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Three operating modes of the transformer

Transformer is an important electrical equipment in the power network. Due to the long time running continuously, two or more transformers are normally operated in parallel during operation in order to make the transformers operate safely and economically and to improve the reliability and flexibility of power supply. Transformer parallel operation, that is, two or more transformers in parallel with the primary winding of the same voltage on the bus, the secondary winding in parallel to run on another voltage bus. Its role is: When a transformer fails, the parallel operation of other transformers can still continue to run, to ensure that important users of electricity; or when the transformer needs overhauling can be paralleled standby transformer, then the transformer to be overhauled power failure Maintenance, both to ensure the planned maintenance transformer, but also ensure uninterrupted power supply, improve the reliability of power supply. In addition, due to the strong seasonality of electricity load, some transformers can be put out of operation in light load season, which can reduce the no-load loss of the transformer, improve the efficiency, reduce the reactive excitation current, improve the power factor of the power grid, System economy.
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1, normal operation mode - rated parameters and the following operation, long-term operation;
2, the normal overload operation mode - the load exceeds the allowable value of the operation, in the insulation and life is not affected under the premise of allowing a certain period of time (according to the overloading of the upper oil temperature before setting);
3, accident overload operation - When the power system accident, in order to ensure the reliability of power supply, transformers to allow short-term overload capacity
Transformer parallel operation of the best running situation is: When the transformer has been juxtaposed, but not yet with the load, there should be no circulating current between the various transformers; at the same time bring the load after each transformer can be a reasonable distribution of load, that should be in accordance with the Their respective capacity proportion to share the load. Therefore, in order to achieve the ideal operating conditions, the transformer must be parallel operation to meet the following conditions:
(1) Each transformer voltage ratio (ratio) should be the same
(2) The impedance voltage of each transformer should be equal
(3) The wiring group of each transformer should be the same.