit must comply with basic standards like IEC 60247 for the results to be accurate. Modern test kits offer uniformity of temperature throughout the sample, which ensures reliable results.
  • Multi-parameter oil test kits: Tan delta testing gives a broad picture of the electrical properties of the oil. However, another testing of other parameters like resistivity is of equal importance. A tan delta testing it with multi-parameter testing features makes it easier for the test engineer to create a report and analyze the oil properties. 

The transformer oil tan delta test equipment from many leading manufacturers are designed specifically to overcome these challenges and maximize productivity. Their designs are specifically compliant with the IEC 60247 standards and comes with a microcontroller based inbuilt heating chamber.

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