A Type Of Electronic Trip Unit Application In Directly Current Breaker Based On ARM Chip

With speedy development of electric power technology and huge powerdistribution demand, the distribution system’s architecture and application willbe more and more complex, that means higher reliability, higher safetyrequirement during power supply, accordingly electric power equipment isrequired more reliability, safety and easy to be operated. The directly currentbreaker is the important device in electric power system, it is widely appliedin power plant, transformer substation as the control circuit and power circuit.Except for the basic function "open" or "close" breaker under rating current,the breaker also should be rapid to open the breaker in discrimination functionwhen fault current happen. The phenomena of unwanted tripping andnon-tripping do not permit of any situation. With the national economyspeedily develop, the intelligent distribution network has been applied inmore and more field, the intelligent electronic trip unit with microcontrollerhas a wide application stage in the future.In this paper, the Hall sensor was using to monitor the signal of primarydirectly current, and use a special measure way to achieve current detect inwide range, and select the core component is ARM microcontroller, which iscalculated the secondary signal from Hall sensor, to achieve overloadprotection, short protection, instantaneous protection, the protectionparameter could be setting by customer also.In the hardware design process, we adequately consider the impact fromEMC interference and the transient overvoltage during DC breaking. PSPICEsimulation tools help us to set up model and analyze circuit, it is useful toselect electronic parts in right parameter, and it guarantee the product is reliability of design.The Hall sensor solution has been validated in real current test, and testresult show that was coincident with the theoretic design. And the productpassed "Rated service short-circuit breaking capacity" test in the external lab,product meet the national standard requirements, the product performance isreliable.