The speed characteristics during opening and closing operation are important characteristic parameters ofhigh voltage circuit breaker

which affect the working performance of circuit breaker directly. It is always difficult tomount a displacement transducer or angle sensor into a high voltage circuit breaker online. Besides

the sensors andits attachments always take negative impact on the mechanical characteristics of circuit breaker. Aiming at solvingthose problems

this paper developed a speed characteristics measuring method based on machine vision algorithm.This non-invasive method only needs to set some color marks on the surface of some moving parts as the movementreference points whose movement keep in accordance with the moving contacts of circuit breaker. The moving tracksof reference marks are automatically identified through processing the video of circuit breaker operation recorded byhigh speed camera.Then the speed characteristics of moving contact can be obtained

based on machine vision algo-rithm. Experiments have been carried out with a 12kV vacuum circuit breaker

the result shows that the characteris-tic curve measured by this method is precise compared with high accuracy displacement sensor and it meets the re-quirement of speed characteristic detection. Moreover

this method doesn’t require any additional fixtures and ismore convenient for on-site measurement than traditional measuring method

without the necessity for high voltageisolation.