(3)确定合理的主接线方案、运行方式及限流措施。 (4)保护电力系统的

(3) Determine a reasonable main wiring scheme, operation mode and current limiting measures. <br>(4) Protect the electrical equipment of the power system from damage in the most serious short-circuit state, and minimize the harm caused by short-circuit faults. <br>4.1.2 General provisions for short-circuit current calculation <br>(1) It should be calculated according to the design planning capacity of the project, and the long-term development plan of the power system should be considered, generally 5-10 years after the completion of the current project. <br>(2) When determining the calculation of short-circuit current, the normal wiring method that may cause the maximum short-circuit current should be used, not just the wiring method that may be operated in parallel during the switching process. <br>(3) Among the various short-circuit types, the most serious type of short-circuit type should be selected, generally calculated according to the three-phase short-circuit. <br>(4) The place where the short-circuit current through the device is the largest in the normal wiring mode is called the short-circuit calculation point. <br>(5) In engineering design, short-circuit current calculation generally adopts practical calculation, that is, calculates each component of short-circuit current under certain assumptions. <br>4.1.3 Basic assumptions for short-circuit current calculation <br>(1) During normal operation, the three-phase system operates symmetrically: <br>(2) The phase angle of the electromotive force of all power supplies is the same: <br>(3) The magnetic circuit of each component in the power system is not saturated, that is, with a core The reactance value of the electrical equipment does not change with the current size: <br>(4) The arc resistance of the short circuit point and the excitation current of the transformer are not considered: <br>(5) The resistance of the component is omitted, the capacitance of the transmission line is omitted, and the effect of the load is ignored: <br>(6) When the system is short-circuited, it is a metallic short circuit.

(3) To determine a reasonable main wiring scheme, mode of operation and current restriction measures. <br>(4) Protect the electrical equipment of the power system from damage in the most severe short-circuit state, and minimize the damage caused by short circuit failure. <br> 4.1.2 General regulations for short-circuit current calculation<br> (1) Should be calculated according to the design and planning capacity of the project, and consider the vision development plan of the power system, one - for the completion of the project 5 to 10 years.<br>(2) When determining the short-circuit current calculation, the normal wiring mode of the maximum short-circuit current may occur should be, and not only in the same way that may be run side by side during the switching process.<br>(3) In the case of the most serious short-circuit type should be selected in various short-circuit types, it is generally calculated according to the three-phase short circuit.<br>(4) The short-circuit current through the device is the largest location in normal wiring mode, called the short-circuit calculation point.<br>(5) In engineering design, short-circuit current calculation - like the use of practical calculation, that is, under certain false conditions to calculate the short-circuit current components.<br> 4.1.3 Basic assumptions for short-circuit current calculation<br>(1) When working normally, the three-phase system operates symmetrically:<br>(2) The electric potential phase angle of all power supplies is the same:<br>(3) The magnetic circuit of each component in the power system is not saturated, i.e. the electrical resistance value of the electrical equipment with iron core does not change with the current size:<br>(4) The arc impedance of the short circuit point and the excitation current of the transformer are not considered:<br>(5) the resistance of the component is omitted, the capacitance of the transmission line is omitted, and the effect of the load is not counted:<br>(6) The system is shorted to metal.

(3) Determine the reasonable main wiring scheme, operation mode and current limiting measures.<br>(4) Protect the electrical equipment of the power system from damage in the most serious short-circuit state, and minimize the harm caused by short-circuit fault.<br>4.1.2 general provisions for short circuit current calculation<br>(1) It shall be calculated according to the design planning capacity of the project, and the long-term development plan of the power system shall be considered. Generally, it is 5-10 years after the completion of the project.<br>(2) When determining the short-circuit current calculation, the normal wiring mode that may produce the maximum short-circuit current shall be followed instead of the wiring mode that may operate in parallel during the switching process.<br>(3) In all kinds of short-circuit types, the most serious short-circuit type should be selected, generally calculated as three-phase short-circuit.<br>(4) In the normal wiring mode, the maximum short-circuit current passing through the equipment is called the short-circuit calculation point.<br>(5) In engineering design, short-circuit current calculation generally uses practical calculation, that is, under certain assumptions to calculate the various components of short-circuit current.<br>4.1.3 basic assumptions of short circuit current calculation<br>(1) In normal operation, the three-phase system operates symmetrically:<br>(2) All power supplies have the same EMF phase angle:<br>(3) The magnetic circuit of each component in the power system is not saturated, that is, the reactance value of electrical equipment with iron core does not change with the current size:<br>(4) The arc impedance at the short circuit point and the excitation current of the transformer are not considered:<br>(5) The resistance of components is omitted, the capacitance of transmission lines is omitted, and the influence of load is ignored:<br>(6) The short circuit of the system is metallic.<br>