On-line Monitoring Of HVCB

On-line monitoring of HVCB is the precondition of predicting maintenance, is the key element of reliable run, and is the important supplement to the traditional off-line preventive maintenance. In fact , the faults are made by HVCB, no matter in accidental numbers or in power failure times, is over 60% of total faults . So it has determinative importance for improving the reliability of power supply. And this can greatly decrease the capital waste used by dating overhaul. On the other hand , the technique of HVCB On-line monitoring will create conditions for the conversion that plan-overhaul change into state-overhaul, and establish foundation for the exploitation and application of the GIS and intelligentized HVCB.In this paper, the inspecting way of HVCB mechanism characteristic is discussed. For improving the real time performance, the capturing function timers are used in the journey orientation for speed and journey monitoring. Consideing the burning coil phenomena of HVCB, The concept of sub-circuit protector is presented, the protecting principle of sub-circuit protector is given, and the way that we carry it into practice is discussed in this paper as well. Analyzing the actuality of integrality monitoring of breakers coils at home and abroad, a really complete monitoring scheme is given. Furthermore, the scheme is given. Furthermore the scheme that we offered has been combined with sub-circuit integrality monitoring theory, in order to ensure that it has the two functions as a whole. According the shut-off times at rated short circuit given by HVCB manufacturer and combining the formula of touch electricity wear and tear, the electricity longevity loss can be calculated in each operation, and the remained longevity can be forecast too. ALL efforts ensure that the theory is in accord with engineering practicality.The operating current of HVCB is calculated by using most slope algorithm. For achieving the perfect precision, the coefficient of the algorithm is optimised. The MATLAB is used to imitate the algorithm precision, and the effect of frequency excursion and direct current component. Come to light, the main touch contact resistance of HVCB is measured in off-line state. So it need the HVCB exited beforehand. Because of main touch contact resistance of HVCB. An indirect way for calculating main touchs temperature by using the breaker shell temperature,air circumference temperature by using the breaker shell temperature, air circumference temperature and breakers heat resistance is improved in this paper, and main touch resistance can be calculated if providing the load current. So it provides a thought for the on-line measuring the main touch resistance. In the hardware design, MSP430, a new Single Chip Microcomputer made by TI company , is engaged to develop the on-line monitoring system, and special problem brought by the lower supply voltagerange of this chip (1. 8~3. 6V) is considered fully. In the design of communication module, based on the special structure of MAX1480B, the RS-485 communication chips, the interfacing problem of different voltage chips MAX1480 andMSP430 is solved, and a connection scheme is given in this paper as well. For improving the real time performance, all the programs are realized by assemble language. In short, to improve the reliability of supply and distribution power, the work-state of power device must be known clearly, and on-line monitoring is an efficient way to know it. So it is a necessary trend and has a wide application to power system.