高温环境下数字反应性仪微电流测控技术可靠性研究

Research on Reliability of Micro Current Measurement and Control Technology of Digital Reactivity Instrument Under High Temperature Environment

数字反应性仪是核电厂用于测量反应性的专用设备,能够实现宽范围的微电流测量,采用高精度驱动电路控制电磁继电器实现电流范围自动量程切换是本设备的关键技术之一。在高温环境下,继电器会出现线圈阻值变化而导致驱动电压需求增大的现象,进而导致继电器可靠性降低。为提高高温环境下微电流测控技术可靠性,重点开展不同继电器驱动方式对高温环境下数字反应性仪微电流测控技术可靠性研究。研究发现,相对于低电平驱动模式,高电平驱动模式能够有效提高高温环境下反应性仪微电流测控电路可靠性。通过高温步进试验验证,该数字反应性仪在65℃环境下,达到热平衡后的30 min内,微电流测量稳定有效。

Digital reactivity meter is a special equipment for measuring reactivity in nuclear power plant,which can realize a wide range of micro current measurement.It is one of the key technologies of the equipment to use high-precision driving circuit to control electromagnetic relay to realize automatic range switching of current range.In high temperature environment,the relay will have the phenomenon that the change of coil resistance value will lead to the increase of driving voltage demand,which will lead to the decrease of relay reliability.In order to improve the reliability of microcurrent measurement and control technology in high temperature environment,this paper focuses on the reliability reassure of microcurrent measurement and control technology of digital reactivity instrument in high temperature environment with different relay driving modes.It is found that compared with low level driving mode,high level driving mode can effectively improve the reliability of micro current measurement and control circuit of reactivity instrument under high temperature environment.The results of high temperature step test show the digital reactivity meter is stable and effective in micro current measurement within 30 min after reaching thermal equilibrium at 65℃.