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 waveforms in both tests are compared with pre-established levels. 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. 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 sgd radiators. Where agreed to by both the purchaser and the manufacturer, radio c5.712.90 voltage RIV measurements may be used in lieu of, or in conjunction with, apparent charge measurements.

IEEE Standard C | legal definition of IEEE Standard C by

Current flowing in the limiting resistor shall not interfere with the ability to detect a staged single-turn fault. During this 1 h period, partial discharge measurements shall be made at 5 min intervals.

Electronic switching power supplies may be used as voltage sources; however, batteries or filtered rectifiers may also be used, especially in instances where less ripple is desired in the measurement. This test method is not an exact representation of an actual loading of a transformer at a power factor near unity, but is nevertheless a good approximation.

The two extreme tap positions and the middle tap position shall be used, one tap position for testing each of the three individual phases of a three-phase transformer or three single-phase transformers of a three-phase bank.

This goal can be accomplished by passing a small direct current through the winding between impulses by reversing the switching impulse polarity on successive applications or by applying reduced impulses of opposite polarity before each full switching impulse transient. Infrared measurement devices may also be used to measure surface temperatures.


When appropriate corrections are applied to the voltmeter readings, tests may be made at only one voltage. Such noise should be investigated. Using this sequence, the beginning tests involve voltages and currents, which are usually reduced as compared with rated values, thus tending to minimize problematic effects to the transformer.

Therefore, environmental corrections explained in The same test equipment shall be used for both cold-resistance and hot-resistance measurements. When the transformer is connected in the two-winding connection for the test, the current held shall be the rated current of the excited winding, which may or may not be the same as rated line current.

Automatic recording of the resistance data is recommended so that the time to saturation and the variability of the resistance readings after stabilization can be documented.

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. The two voltmeters shall be read simultaneously. Equation 2 is valid only for test voltages with moderate waveform distortion.

When front-of-wave tests c57.12.0 also specified, the front-of-wave impulses should be inserted within the impulse test sequence as follows: 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 treatment of the individual load losses and impedance voltages for temperature corrections, and so on, is the same as for two-winding single-phase transformers. Examples of procedures include the following: Circulate load current by opening the connections of either pair of windings at one point and impress a voltage across the break just sufficient to circulate rated current at rated frequency for the connection and loading used.

Observed differences in the waveforms may be indications of failure, or they may be due to non-injurious causes. The methods described in this standard are applicable to distribution and power transformers of present-day design that are immersed in an insulating liquid. The sound iee surface area S is the stv area in square meters enveloping the transformer measurement surface on which the sound measurement points are located plus the horizontal plane bounded by the vertical measurement surface.


It has some similarities to classic Schering and Maxwell leee. When the current held in any of the windings under test differs from the iewe current, the observed differences between the average winding temperature at shutdown and the average liquid temperature at shutdown shall be corrected to give the average temperature rise of the windings at the rated current by using Equation It is generally expressed in percent of the rated current of the winding in which it is measured.

Definition of IEEE Standard C57.12.90

Under those conditions, the correction, described in The percent resistance is the measured losses expressed as a percentage of the rated kilovoltampere of the teaser winding. Notably, the rod-rod gap requires a greater distance between its electrode for a given operating voltage than does a sphere gap.

All loads being at nearly zero power factor.

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 d57.12.90 taken within 4 mins after shutdown.

For power transformers, the last hot resistance measurement shall be taken no sooner than 10 min from shutdown.