Jul,12

IEEE c57.12.00-2006 pdf free download

IEEE c57.12.00-2006 pdf free download

IEEE c57.12.00-2006 pdf free download.IEEE Standard for Standard General Requirements for Liquid-Immersed Distribution, Power, and Regulating Transformers.
IEEE Std C57.19.01 ™ , IEEE Standard Performance Characteristics and Dimensions for Outdoor Apparatus Bushings. IEEE Std C57.131 ™ , IEEE Standard Requirements for Load Tap Changers. IEEE Std C62.11 ™ , IEEE Standard for Metal-Oxide Surge Arresters for Alternating Current Power Circuits (>1 kV). IEEE Std C62.22 ™ , IEEE Guide for the Application of Metal-Oxide Surge Arresters for Alternating- Current Systems. 3. Definitions Standard transformer terminology available in IEEE Std C57.12.80 6 shall apply. Other electrical terms are defined in The Authoritative Dictionary of IEEE Standards Terms and Definitions, Seventh Edition [B14]. 7 4. Service conditions 4.1 Usual service conditions 4.1.1 General Transformers conforming to this standard shall be suitable for operation at rated kVA under the following usual service conditions. 4.1.2 Temperature 4.1.2.1 Cooling air temperature limit When air-cooled, the temperature of the cooling air (ambient temperature) shall not exceed 40 o C, and the average temperature of the cooling air for any 24 h period shall not exceed 30 o C. 4.1.2.2 Liquid temperature limit The top liquid temperature of the transformer (when operating) shall not be lower than –20 o C. Liquid temperatures below –20 o C are not considered as usual service conditions. 4.1.2.3 Cooling water temperature limit When water-cooled, the temperature of the cooling water (ambient temperature) shall not exceed 30 o C, and the average temperature of the cooling water for any 24 h period shall not exceed 25 o C. Minimum water temperature shall not be lower than 1 o C, unless the cooling water includes antifreeze suitable for –20 o C operation. 4.1.3 Altitude The altitude shall not exceed 1000 m (3300 ft).
4.1.4 Supply voltage The supply-voltage wave shape shall be approximately sinusoidal. The phase voltages supplying a polyphase transformer shall be approximately equal in magnitude and time displacement. 4.1.5 Load current The load current shall be approximately sinusoidal. The harmonic factor shall not exceed 0.05 per unit. Harmonic factor is defined in IEEE Std C57.12.80. 4.1.6 Operation above rated voltage or below rated frequency 4.1.6.1 Capability Transformers shall be capable of the following: a) Operating continuously above rated voltage or below rated frequency, at maximum rated kVA for any tap, without exceeding the limits of observable temperature rise in accordance with 5.11.1.1 when all of the following conditions prevail: 1) Secondary voltage and volts per Hertz do not exceed 105% of rated values. 2) Load power factor is 80% or higher. 3) Frequency is at least 95% of rated value. b) Operating continuously above rated voltage or below rated frequency, on any tap at no load, without exceeding limits of observable temperature rise in accordance with 5.11.1, when neither the voltage nor volts per Hertz exceed 110% of rated values. For multiwinding transformers or autotransformers, 4.1.6.1 applies only to specific loading conditions used as the basis of design. These loading conditions involve simultaneous coordination of kVA input and output, load power factors, and winding voltage combinations [see item j) of 4.3.3]. Differences in loading and voltage regulation for various output windings may prevent simultaneous achievement of 105% voltage on all output terminals. In no case shall the kVA outputs specified for any loading condition require continuous loading of any input winding in excess of its rating. 4.1.6.2 Maximum continuous transformer operating voltage The maximum continuous transformer operating voltage should not exceed the levels specified in ANSI C84.1. 4.1.8.2 System tie autotransformers Transformers identified as system tie transformers or autotransformers shall be designed for step-down operation, or step-up operation, or both, as specified by the user. 4.1.9 Tank or enclosure finish Temperature limits and tests shall be based on the use of a nonmetallic pigment surface paint finish. It should be noted that metallic-flake paints, such as aluminum and zinc, have properties that increase the temperature rise of transformers, except in direct sunlight. 4.2 Loading at other-than-rated conditions IEEE Std C57.91-1995 [B28] provides guidance for loading at other-than-rated conditions including: a) Ambient temperatures higher or lower than the basis of rating. b) Short-time loading in excess of nameplate kVA with normal life expectancy. c) Loading that results in reduced life expectancy. IEEE Std C57.91-1995 [B28] is not standard. It provides the best known general information for loading of transformers under various conditions based on typical winding insulation systems. It is based upon the best engineering information available at the time of preparation. The guide discusses limitations of ancillary components other than windings that may limit the capability of transformers. When specified, ancillary components and other construction features (cables, bushings, tap changers, oil expansion space, etc.) shall be supplied in a manner that will not limit the loading to less than the capability of the windings. 4.3 Unusual service conditions Conditions other than those described in 4.1 are considered unusual service conditions and, when prevalent, should be brought to the attention of those responsible for the design and application of the apparatus. Examples of some of these conditions are listed in 4.3.3.

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