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 measured zero-phase-sequence impedance is represented by Z 2 N 0. The frequency spectrum of this sound component typically consists of broadband fan noise, plus discrete tones of low levels at the fan blade passage frequency and its harmonics.

IEEE Standard C | legal definition of IEEE Standard C by

An applied- potential test shall be applied to all windings that are not permanently grounded. Line terminals, including those of autotransformers and regulating transformers, shall be either solidly grounded or grounded through a resistor with an ohmic value not in excess of the values given in Table 3. The number of full wave impulses applied during the test sequence has increased from one to two or three. The voltage shall be measured with a voltmeter responsive to the average value of the voltage but scaled to read the rms value of a sinusoidal wave having the same average value.

The input or output terminals are shorted, and voltage at rated frequency is applied to the other terminals. This device shall be tuned to minimize the dividing effect of the capacitances and to convey the RIV signal to the radio-noise meter with minimum attenuation. While IEEE administers the process and establishes rules to promote fairness in the consensus development process, IEEE does not independently evaluate, test, or verify the accuracy of any of the information or the soundness of any judgments contained in its standards.

The ratio of the useful power output of a transformer to the total power input.

Definition of IEEE Standard C57.12.90

When transformer sound emissions are measured in an enclosed space, sound reflections from walls or other large objects can influence the results because the sound contains discrete tones that are affected by room acoustics, room geometry, or reflecting objects.

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Rms current is recorded simultaneously during the test for no-load losses using the average- voltage voltmeter method. However, during the standardized switching impulse tests, because of the potentially high energy level contained in switching surges, provisions shall be made so that these devices will not operate within any of the winding sections. A neutral impedance shunt, using suitable values of resistance and capacitance, is employed to record waveforms for comparison.

Results shall be multiplied by to obtain the percentage of regulation. 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.

The resultant waveshape time parameters for these two phases shall be considered valid and no waveshape time adjustments are required. When performing winding resistance measurements on a transformer that utilizes series transformers for load tap changing, care is required to increase the likelihood that the whole circuit, consisting of the main and series transformer windings, is saturated before stable readings of the combined winding resistances can be obtained.

In order of preference, the tests may be conducted by either of the following methods: For nominal system voltages of 15 kV and below, only the series connections shall be tested, unless tests on both connections are specified. For this reason, IEEE and the members of its societies and Standards Coordinating Committees are not able to provide an instant response to comments or questions except in those cases where the matter has previously been addressed.

Details of separate testing of bushings for use on transformers connected to gas-insulated equipment shall be agreed upon by the manufacturer and purchaser prior to the design of the transformer. NOTE 1—For core noise, the range of the main frequency components depends on core size, material, and operating flux density. NOTE 2—In interpreting the results of power-factor test values, the comparative values of tests taken at periodic intervals are useful in identifying potential problems rather than an absolute value of power factor.

Any appropriate measuring devices may be used, as long that they give correct measurements with appropriate sensitivity, precision, and uncertainty. An equivalent three-winding impedance network, as shown in Figure 23, can be derived from Equation 4Equation 5and Equation iee Definitions For the purposes of this document, the following sdt and definitions apply.

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NOTE 1—The 4-wire measuring method is generally required to attain these reproducible readings. The partial discharge meter shall be coupled to the line terminal s of the winding s under test through the voltage tap of the bushing s or through a suitable coupling capacitor connected in parallel with the bushing.

A minus sign may be appropriate when a delta winding 3 or 4 is physically located within iee between windings 1 and 2. For the common winding resistance, the current shall be circulated between the high-voltage and neutral terminals, and the voltage shall be measured between the low-voltage and neutral terminals. NOTE 4—It is recommended that the tolerance on the agreed test current values and the duration of the tests are in line with those prescribed for two-winding transformers and that the test sequence is selected according to the expected increase of electrodynamics forces.

The short circuit shall be applied by means of suitable low-resistance connectors. 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 iee services related to the scope of the IEEE standard.

Load losses and impedance voltage During testing, each winding shall be subjected to its maximum calculated fault current on at least one test.

This method provides the closest simulation to actual loading as both no-load and load losses are present in the transformer. NOTE 1—The voltage level to be applied for the intermediate reduced full wave is not specifically given. They shall be located about mid-height of the transformer and 1 m to 2 m 3 ft to 6 ft from the transformer. A room with a c57.12.9 floor and an undetermined amount of sound-absorbing materials on the walls and ceiling.

The reported final test data shall include the measured sound levels along with the corrections used in determining the final value s.

These measurements shall be made in c57.12.900 with That period of time should be allowed to elapse before taking the first reading when final winding hot-resistance measurements are being made.

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