1、附录 INTERNATIONAL STANDARD POWER TRANSFORMERS 1. Scope and service conditions 1.1 Scope This part of international Standard IEC60076 applies to three-phase and single-phase power transformers (including auto-transformers) with the exception certain categories of small and special transformers such as
2、: -single-phase transformers with rated power less than 1 KVA and three-phase transformers less than 5 KVA； - instrument transformers； - transformers for static convertors； -traction transformers mounted on rolling stock； -starting transformers ； -testing transformers ； -welding transformers ； When
3、standards do not exist for such categories of transformers, this part may still be applicable either as a whole or in part. 1.2 Service conditions This part gives detailed requirement for transformers for use under the following conditions: a) Altitude A height above sea-level not exceeding 1000 m .
4、 b) Temperature of ambient air not below - 25 and not above +40 .For water-cooled transformers , a temperature of cooling water at the inlet not exceeding +25 . c) Wave shape of supply voltage A supply voltage of which the wave shape is approximately sinusoidal. NOTE This requirement is normally not
5、 critical in public supply systems but may have to be considered in installations with considerable convertor loading in such cases there is a conventional rule that the deformation shall neither exceed 5 % total harmonic content nor 1 % even harmonic content .Also note the importance of current har
6、monic for load loss and temperature rise. d) Symmetry of three-phase supply voltage For three-phase transformers, a set of three-phase supply voltage which are approximately symmetrical . e) Installation environment An environment with a pollution rate that does not require special consideration reg
7、arding the external insulation of transformer bushings or of the transformer itself. An environment not exposed to seismic disturbance which would otherwise require special consideration in the design. This is assumed to be the case when the ground acceleration level is below 2 m/s . Provision for u
8、nusual service conditions Any unusual service conditions which may lead to special consideration in the design of a transformer shall be stated in the enquiry and the order . These may be factors such as high altitude , extreme high or low temperature ,tropical humidity , seismic activity , severe c
9、ontamination , unusual voltage or load current wave shapes and intermittent loading . They may also concern conditions for shipment ,storage and installation , such as weight or space limitations. Supplementary rules for rating and testing are given in other publications for : a. Temperature rise an
10、d cooling in high ambient temperature or at high altitude for oil-immersed transformers , and for dry-transformers . b. External insulation at high altitude :for oil-immersed transformers, and for dry-transformers. 2. Definitions For the purpose of this part , the following definitions shall apply.
11、2.1 General Power transformer A static piece of apparatus with two or more winding , by electromagnetic induction , transformers a system of alternating voltage and current into another system of voltage and current usually of different values and at the same frequency for the purpose of transmittin
12、g electrical power . auto-transformer a transformer of which at least two windings have a common part. booster transformer a transformer of which one winding is intended to be connected in series with a circuit in order to alter its voltage and/or shift its phase . The other winding is an energizing
13、 winding. Oil-immersed type transformer a transformer of which the magnetic circuit and winding are immersed in oil. NOTE For the purpose of this part any insulating liquid , mineral oil or other product , is regard as oil . dry-type transformer a transformer of which the magnetic circuit and windin
14、g are not immersed in an insulating liquid . oil preservation system the system in an oil-immersed transformer by which the thermal expansion of the oil is accommodated . Contact between the oil and external air may sometimes be diminished or prevented . 2 2Terminals and neutral point terminal a con
15、ducting element intended for connecting a winding to external conductors line terminal a terminal intended for connecting to a line conductor of a network neutral terminal a) For three-phase transformers and three-phase banks of single-phase transformers: The terminal or terminals connected to the c
16、ommon point (the neutral point ) of a star-connected or zigzag connected winding . b) For single-phase transformers: The terminal intended for connection to a neutral point of a network . corresponding terminal terminal of different windings of a transformer , marked the same letter or corresponding symbol. 2.3Windings winding
