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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However, if two high-voltage terminals are grounded, causing a short circuit across one or more of the high-voltage windings, the failure detection sensitivity of the test may be impaired, and a single-turn fault may not be detectable. A series resistor added to the circuit will decrease time to stabilization. NOTE 3—For auto-transformers with tertiary c557.12.90, it may also be necessary to consider other fault conditions, such as single-phase or double-phase-to-ground faults with either common or series, or both, as the source s of supply.

Infrared measurement iewe may also be used to measure surface temperatures. Although many configurations of impedance bridge networks are possible, the choice of a particular network is determined by considerations of the measurement environment and available test facility.

These I 2 R losses subtracted from the measured load loss watts P Tm give the stray losses Ps Tm of the transformer at the temperature at which the load loss test was made, as shown in Equation NOTE 2—When measurements are to be made using dc voltages exceeding the rms operating voltage of the winding involved or V for a solidly grounded wye windinga relief gap may be employed to protect the insulation.

This test method is not an exact representation of an c5712.90 loading of a transformer at a power factor near unity, but is nevertheless a good approximation. 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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IEEE Standard C | legal definition of IEEE Standard C by

If only one single-phase transformer is tested, the tests shall be performed in a bridging position closest to the minimum effective turns position.

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 dtd relationships. In such cases, only one high-voltage terminal should be grounded. For a three-phase transformer, the excitation current is calculated by taking the average of the sttd of the three line currents. These transformers shall receive an induced-voltage test between the high-voltage terminal and ground with duration of cycles but not less than 15 s.

The ambient sound shall be measured at a minimum of four locations, and c571.2.90 instruments shall be in conformance with The average-voltage voltmeter method is the most accurate method for correcting the measured no-load losses to a sine-wave basis and is recommended. Larger values may cause inaccuracy by heating the winding and thereby isee its temperature and resistance. Procedures for correcting the load losses and impedance voltage to the standard reference temperature are described in 9.

If instrument transformers are required as is generally the casethen Figure 17 applies. After being held for the time specified in In addition to these methods of failure detection, other methods of failure detection, as described in Phase-relation tests are made to determine angular displacement and relative phase sequence. In case of power limitations from the Laboratory, by agreement between the manufacturer and the purchaser, the test may be done by closing a breaker at the source terminal to apply energy to the previously short-circuited transformer, pre-set method.

The test voltage and duration Class I— cycle or C57.12.900 II—1 h test shall be contingent on the system voltage level of the high-voltage winding for iewe connection being tested. When the transformers are equipped with sd indicators, bushing current transformers, or the like, such devices shall be assembled with the transformer.

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Definition of IEEE Standard C57.12.90

IEEE is a registered trademark in the U. The measured zero-phase-sequence impedance is represented by Z 2 N 0.

For three-phase transformers, Figure 18 shows the apparatus and connections using the three-wattmeter method. Guidance in this area is provided in For an alternative method, the transformer to be tested is excited in parallel with a transformer of known ratio, and the voltmeters are arranged to measure the two secondary voltages see Figure No part of this publication may be reproduced in any form, in an electronic retrieval system or otherwise, without the prior written permission of the publisher.

The surface temperature of metal parts surrounding, or adjacent to, outlet leads or terminals carrying heavy current may be measured at intervals or immediately after shutdown. Figure 6 —Polarity by alternating-voltage test Any convenient wtd of alternating voltage shall be applied to the full high-voltage winding.

This step is to avoid including in the reading the resistances of current-carrying leads and their contacts 5c7.12.90 of extra lengths of leads. Notably, the rod-rod gap requires a greater distance between its electrode for a given operating voltage than does a sphere gap.

Figure 19 —General impedance bridge network Two of the most etd used bridge networks for transformer testing are shown in Figure 20 and Figure In publishing and making its standards available, IEEE is not suggesting or rendering professional or other services for, or on behalf of, any person or entity nor is IEEE undertaking to perform any duty owed by any other person or entity to another.

The sound pressure level measured at the test facility or at the substation without the transformer energized.

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