Monitoring transformers for good health

Transformer system in itself is a very complex system and it requires continuous monitoring and maintenance. However in spite of that there are transformer failures generally are seen in India (95 per cent of them in rural areas). Saurabh Pataria , CEO, National Electrical Equipments Corporation highlights the following reasons:

• Power theft, causing overloading and hence failure of transformers
• Oil theft in remote areas cause transformers’ cooling to stop and hence failure
• Transformer’s parts’ theft are also common because of the costly items like brass, copper and aluminium used
• Failure also occurs due to degradation of the insulation material due to overloading of the transformers
• Poor maintenance at site is also a reason for failure of transformers; it may be due to mishandling, breakage of parts of the transformers, falling from the pole, not monitoring the leakage etc
• Single phasing problems is also very common in rural areas which causes even big transformers to fail

The rate of failure of distribution transformers are too high, as the power utilities are not maintained as per the recommendations prescribed by the manufacturers. We have witnessed at several occasions and have been reading in the news about transformers explosion resulting into oil leakage on the exterior of the transformer and causing physical injuries to people around. Following the same, Parag Yelegaonkar, Business Development Manager, Government Business, Testo India Pvt. Ltd. says, “Some of the power distribution companies have quoted for purchasing bulk thermal imagers for detecting such loose ends in the transformers. It’s a progress that the distribution companies have started realising the significance of thermal imagers.”

Transformer Monitoring System for a distribution transformer

Generally, transformer monitoring systems are used in bigger transformers above 500KVA in general. For smaller transformers, it is up to the buyer and the site whether there is requirement for TMS or not. For monitoring purpose in transformer, Pataria says, “Most importantly, we need to monitor oil level, temperature of oil and winding, noise and loading. By monitoring them we can evaluate the situation of the transformer.”

TMS comes in two types, one is just visual type where person has to observe at site and other types are microcontroller-based sensor type which delivers the situation at the control room. Both are efficient and all electricity boards in India uses different types depending on where the substation is being put up. Hence, in Pataria’s words, “The role of TMS is very important and generally it is used for substation transformers from where all small transformers of that particular area are connected in line and it plays a very important role in nearly negating the chances of failure by raising the alarm in case of any problem.”

Power transformer is an essential asset of any utility company. In a power transformer, bushing inspection is critically important. Yelegaonkar says, “Our testing and measurements is a portable monitoring system, which is used to inspect these power transformers and save them for bushing from catastrophic attack or fire.“ Every power transformer must be inspected once in a month including the transformer radiator, transformer bushing, transformer junction box, transformer LT side and HT side terminations and the transformer body to check if there are any thermal anomalies. In the process, if any thermal anomalies are detected these imagers will help in taking appropriate actions. During a shutdown you can open the transformer radiator and clean the radiator fins. “We also need to check whether there’s oil leakage in bushing, and that there are no loose or corroded connection in the bushing,” says Yelegaonkar.

The success rate of TMS

Yelegaonkar rates transformer monitoring as a very important aspect, as it covers human safety also. If anything goes wrong in the transformers like oil leakage or internal explosion in the transformer system, it will further harm human life.

According to Pataria, the success rate of TMS is almost 100 per cent, unless there is a problem in the monitoring equipment (again that is rare) or ignorance in detection (for which also chances are negligible). Hence, it is always advisable to use TMS to keep the transformer working at good health. Generally, transformer life is more than 15-20 years, unless there is augmentation in load in that area, hence TMS is like doctor for a transformer who keeps it under monitor for its good health. One grid failure can lead to darkness in huge area so keep the doctor handy.

Power distribution companies have quoted for purchasing bulk thermal imagers for detecting loose ends in the transformers.
Parag Yelegaonkar, Business Development Manager, Government Business, Testo India Pvt Ltd

Transformer Monitoring System is like doctor for a transformer who keeps it under monitoring to keep a check on its health.
Saurabh Pataria , CEO,  National Electrical Equipments Corporation