Regular maintenance of density relays which monitors SF

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gas density in real time is an important guarantee to ensure safe operation of power equipment system. For obtaining the accurate value of SF

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gas density under different conditions

in this paper a kind of mature and reliable numerical calculation method for SF

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density is proposed based on the statistics of actual measurement data in industrial sites. In view of such disadvantages as large volume and large random error of SF

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density relay calibration instrument in regular maintenance

a lightweight built-in cylinder design is proposed

supplemented by statistical processing of upper computer software

which improves the calibration accuracy of SF

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density relay system. For reducing the manpower and material resources of regular maintenance and improving the maintenance efficiency of density relay

a networkable and lightweight CPU less intelligent online gas density detection device based on field bus is further proposed by integrating the above results. The corresponding lightweight measurement and control module and collaborative real-time monitoring software are developed and the demonstration application is performed in practice. The practice results show that the system

on the basis of ensuring measurement accuracy

saves maintenance workload

has high reliability and achieves the automation of maintenance process and result management.