Development And Performance Testing Of Non-contact Voltage Sensing System

Voltage measurement is widely used in power transmission metering,household appliances and intelligent equipment control and other fields,which is an indispensable part of the process of scientific and technological development and progress,and with the further increase of people's demand for scientific and technological progress,the requirements for voltage measurement are also constantly improving.Most existing voltage measurement method for direct measurement,the measuring instrument access by measuring system for the extraction of signal,it can cause great influence to the original electronic system,the original system deviates from the original work status.The indirect method mainly include measuring voltage transformer,which can reduce the effects of the system to be measured,but is more used in high pressure environment,monitoring for high voltage transmission lines.So this paper put forward based on the principle of electric field coupling is suitable for contact on both ends of the voltage measuring contact resistance of non-contact voltage sensor,the system to be measured with a small disturbance,stable operation,small volume,high measuring precision,etc.Can be used in the railway switch machine within a narrow space under the contact at the ends of the voltage measuring contact resistance.For the development of non-contact voltage sensor,the main research contents of this paper are as follows:(1)An induction electrode structure with high voltage ratio suitable for the internal space of the switch machine is designed to ensure that the induction signals that meet the requirements can be collected to the maximum extent under the complex induction electric field.At the same time,the external high-frequency interference electrical signals should be shielded to obtain the voltage signals at both ends of the contact resistance with a frequency of 50 Hz that can accurately reflect the line voltage,so as to provide stable and strong enough induction signals for the subsequent signal processing.(2)Design and simulate the point machine contact group fault system,use the existing equipment in the laboratory to build a test platform,simulate the occurrence of various point machine contact group fault,and use the designed induction electrode that is the signal acquisition circuit to test the relevant simulation data.(3)High impedance subsequent processing circuit is designed,which includes the differential input impedance increase,such as second order bandpass filtering circuit to improve the clutter signal suppression and the extraction of the induction signal,to make sure not affect the sample link under the premise of the coupled signal acquisition and processing,and use the circuit simulation software to emulate the extraction of signal processing.(4)Integrated signal acquisition system is designed,which includes sensing electrode,processing circuit,converting circuit,the stability of contact voltage measurement system,carries on the PCB design and production,the measurement system of physical PCB integration with the front electrode,and the test platform to repeat the test and calibration of system,by adjusting the output precision resistance box resistance to simulate a switch contact resistance change,can produce is suitable for the field environment of noninvasive voltage measurement system.