Research Of Single Residual Current Protection Devices

Residual current protective device as an effective measure of safety of power supply, therefore, government have compellent require for electro-equipments RCD must be installed in many occasions. Residual current protection devices are used in low-voltage distribution network is a effective way to prevent personal electrocution, electrical fires and electrical equipments damaged. At present, residual current protective methods are using at home and abroad commonly. But the principles of existing equipments are passive, they have erroneous action,refusing action and protect ion of the dead zone, a lot of security risks are existing. These problems has not been solved effectively. Research a new principle of residual current protection and new residual current protective device is a very meaningful thing.In this paper, a new type of residual current protective device have been verified, in normal working, it don't effect on line and loads. When the line has earthing fault or people get an electric shock, protection device work at once, generate a impedance, restrict the current which flow through the body within the safety limit twenty milliseconds, protect the people. Before the fault is removed, protection device can still work normally, although the human electric shock, but there is no risk. Not only to ensure the safe operation of electrical equipment,but also avoid the occurrence of an electric shock hazard to the human body.This papper research the new type of low-voltage single-phase residual current protective device's characteristics, make math analysis for protection theory and circuit model, calculated the constraints conditions when protection. On the basis of the analysis and using simulation software to verify their theoretical analysis and find reasonable component's parameters. In order to solve the problem which the important device has big size, make deeply research and many experiments to the important device's materials and shapes, effort to reduce the volume. The protection device has a special link in signal detection and processing, a link in driving and a trip institution. In order to solve the problem which the important device is inadequate intelligence, the residual current protection device uses the Single Chip Microcomputer to detect and process the fault signals, set a value software, when the line has earthing fault or people get an electric shock, only show the fault signalson the liquid crystal display, as warning.When the acquisition signal exceeds setting value for a long time, the Single Chip Microcomputer drives the switch tripping, cut off power supply. After studying, design a new type of leakage protective device which is small volume and intelligentized finally.