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Transformers Testing:

We offer highly effective Transformer Testing, which is very important for an efficient working of the transformer and its reliability. High performance and durability of Transformers can be achieved by using superior quality raw materials and technically advanced machines thus ensuring high standards of workmanship during production. Our company carries-out various tests at different stages of manufacturing process. The final tests on fully assembled transformer also assure suitability of the equipment for satisfactory performance. Our tests are conducted as per norms of IS2026/1EC726/BS171 to ensure reliable and efficient performance of the transformer during its lifetime.

After finalization of the erection work the following tests should be conducted:

  • Measurement of winding resistance
  • Verification of voltage ratio
  • Verification of vector group
  • Measurement of no load current and losses
  • Measurement of impedance and load losses
  • Measurement of insulation resistance
  • Power frequencies withstand voltage
  • Induced over voltage test
  • Air presser test
Type Tests
  • Impulse voltage withstand test
  • Temperature rise test
Ratio, Polarity and Phase Relationship:

The ratio should be checked at all taps and between all the windings. It is checked by applying a single-phase 230V (approx) supply on the high voltage side and measuring the voltage on the low voltage side at all tap positions. The measured voltage on LV side shall conform to declining trend between tap (min) to tap (max) position for all phases. Polarity and interphone connections are checked while measuring the ratio. This can be checked by the avometer method. The primary and secondary windings are connected together at points indicated in sketch shown below. A low voltage three-phase supply is then applied to the HV terminals. Readings obtained should be the vectorial sum of the separate voltages of each winding under consideration.

Bangalore based reputed manufacturers, supplier and service provider of a wide selection of excellent quality Resin cast Transformers, Special type Transformers, Power Transformers, Dry type Transformers, air-cooled transformers, furnace transformers and Distribution Transformers Manufacturers etc...!!!


  • Our Team
  • Quality Policy
  • Technology Expertise
vijayvijayWe, VIJAY TRAFO have a team of qualified and experienced professionals who have expertise in this field. Our team consists of quality controllers, research and development division, designing & manufacturing engineers, HR and electrical engineers. Additionally, our team is also involved in commissioning and testing Transformers. Our team is capable enough to meet every need of clients at affordable prices.
Being a quality and customer centric company, we give more importance to quality. Hence, all power distribution Transformer and Transformer Accessories at VIJAY TRAFO are engineered using the highest grade of raw materials under the supervision of highly qualified engineers and technicians and well-experienced workingmen to comply these products & services with international quality standards. Our tough quality control practices are the key behind our success.
We have highly advanced manufacturing unit, which is well equipped with latest tools and testing facilities. We have modern facilities to manufacture technically advanced Transformers up to 10000 KVA, 33KV class for indoor & outdoor applications. Professionals at VIJAY TRAFO always make strong efforts to upgrade our R&D work and make all necessary modifications according to market trend.

Pre Test Inspection

  • Sample of oil taken from the transformer and subjected to electric test (break down value) of 50KV (RMS) as specified in IS: 335.
  • Release trapped air through air release plugs and valve fitted for the purpose on various fittings like radiators, bushing caps, tank cover, Bushing turrets etc.
  • The float lever of the magnetic oil level indicator (if provided) should be moved up and down between the end positions to check that the mechanism does not stick at any point. If the indicator has signaling contact they should be checked at the same time for correct operation. Checking the gauge by draining oil is a more positive test.
  • Check whether gas operated (if provided) is mounted at angle by placing a spirit level on the top of the relay. Check whether the conservator is filled upto the filling oil level marked on plain oil gauge side and corresponding to the pointer reading in MOG side. Check the operation of the alarm and trip contacts of the relay independently by injecting air through the top cocks using a dry air bottle. The air should be released after the tests. Make sure that transformer oil runs through pert cock of buchholz relay.
  • Check alarm and trip contacts of WTIs, dial type thermometer, magnetic oil gauge etc. (if provided).
  • Ensure that off circuit switch handle is locked at the desired tap position with padlock.
  • Make sure that all valves except drain, filter and sampling valves are opened (Such as radiator valves, valves on the buchholz relay pipe line if provided).
  • Check the condition of silica gel in the breather to ensure that it is active and colour is blue. Also check that the transformer oil is filled in the silica gel breather upto the level indicated.
  • Check tightness of external electrical connections to bushings.
  • Give a physical check on all bushing for any crack or any breakage of porcelain. Bushing with cracks or any other defects should be immediately replaced.
  • Check the neutral earthing if specified. Make sure that neutrals of HV I LV are effectively earthed.
  • Tank should be effectively earthed at two points.
  • Check that the thermometer pockets on tank cover are filled with oil.
  • If the oil temperature indicator is not working satisfactorily, loosen and remove the thermometer bulb from the pocket on the cover and place it with a standard

Transformers Testing