IEEE STD C57.12.90 PDF

3 Park Avenue. New York, NY USA. IEEE Power and Energy Society. IEEE Std C™/Cor (Corrigendum to. The definition of constant k in Equation 2 (in ) and line terminal rated voltage in the last paragraph of are corrected in this corrigendum. Define IEEE Standard C means the IEEE Standard Test Code for Liquid – Immersed Distribution, Power, and Regulating Transformers, ;.

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Grounding through a low-impedance shunt for current measurements may be considered the equivalent of a solid ground. The time to sparkover for front-of-wave impulse tests shall be the time from virtual zero to the time of sparkover.

NOTE 2—In some cases, tests at the required full-wave impulse level with the standardized lightning impulse wave shape will not show the operation of the nonlinear devices. For the common winding resistance, the current shall be circulated between the high-voltage and neutral terminals, and the voltage shall be measured between the low-voltage and neutral terminals.

In order to achieve core saturation in a short time period, the dc power supply voltage should be large enough to saturate the cores in a short time. Phase-relation tests are made to determine angular displacement and relative phase sequence. Measurement of voltage and current induced in another winding may also be used for failure detection. Each reduced full-wave test performed after a full-wave test shall be compared with the corresponding reduced full-wave test performed prior to the full-wave tests.

For single-phase transformers, the three-phase bank power rating and associated phase-to-phase voltage should be used in the above equation. The time constant of a container shall be taken as the time necessary for its temperature to change 6.

A room with a solid floor and an undetermined amount of sound-absorbing materials on the walls and ceiling. If instrument transformers are required as is generally the casethen Figure 17 applies.

Infrared measurement devices may also be used to measure surface temperatures.

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Definition of IEEE Standard C57.12.90

Tests on other taps, or connections in the case of c57.12.0 voltage windings, may be required to verify design adequacy. IEEE does not, by the publication of its standards, intend to urge action that is not in compliance with applicable laws, and these documents may not be construed as doing so.

Circuits or groups of circuits of different voltage above ground shall be tested separately. The extended arc length of the rod- rod gap provides more natural circuit damping than the shorter arc length of a sphere gap.

Factors that cause differences in the no-load losses of transformers of the same design include variability in characteristics of the core steel, mechanical stresses induced in manufacturing, variation in gap structure, and core joints.

The dielectric tests should be performed in the preferred sequence as follows: Insulation resistance tests are made to determine the insulation resistance from individual windings to ground or between individual windings. NOTE 1—Measurement of ratio using circuits of this type has also been described as ratio by resistance potentiometer. Ueee 2 is valid only for test voltages with moderate waveform distortion.

The voltage shall be measured with a voltmeter responsive to the average value of the voltage but scaled to read the rms value of a sinusoidal iese having the same average value. The post-set method does not demonstrate syd the transformer would be able to withstand energizing the transformer on a short-circuit, i.

Compensation for instrument errors by an interchange of instruments will otherwise not be satisfactory, and it will be necessary to apply appropriate corrections to the voltmeter readings.

A thermocouple is the preferred method of measuring surface temperature. This voltage shall be V plus 3. The input or output terminals are shorted, and voltage at rated frequency is applied to the other terminals. Table 2 —Maximum test duration Test voltage as a percentage of Allowable duration maximum system operating voltages min 5 12 36 When inducing a transformer in excess of its rated voltage, the test frequency should be increased as necessary to avoid core saturation.

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Show the position of the transformer with respect to other objects, and show the location of the measuring surface, the microphone positions, and sound reflecting or absorbing surfaces. If external neutral is not available, the phase should be shorted to ground.

IEEE Standard C | legal definition of IEEE Standard C by

If surface temperature measurements are made on radiator headers, choose headers one third or one half the way in from either end of a bank of radiators. As an exception to the test sequence given in The averages of the results are the correct voltages. Hot-resistance measurements shall be taken as soon as possible after shutdown, allowing sufficient time for the inductive effects to disappear as indicated from the cold-resistance measurement.

The quantity a for the calculation of the per-unit regulation of a two-winding transformer is determined by Equation Under those conditions, the correction, described in For example, in Figure 5, the voltmeter lead connected to H1 will be transferred to X 2 as the adjacent c5.712.90, and the lead connected to H 2 transferred to X 1.

For dated references, only the edition cited applies.

IEEE Standards documents are not intended to ensure safety, security, health, or environmental protection, or ensure against interference with or from other devices or networks. NOTE c57.21.90 factory power-factor test will be of value for comparison with field power-factor measurements to assess the probable condition of the insulation. When the liquid time constant of the transformer under test is more than 2 h, the time constant of the containers shall be within 1 h of the liquid time constant of the transformer leee test.

The reported final test data shall include the measured sound levels along with the corrections used in sgd the final value s. Since the sound-intensity measuring method allows measurement of only the sound radiating from the transformer, these corrections need not be made.