Transformer Testing

We are having following Testing Facility for Transformer

  • Dielectric Response Analyzer (DIRANA) Test
  • SFRA Test (Make: Doble)
  • Tan Delta Test (Make: Megger)
  • High Voltage Test
  • Insulation Resistance Test
  • Winding Resistance Test (Scope)
  • Voltage Ratio Test
  • Measuring Open Circuit Voltage
  • Measurement S C Current Test
  • OTI and WTI Calibration
  • Magnetic Balance Test
  • Spill Current Test
  • DVDF Test
  • BDV Test of Transformer Oil
  • Impedance Voltage Test
  • Vector Group Test
  • Earth Resistance Test
  • CT Testing (Knee point Voltage Test & Primary Injection)
  • Due Point Test (Doble Make Kit)
  • Moisture Content in Oil(PPM) (Doble Make Kit)
  • Moisture Content in SF6 Gas (Doble Make Kit)
  • CT ,PT & Power Analyzer for Loss Measurement(Yokohama)

  • Dielectric Response Analyzer(DIRANA)Test

    Dielectric Response Analyzer (DIRANA) Test on Transformer Winding (To determine the moisture content in oil-paper insulations of Winding by Direct Measurement). This is the most advanced method of determining the moisture content in oil-paper insulations of Transformer Winding. The DIRANA reduces the required measurement time to 50%, as the device uses a combination of the time and frequency range method (Polarization Depolarization Current [PDC] and Frequency Domain Spectroscopy [FDS]).


  • Water analysis of oil-paper insulation
  • Capacitance and dissipation factor measurement on power transformers
  • Dissipation factor measurement and determination of ageing on bushings
  • Diagnosis of generator, motor and cable insulation, as well as instrument transformers
  • Key Features

  • Extremely fast measurements reduce downtimes
  • Detailed connection diagrams show the correct wiring for various measurement scenarios
  • Automatic determination of the water content with the DIRANA software (no expert knowledge required)
  • Reliable moisture content determination for new and aged oil-paper insulation
  • No overestimation of water content due to unique compensation for ageing by products
  • Evaluation of very dry transformers due to a wide measuring range of 5 kHz to 10 µHz

  • SFRA Test ( Sweep Frequency Response Analysis )

    Doble Make SFRA Test Kit:

    Region Frequency Sub-Band Components
    1 < 10 kHz Main Core; Bulk Winding (Inductance)
    2 10 kHz to 150 kHz Bulk Component Shunt Impedances
    3 150 kHz to 400 kHz Main Windings
    4 400 kHz to ~1 MHz Main windings, Tap windings etc


    In This Test Insulation power factor or dissipation factor (Tan delta) and Capacitance measurement of bushing provide an indication of the quality and soundness of the transformer winding/winding of alternator motor and insulation in the bushing. In this Test voltage upto 10kV is applied to Bushing and Winding. There are two type mode of measured in this method UST & GST Mode.

    Eltel Make Tan-delta Testing Kit

    In this test, voltage upto 10kV is Applied to Bushing and Winding.There are Two type mode of measured in this method UST & GST Mode.

    Insulation Resistance Test(5000 Volts)

    Insulation resistance (IR) measurement is the simplest and most widely used test to check the soundness of transformer insulation. This test reveals the condition of insulation (i.e.Degree of dryness of paper insulation), presence of any foreign contaminants in oil and also any gross defect inside the transformer (like failure to remove the temporary transportation bracket on the live portion of tap-changer part).

    Winding Resistance Test (25 amps)

    Transformer winding resistance are measured in the field in order to check for any abnormalities due to loose connections, broken strands and high contact resistance in tap changers as a pre-commissioning checks and compare the measured values with factory test values.

    Voltage Ratio Test

    To determine the turns ratio of transformer, Turns Ratio: The Turns Ratio of a transformer is the ratio of the number of turns in a higher voltage winding to that in a lower voltage winding. Transformer turns ratio (TTR) meter available in convenient portable form. They have a hand crank power supply, with the voltages commonly used being very low, such as 12-120 V and 50-60 Hz.


    There is need for testing and monitoring the electrical network’s arresters, in order to verify their good condition and their ability to effectively protect the lines. The most common method used, is the measurement of the arresters’ total leakage current (with the isolation of the resistive part), which is an indicator of the arrester’s condition, since every change, deterioration or damage leads to an increase of the resistive leakage current.


    VLF cable testing is a technique for testing of medium and high voltage (MV and HV) cables. VLF systems are advantageous in that they can be manufactured to be small and lightweight; making them useful – especially for field testing where transport and space can be issues. Traditionally DC voltage sources have been used for field testing of cables but these sources have been shown to be ineffective at withstand testing for most kinds of damage. DC diagnostics have also been shown to yield ambiguous results and are generally considered and ineffective for MV and HV power cables. Because the inherent capacitance of a power cable needs to be charged when energized.