IEEE STD C57.12.90 PDF

August 18, 2019 posted by

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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The standard reference temperature Tr for transformer no-load losses is specified in 5.

Definition of IEEE Standard C57.12.90

The reported final test data shall include the measured sound levels along with the corrections used in determining the final value s. If performed, however, it may be used as a check. For three-phase transformers, Figure 18 shows the apparatus and connections using the three-wattmeter method. A room with a solid floor and an undetermined amount of sound-absorbing materials on the walls and ceiling.

When performing winding resistance measurements on a transformer that utilizes series transformers for load tap changing, care is required to increase the likelihood that the whole circuit, consisting of the main and series transformer windings, is saturated before stable readings of the combined winding resistances can be obtained.

The tank, the core, and either one of the low-voltage terminals or the neutral terminal are also connected to the shunt or are directly grounded. This is equivalent to allowing sound reflection equivalent to 1. This value is used in calculating the per-unit or percent excitation current. 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.

Infrared measurement devices may also be used to measure surface temperatures. To increase the time to the first voltage zero, it may be necessary to magnetically bias the core in the direction opposite to that caused by the switching impulse transient.

The post-set method does not demonstrate that the transformer would be able to withstand energizing the transformer on a short-circuit, i. The measured zero-phase-sequence impedance is represented by Z 2 N 0. Bushings shall, unless otherwise authorized by the purchaser, be those to be supplied with the transformer.

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During testing, each winding shall be subjected to its maximum calculated fault current on at least one test. This sound component is primarily produced by vibrations of the windings and tank walls when the transformer is loaded.

The measured zero-sequence impedance is represented by Z1 N s. Additional delay between tests may be required in order to let the winding cool. Sound measurements shall begin after the transformer being tested is energized and steady-state sound level conditions are established.

The reported total winding d57.12.90 is the sum of the three-phase readings if the delta is open. The impedance voltage is measured during the load loss test by measuring the voltage required to circulate rated current in the windings. Ieeee 2—When the primary winding is connected to the supply, idee one or both of the secondary windings, or either one or both of the common or tertiary windings for auto-transformers, may be short circuited for the test.

By publication of this standard, no position is taken by the IEEE with respect to the existence or c57.1.90 of any patent rights in connection therewith. Figure 30 —Example of loading back method: In all cases, the specified test condition s shall be clearly indicated in the test report. While IEEE administers the process and establishes rules to promote fairness in the consensus development process, IEEE does not independently evaluate, test, or verify the accuracy of any of the information or the soundness of any judgments contained in its standards.

NOTE 1— Comparative to large power transformers, the time constant of small distribution transformers may be short due to transformer thermal characteristics and measuring equipment, which may affect the appropriateness of an exponential decay curve.

The tap connection that produces the most severe stress is determined by calculation and should be agreed upon between the manufacturer and the purchaser.

The routine impulse test for distribution transformers applies to overhead, pad-mounted, and underground liquid-immersed distribution transformers with requirements specified in IEEE Std C Technical revisions were prepared by various groups within the IEEE Transformers Committee and have been surveyed and approved by these groups up through the subcommittee level.

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For one- third octave or narrowband measurements, the 5 dB difference shall apply to the main frequency components of the transformer noise; refer to NOTES 1, 2, and 3 in When the difference between the ambient sound pressure level and the combined transformer and ambient sound pressure level is less than 5 dB, and it is desired only to know the sound pressure level isee the transformer does not exceed, a correction of st.

External shielding may be used to avoid air corona, such as may occur at the bushing terminals or grounded projections. When transformer sound emissions are measured in an enclosed space, sound reflections from walls or other large objects iere influence the results because the sound contains discrete tones that are affected by room atd, room geometry, or reflecting objects.

For single-phase transformers, the three-phase bank power rating and associated phase-to-phase voltage should be used in the above equation. As an exception to the previous rule for selecting the two extremes and middle tap changer positions, for transformers using a reactor-type load tap changer, stc of the tests shall be performed in a bridging position.

IEEE Standard C | legal definition of IEEE Standard C by

NOTE 3—The above calculations would not be needed when purchasers require adhering to specified no-load noise level guarantees, e. If the iee capacities of the different windings are not alike, the current held for the impedance test should correspond to the capacity of the lower c57.112.90 winding of the pair of windings under test.

Short out one phase of the winding to create a virtual neutral for testing purposes. That period of time should be allowed to elapse before taking the first reading when final winding hot-resistance measurements are being made. Users are cautioned to check to determine that they have the latest edition of any IEEE standard.