IEEE C57.12.90-2010 pdf free download.IE EE Standard Test Code for Liquid-Immersed Distribution, Power, and Regulating Transformers .
2. Normative references The following referenced documents are indispensable for the application of this document (ie., they must be understood and used, so each referenced document is cited in text and its relationship to this document is explained). For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments or corrigenda) applies. ANSI C57.12.25, American National Standard for Transformers- Pad-Mounted, Compartmental-Type, Self-Cooled, Single-Phase Distribution Transformers with Separable Insulated High-V oltage Connectors; High-Voltage, 34 500 GrdY/19 920 Volts and Below; Low-Voltage, 240/120 Volts; 167 kVA and Smaller- Requirements.’ ANSI C84.1, American National Standard for Electric Power Systems and Equipment Voltage Ratings (60 Hert2). ANSI S1.4, American National Standard for Sound Level Meters. ANSI S1.11, American National Standard for Octave Band and Fractional-Octave-Band Analog and Digital Filters. IEEE Std 4″, IEEE Standard Techniques for High-Voltage Testing.” 5 IEEE Std C57.12.00″ “， IEEE Standard General Requirements for Liquid-Immersed Distribution, Power, and Regulating Transformers. IEEE Std C57.12.00″ *-2010, IEEE Standard General Requirements for Liquid-Immersed Distribution, Power, and Regulating Transformers (specifically, Clause 7 and Clause 10; 4.1.2, 184.108.40.206,5.9,5.10, 5.11.2, 220.127.116.11,9.1, 9.4; Table 5, Table 4, Table 13, and Table 18). IEEE Std C57.12.20” ，IEEE Standard for Overhead-Type Distribution Transformers, 500 kVA and Smaller: High Voltage, 34 500 V and Below; Low Voltage, 7970/13 800Y V and Below.
4. General 4.1 Types of tests Various types of tests (routine, design, conformance, and other) are defined in IEEE Std C57.12.80. 4.2 Test requirements A general summary of test requirements is included in Table 18 of IEEE Std C57.12.00-2010 and indicates which tests are normally considered routine, design, or other, by size and class. 4.3 Test sequence See 10.1.5.1 for the sequence of dielectric tests when lightning impulse or switching impulse tests are specified. NOTE- -To minimize potential damage to the transformer during testing, the resistance, polarity, phase relation, ratio, no-load loss and excitation current, impedance, and load loss tests (and temperature-rise tests, when applicable) should precede dielectric tests. Using this sequence, the beginning tests involve voltages and currents, which are usually reduced as compared with rated values, thus tending to minimize damaging efcts to the transformer.’ 4.4 Instrumentation Although the figures in this standard show conventional meters, adequate digital readout measuring devices and digital sampling techniques with computer calculations are considered to be satisfactory alternatives.
5.1 Determination of cold temperature The cold temperature of the winding shall be determined as accurately as possible when measuring the cold resistance. The precautions in5.1.1, 5.1.2, and 5.1.3 shall be observed. 5.1.1 General Cold-resistance measurements shall be made on a transformer only when the liquid or winding temperature is stable. The temperature is considered stable if the top liquid temperature does not vary more than2°C in a 1 h period. 5.1.2 Transformer windings immersed in insulating liquid The temperature of the windings shall be assumed to be the same as the average temperature of the insulating liquid, provided The windings have been under insulating liquid with no excitation and with no current in the windings for a minimum of 3 h for a transformer without pumps and for 1 h for transformer with pumps running before the cold resistance is measured. b) The temperature of the insulating liquid has stabilized, and the difference between top and bottom temperature does not exceed 5 °C. 5.1.3 Transformer windings out of insulating liquid The temperature of the windings shall be recorded as the average of several thermometers or thermocouples inserted between the coils, with care used to see that their measuring points are as nearly as possible in actual contact with the winding conductors. It should not be assumed that the windings are at the same temperature as the surrounding air.