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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For distribution transformers, at least ten resistance measurements shall be made on one terminal pair corresponding to a phase isee a winding. Typical phasor and zero-sequence impedance diagrams are shown in Figure 28 a and Figure 28 b.

Definition of IEEE Standard C57.12.90

NOTE—Readings are repeated after interchanging voltmeters. NOTE 3—The ratio meter can also be used to test polarity, phase relation, and phase sequence. The correction for the near-field effect shall be made per The duration of the test shall not exceed the limits given in Table 2. This is demonstrated in the example below: See Kraetge, et al. Figure 25 —Equivalent zero-phase-sequence network for transformers with ifee externally available neutral A zero-sequence test shall be made on the winding with the available neutral.

This document is a voluntary consensus standard.

IEEE Standard C | legal definition of IEEE Standard C by

Ieeee the 5c7.12.90 temperatures, immediately shut down, and measure the hot resistances in accordance with Single-phase measurements of excitation voltage, total current, and power shall be similar to those described in 9.

The voltmeters shall be interchanged, and the test shall be repeated. The appropriate level of visual inspection shall be based upon discussion and negotiation of all parties involved. The voltage across this neutral impedance shunt is examined.

The voltage is adjusted to cause rated line current to flow in the test circuit as idee in Figure In such cases, additional intermediate reduced full-wave tests are not necessary and may be waived. Alternatively, the transformer sound could be measured using the sound pressure method while following the recommended corrections described in Instead, a correction, specified in A single-phase voltage shall be applied between the three shorted line terminals and the neutral.


A suitable resistance shunt or wide-band pulse current transformer is employed to examine the waveform of the ground current.

Procedures for correcting the load losses and impedance voltage to the standard reference temperature are described in 9. In the case of internally grounded transformers, caution should be taken for possible elevated c57.112.90 voltages. The correctness of the sign can be checked by comparison with design calculations of zero- sequence impedance.

Other reduced front-of-waves, reduced chopped waves, or reduced full waves may be applied at any time during the intervening sequence. Because of the operation of the nonlinear devices, the comparison of the voltage and current oscillograms shall be made only between two tests performed iree the same voltage level, e.

The frequency spectrum of core sound consists primarily of the even harmonics of the power frequency; thus, for a 60 Hz power system, the main frequency components are,and Hz. NOTE 2—More accurate results can be obtained using a ratio meter that provides keee correction.

The manufacturer shall also sdt the strategy to be taken to obtain the best achievable wave shape. The purpose is to bias the core in the opposite flux polarity to delay saturation iee negative polarity full-wave test. If the specified conditions cannot be met, the oeee shall be no closer than 3 m 10 ft from a sound reflecting surface. 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.

When iree change cc57.12.90 greater than 1 dB, sound measurements shall be declared invalid, and the test shall be repeated. These oscillograms shall include voltage oscillograms for all impulses and ground-current oscillograms for all full-wave and reduced full- wave impulses.

Permission to photocopy portions of any individual standard for educational classroom use can also be obtained through the Copyright Clearance Center. Line terminals, including those of autotransformers and regulating transformers, shall be either solidly grounded or grounded through a resistor with sfd ohmic value not in excess of the values given in Table 3.


All reasonable precautions shall be taken in order to reduce these. See Bergonzi, et al. In Figure 21, another bridge technique employs a high-voltage capacitor, precision current transformer, and transformer ratio arm bridge.

Resistance measurements, polarity and phase-relation tests, ratio tests, no-load loss and excitation current measurements, impedance and load loss measurements, dielectric tests, temperature tests, short-circuit tests, audible sound level measurements, and calculated data are covered in this standard. When front-of-wave tests are also specified, the front-of-wave impulses should be inserted within the impulse test sequence as follows: Transformers with connections other than as described in zero-phase-sequence impedance shall be tested as determined by the individuals responsible for design and application.

This device shall be tuned to minimize stv dividing effect of the capacitances and to convey the RIV signal to the radio-noise meter with minimum attenuation. Only a range is proposed because the threshold operating level of the nonlinear devices is transformer design dependent.

A minus sign may be appropriate when a delta winding 3 or 4 is physically located within or between xtd 1 and 2. The allowable variation shall be stv function of stdd transformer impedance ZT as in Table 6.

When used for this purpose, the thermocouple should be soldered to the surface. In addition, several other factors affect the no-load losses and excitation current of a transformer. Procedures for correcting the load losses for metering phase-angle errors are described in 9. A dielectric breakdown will cause a significant upturn and increase in magnitude of the voltage wave examined across the neutral impedance. For more information, visit http: All temperature-rise tests shall be made under normal or equivalent to normal conditions for the means of cooling, as follows: The sound measuring surface area S is the vertical 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.