1. Use an electromagnetic oscillator or a drum recorder. In early oil switch characteristic tests, an electromagnetic oscillator was connected to a pencil fixed on the moving contact rod to drive it to move horizontally at a frequency of 100Hz during the switch closing process. As the rod moved, an oscillation wave of travel time was drawn on a fixed cardboard with coordinates. The principle is to design the drum surface so that each 1mm of rotation corresponds to 1ms of time. During measurement, the switch contacts drive the recording pen to move up and down, drawing the closing or opening curve. The markers used in these two methods essentially act as displacement sensors, characterized by simplicity and convenience, but they are susceptible to various factors, easily causing significant measurement errors.
2. Use a slide wire rheostat with an oscilloscope for characteristic testing. The rheostat consists of a wire-wound resistor and a sliding contact. The sliding contact is fixed to the moving contact rod. A constant voltage is applied across the resistor. As the moving contact rod moves, the voltage waveform across the sliding resistance is recorded with an oscilloscope to obtain travel time curves and related speed data. The disadvantage of this method is that adjustment is difficult, and it lacks sufficient support for extended analysis of the mechanical performance curves.
3. Use a grating displacement sensor (grating ruler) as a displacement sensor for intelligent comprehensive analysis and testing management. With the continuous advancement of computer information technology and sensor network technology, circuit breaker mechanical characteristic testing systems have gradually developed into intelligent, digital, and graphical comprehensive testing tools. At this time, temperature sensors also mostly adopted grating rulers. A grating ruler typically uses gratings engraved on a certain medium (such as glass, crystalline ceramics, or steel strips) as a measurement reference. Its basic working principle is to use photoelectric cells that sense light intensity changes for scanning to perform measurement. Grating rulers have strong anti-interference and high sensitivity, but they are prone to damage during actual testing or storage. Many users have gradually switched to linear or angle sensors.
4. Currently, using linear sensors (slide wire rheostats) or angle sensors (angular potentiometers) in conjunction with microprocessor-based switch characteristic testers for intelligent characteristic detection has become a popular testing method, and its testing is far superior to non-electrical sensors in early stages.
