差动技术（Differential technique）.docVIP

差动技术（Differential technique） Differential protection principle 1 Introduction The principle of differential protection is simple, the use of electrical quantity is simple, the protection range is clear, and the operation does not need delay. It has been used for transformer protection, and its operation is directly related to the safety of transformer. How do I know the operation of differential protection? How do I know the setting and wiring of the differential protection? Only load current test. But what quantities should be measured during the test? How do you analyze and judge the measured data? Here are some discussions on these issues. Brief principle of 2 transformer differential protection Differential protection is the use of Kirchhoffs current law work, when the transformer is outside the normal work or failure, be regarded as the ideal transformer, current transformer into and out of the current (current after conversion) is equal to the differential relay action. When the transformer is out of order, the two sides (or three sides) provide the short circuit current to the fault point, and the two current of the differential protection is proportional to the current of the fault point, and the differential relay action. Importance of 3 transformer differential protection with load test The transformer differential protection principle is simple, but the realization of complex, plus a variety of differential protection in the implementation details of each are not identical, but increased its in the practical use of the complexity, the error probability increases, the correct action rate decreased. For example, xujigongsi microprocessor-based transformer differential protection calculation Y- delta connection transformer Y side two times rated current is multiplied by the company, and the protection should be multiplied by the nari. These small differences, design, installation, setting personnel is easy to negligence and confusion, resulting in protection