电机学电机学电机学 (16).ppt

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1、Electrical MachineryVector Group Symbol of the Three-phase Transformer3.2.1 Vector Group Symbol of the Three-phase TransformerConcept of vector group symbolVector group symbol:indicating the connection type of the high-voltage winding and low-voltage winding of the transformer and the phase relation

2、 of the corresponding line electromotive forces of the high-voltage winding and low-voltage winding.(Y,y6)The connection method of the high-voltage winding is expressed with the capital letter,and the connection method of the low-voltage winding is expressed with the small letter.The letters N,n are

3、 the symbol of leading out from neutral point.3.2.2 Confirm vector group symbol of the three-phase transformer1.Clock methodSelect the EMF vector of the line on the high voltage side to act as the long hand,and fix the long hand to point at 0 oclock(12 oclock)on the clock dial;Regard EMF of the line

4、 on the low voltage side as the short hand;The hour point which the short hand is pointing at is used as the vector group symbol of the transformer;EMF Eab on the low voltage side lags EAB on the high voltage side by 3x30.3.2.2 Confirm vector group symbol of the three-phase transformer2.Confirm vect

5、or group symbolABCXYZabcxyz*3.2.2 Vector group symbol of the three-phase transformer2.Confirm vector group symbol*ABCXYZabcxyz*3.2.3 Confirm the vector group symbol of the three-phase transformerStandard vector group symbol of the three-phase transformer in China Y,yn0；Y，d11；YN，d11；YN，y0；Y，y0.Y,yn0:

6、the neutral line can be led out from the low voltage side,so the system of three phases and four wires is formed.When the system is used for a distribution transformer,it can provide electric power for dynamic load and lighting load.Y,d11:used in the circuit for which the voltage of the low-voltage side is greater than 400V.YN，d11:used in high-voltage power transmission line so as to make the neutral point of the high voltage side of the power system possibly earthed.THANKS FOR WATCHING!