Transformer is a sophisticated device, an assembly of many components that perform different functions. Winding insulation bushings, cooling medium, fault detectors, and safety devices are all crucial components of transformers. Each of them needs to be in good working order so that safety and performance are assured. Given the continuously high performance of power transformers over a long period without a break, these transformers require robust maintenance services.
Power transformer testing is an essential part of the maintenance of transformers. Servokon provides these services to ensure the safe and reliable performance of the various parts of the power transformer. In this guide, we will learn about the key tests performed on power transformers.
Pre Testing Preparations
Before testing procedures begin, it is important to ensure safety of the technicians as well as avoid bigger faults. The transformer is completely de-energized, i.e., disconnected from the electrical grid, neutral and ground connections. No potential difference and no electrical current is flowing through it. Connection points are cleaned for taking accurate readings.
Overview of Power Transformer Testing
- Inspections – In the visual inspection, the oil leakages, physical damage, wear, and moisture condensation are checked. The gauges of oil level, temperature, and pressure/vacuum are monitored. Painting and rust conditions are assessed.
- Insulation Resistance – The Megger test is the key to testing the insulation resistance of the transformer. It involves the measurement of readings between windings, between the winding and the ground. Polarisation index is calculated, and other detailed analyses are conducted to check for degradation or contamination in the insulating medium.
- Winding Resistance – The winding resistance test measures the DC resistance of the windings to verify the internal connections and contact with the tap changer. If a change in resistance is detected, it means there is some fault in development. Both winding and insulation resistance are electrical tests. Other such tests include turns ratio, open circuit, and vector group check.
- Dielectric Tests – This is a diagnostic test which is performed to insulating properties of the oil. Dielectric strength, dissolved gases, and moisture content are checked, which tells the condition of the oil. Some other diagnostic tests are Sweep Frequency Response Analysis (SFRA) and Power Factor Testing.
- Specific Tests – Partial-discharge test, impulse tests and heat run tests are specific to the power transformers. Zero-Sequence Impedance is performed on the three-phase transformers to check data on protective relays.
Conclusion
When buying any transformer, it is important to choose a reliable power transformer supplier that offers maintenance and repair services. Servokon System Limited is a trusted manufacturer and supplier with a huge clientele that features some of the most reputable names such as ISRO, Reliance, Aditya Birla Group, Tata and DLF. From banking to real estate to large scale businesses, we are serving all with our comprehensive support services related to transformers.
