Intelligent Condition Monitoring of Transformers – You are in Need
Power transformers are one of the most expensive elements and play a critical role in the transmission of power in electric grid and in extreme cases a failure may result in their destruction. Electricity availability is critical in the development of any country.
As transformers age, their internal condition degrades, which increases the risk of failure. To prevent these failures and to maintain transformers in good operating condition is a very important issue for utilities.
During operation, power transformers are subjected to various stresses including thermal and electrical, resulting in liberation of gases from the hydrocarbon mineral oil which is used as insulant and coolant. If not monitored, these abnormalities will deteriorate transformer windings and produce incipient faults that go unnoticed.
A transformer oil carries information about the condition of the transformer. Analyzing the oil in service can therefore give early warnings about inner problems. We can imagine that a transformer is like a human being, where the oil within is equivalent to our human blood. Just like using blood tests to determine human health condition, the oil is tested to give an indication of conditions inside the transformer. Different types of faults generate different gasses, the analysis of these gasses will provide useful information about the condition of the transformer.
The dissolved gas analysis (DGA) is one of the most important used diagnostic method to assess the status of a transformer. Which is used to detect single or multiple gases dissolved in transformer oil, is the first choice and will cover about half of the most probable failures. A proper analysis will help identify the real cause of the gas generation and thereby locate the criticality for maintenance or replacement.
There is an increasing need for better diagnostic and monitoring tools to assess the internal condition of the transformers. If there is a problem, the transformer can then be repaired or replaced before it fails. The cost of a power transformer is high, but monitoring the performance of the transformer is inexpensive compared to the cost of a failure in a transformer and the costs of an interruption in power supplies. Condition monitoring is a powerful and reliable diagnostic tool to protect large, expensive transformers and can be applied at a reasonable cost to all sizes and types of oil insulated transformers.
With intelligent condition monitoring, diagnosis and maintenance, transformers can continue to provide reliable service far beyond the average transformer life expectancy. It justifies the need for the detection and identification of failures at their early stage to implement preventive actions. If the transformer is monitored continuously, it is possible to define maintenance actions based on the condition of asset.
To assess the condition of transformers while in continue operation, which would normally involve collecting data / operational parameters, visual inspections, DGA and preferably online DGA monitoring, some other basic important oil tests as moisture contents and BDV (break down Voltage) etc. When necessary as per condition monitoring assessment, the oil samples can be taken for other testing from a certified laboratory.
As the transformers are most important and critical assets in electrical power systems. Therefore, it is vital to monitor and diagnose transformers continuously, not only to minimize damages associated with any defect of the transformer, but also to achieve a more efficient management of its life cycle.