IEEE C57.12.58-1991 pdf download.IEEE Guide for Conducting a Transient Voltage Analysis of a Dry-Type Transformer Coil.
Published Date:1991-6-27 Reaffirmed:2002-06-12
Abstract:General recommendations for measuring voltage transients in dry-type distribution and power transformer are provided. Recurrent surge voltage generator circuitry, instrumentation, test sample, test point location, mounting the test coil, conducting the test, and reporting results are covered.
Since the fumction of transient analysis is to determine the response of various paris of the coil to an impulse wave, the circuitry and instrumentation must be designed with that goal in mind. From a functional point of view, the relationship between the test specimen ciruitry, and instrumentation may be seen best in the form of a block diagram as shown in Fig 1.
1.2 Recurrent Surge Generator
The voltage-generation and wave-shaping functions are pertormed by a device called a recurrent surge generator. This generator must duplicate, at some voltage compatible with low-voltage instrumentation, the wave shapes seen at the u put of an impulse generator. The surge generator, since it is operating at a low voltage, may generate the wave on a recurrent basis. In fact, observation of voltages on an oscilloscope face will be facilitated if the voltage wavc is recurrent.
1.3 Voltage Measurement
The voltage is applied across the test coil at the [mc terminals. Voltages hetwecn various points within the coil are measured with a high- frcqucncy oscilloscope or other device using a differential amplifier and probes at the input. It is highly dcsirable that there be synchronization between the generator and the recording instrumentation. This may be accomplished by either a delay in the signal or triggering in advance of the wave. This will ensure the establishment of a zero reference point at the readout. Digital cquipmern may offer other synchronization methods.
2. Recurrent Surge Voltage Generator Circuitry
2.1 Description of the Circuit
The circuitry is shown in Fig 2 in its simplest form to provide the timnction of voltage generation and wave shaping. The voltage is ohtaintxl Irom an ac source and is transformed to a desired level through a variable auto transf’ormer and isobtion translrnner. Only the isolation transfirmner is shown in Fig 2. The peak output voltage is limited by the voltage capability of the intrumcmnation and by ratings of the resistors and capacitors in the wave-shaping portion of the circuitry the most pracucai range is between 50 and 150 V. the higher the voltage, the higher the accuracy [he repetition rate of the wave may be the ac power liequcticy.IEEE C57.12.58-1991 pdf download.