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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Single-phase measurements of excitation voltage, total current, and power shall be similar to those described in 9.
Definition of IEEE Standard C57.12.90
The voltmeters shall be interchanged, and the test shall be repeated. The time interval from the start of the transient to the time when the maximum amplitude is reached. This method employs two parallel-connected voltmeters: However, it is recommended that a test connection be made to the junction of the two winding sections and that tests be made during manufacture to prove the desired phase relationships.
The load loss watts and applied voltamperes will be the same, regardless of whether series c5.12.90 common windings are treated as separate windings in the two-winding connection or are connected in the autotransformer connection, so long as rated winding current is held in the first case and rated line current in the second case.
The required total losses for the total loss run shall be the sum of thermal connection load loss plus no-load loss measured in accordance with Clause 8. The magnitude of load sound is highly dependent on the transformer oeee. 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 under test.
Normally such systems are solidly grounded neutral systems or low impedance grounded neutral systems.
NOTE 1—For core noise, the range of the main frequency components depends on core size, material, and operating flux density. NOTE 3— The Working Group is initiating an investigation to define appropriate curves concerning NOTE 1 and NOTE 2 for a future modification to this clause f When the series of hot resistance measurements on a distribution transformer is made on only one terminal pair under test, the resistance-time data obtained on one phase of a winding shall be used to determine the correction to shutdown for the other phases of the same winding, provided the first measurement of each of the other phases has been taken within 4 mins after shutdown.
If different tap positions are proposed to be used during test, it should be agreed upon between manufacturer and purchaser prior to design of the transformer. Ambient sound pressure levels shall be measured using the same bandwidth A-weighted, one-third octave, or discrete frequencies specified for measuring the transformer sound.
The readings of both voltmeters are employed to correct the no-load losses to a sine-wave basis, using Equation 2 in accordance with 8. Thus, the resulting difference between the applied impulse and the voltage across the resistor e.
IEEE Standard C | legal definition of IEEE Standard C by
In any case, the full winding not merely a portion of the winding should be used whenever possible. Ifee 2—When using the pre-set method for a transformer with single concentric windings, the supply should preferably be connected to the c557.12.90 farther from the core, the winding closer to the core being short-circuited.
Chopped-wave tests cannot be compared during and after chopping. Users are cautioned to check to determine that they have the latest edition of any IEEE standard.
It may then be necessary to increase the source voltage to compensate for the voltage drop in the series resistor. If, during switching impulse tests, a flashover is observed across line bushings, the nonlinear devices may limit the resulting overvoltages produced within the winding sections after flashover. When using three-phase power, and inequality of the phase voltage is found, the connection should be changed.
Any such indication shall be carefully investigated by observation, by repeating the test, and by other diagnostic tests to determine whether a failure has occurred. The c5.712.90 test sequence shall be performed: Apply a single-phase voltage to winding 1 between the shorted line terminals of Winding 1 and its neutral. NOTE 1—The 4-wire measuring method is generally required to attain these reproducible readings.
The value to be used for this correction is —1. Figure 15 is a schematic representation of the equipment and connections necessary for conducting no-load loss measurements of a three-phase transformer when instrument transformers are necessary. They shall be protected from drafts and radiant heat from the transformer under test or other sources. The same test equipment shall be used for both cold-resistance and hot-resistance measurements. The voltage zero following the instant of chopping shall occur within some layer windingsthe circuit response after chopping may not be oscillatory; it may be overdamped.
Only instrument transformers meeting 0. The hot resistance-time data collected shall be fitted to an exponential decay curve using the method of least squares. By making these documents available for use and adoption by public authorities and private users, IEEE does not waive any rights in copyright to the documents.
The extent of the visual inspection shall be established on the basis of combined evidence obtained from the measurements described in A neutral impedance shunt, using suitable values of resistance and capacitance, is employed to record waveforms for stdd.
Patents Attention is called to the possibility that implementation of this standard may require use of subject matter covered by patent rights.
It is intended for use as a basis for performance and proper testing of such transformers. Ambient sound pressure level corrections may be made at each microphone location before the average transformer sound pressure level is computed. If such a performance is required per the client requirements, the transformer should be tested using the pre-set method with the pre-set short circuit applied on one of the axial split windings.
In making the chopped-wave test, failure of the chopping gap or any external part to sparkover, although the voltage oscillogram shows a chopped wave, is a definite indication atd a failure either within the transformer or in the test circuit. An impulse voltage with 1. The ultimate liquid temperature rise above ambient shall be considered to be reached when the top liquid temperature rise does not vary more than 2. This is demonstrated in the example below: Apply a single-phase voltage to winding 2 between the shorted line terminals of winding 2 and its neutral.
Any differences in the wave shape between the reduced full wave and the final full wave detected by comparison of the two current oscillograms may be indications of failure or deviations due to noninjurious c57.12.09.
Under these conditions, no correction, to the measurements using the sound-intensity method, is needed. Extremes of the tap range all taps out or all taps in normally produce the most severe stresses, and they are recommended. In all cases, the specified test condition s shall be clearly indicated iewe the test report. For delta-connected windings, the time can also be reduced by opening the delta connection.