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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The average winding temperature rise for each terminal pair corresponding to a ieee phase shall be corrected for actual test currents, test losses, and altitude as prescribed in In addition, it may be necessary to convert the resistance measurements to the temperature at ste the impedance loss measurements were made.

External connection of other windings shall be as described in zero-phase-sequence impedance for various transformer connections. They should be fully investigated and explained by a new reduced full-wave test and full-wave test.

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.

When the latter voltage reading sttd less than the former indicating the approximate difference in voltage between the high-voltage and low-voltage windingsthe polarity is subtractive. The time to crest should be defined and determined as described in 8. The ambient sound corrections shall be made with the identical frequency bandwidths that are used to measure the combined transformer and ambient sound pressure level. Additional delay between tests may be required in order to let the winding cool.

Include the following information ueee the sound-measuring f57.12.90 For distribution transformers, at least ten resistance measurements shall be made on one terminal pair corresponding to a phase of a winding. A dielectric breakdown will cause a difference in jeee waveforms. NOTE 2—When the primary winding is connected to the supply, either 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.

Definition of IEEE Standard C57.12.90

The ability to withstand the dynamic effects of short-circuit should preferably be demonstrated by test; if not possible it may be demonstrated by leee and design considerations per IECupon agreement between manufacturer and purchaser.

Autotransformers and split-coil transformers require special precautions and it may be required to use the post-set method instead of the preferred pre-set method.

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Measurement of excitation current is usually carried out in conjunction with the tests for no- load losses. Figure 16 iewe when instrument transformers are not required.

The load audible sound level shall be measured at rated frequency and at the rated tap position unless otherwise specified by the purchaser. IEEE does not warrant or represent the accuracy or content of the material contained in its standards, and expressly disclaims all warranties express, implied and statutory not included in this or any other document relating to the standard, including, but not limited to, the warranties of: 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 3—If the above prescribed maximum lead length to the chopping gap cannot be achieved because of the presence of transformer accessories such as coolers or any other transformer accessories, then the shortest possible lead length should be used during tests.

Where field dielectric tests are required, low-frequency applied-voltage and induced-voltage tests shall be used. The ratio of the load losses in kilowatts at the temperature of test to the impedance kilovoltampere at the temperature of test is the load loss power factor of the transformer during the test and is used for correction of phase-angle error as specified in this standard. The existence of an IEEE standard does not imply that there are no other ways to produce, test, measure, purchase, market, or provide other goods and services related to the scope of the IEEE standard.

The extent of necessary visual inspection may range from an inspection through openings on the tank hand hole, manhole to complete dismantling of the core and coils. For three-phase transformers, Figure 18 shows the apparatus and connections using the three-wattmeter method. For single-phase power the circuit is configured such that there is no shift in the neutral c571.2.90 this requires shorting out one phase as shown in Figure 9.

Equation 2 is valid only for test voltages with moderate waveform distortion. Apply srd single-phase voltage to winding 2 between the shorted line terminals of winding 2 and its neutral. This sound component is primarily produced by vibrations of the windings and tank walls when the transformer is loaded. The impedance voltage is the phasor sum of the two components.

Technical revisions ste prepared by various groups within the IEEE Transformers Committee and have been surveyed and approved by these groups up through the subcommittee level. The term interconnected windings shall be interpreted to mean windings in which one or more electrical phases are linked by more than c7.12.90 magnetic phase.

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This will help to avoid saturation of the core, which could lead to an excessive magnetizing current superimposed on the short-circuit current during the first few cycles. A low-impedance shunt, consisting of a parallel combination of resistance and capacitance RCis employed.

For the correct assessment of the grounding conditions not only the physical grounding conditions around the relevant location but the total system should be considered. Only a range is proposed because the threshold operating level of the nonlinear devices is transformer design dependent.

The number of full wave impulses applied during the test sequence has increased from one to two or three. Notably, the rod-rod gap requires a greater distance between its electrode for a given operating voltage than does a sphere gap.

Unusual noise within the transformer at the instant of applying the impulse is an indication of trouble. Three-phase transformers shall be excited from three-phase sources.

The duration of the test shall not exceed the limits given in Table 2. For transformers having an overall tank or enclosure height of 2. Included are methods of correcting the measurements for environmental factors, namely c57.2.90 noise and wall sound reflections. No required test is proposed to determine the phase relationships between the line-end and neutral-end sections of a zigzag winding. The resultant waveshape time parameters for these two phases shall be considered valid and no waveshape time adjustments are required.

The voltmeters shall be interchanged, and the test shall be repeated. A series resistor added to the circuit will decrease time to stabilization.

IEEE Standard C | legal definition of IEEE Standard C by

Where the cooling class of the transformer involves more than one kilovoltampere rating, the lowest kilovoltampere rating is used to determine the base current. Axial-split transformers shall preferably c571.2.90 tested by closing a breaker at the faulted terminal to apply short-circuit iese the previously energized transformer, post-set method.

In all cases, the specified test condition s shall be clearly indicated in the test report. If the kilovoltampere capacities of the different windings are not alike, the current held for the impedance test should correspond to the capacity of the lower rated winding of the pair of windings under test.

Stray losses may also be caused by circulating currents in parallel windings or strands.