Abstract: Operation of a medium voltage spring powered circuit breaker is analyzed by applying a recording medium in the form of an adhesive backed tape to a selected driven part of the operating mechanism. A marking instrument is held in contact with the recording medium at a fixed point by a fixture in the form of a template secured to the circuit breaker frame. When the charged closing springs of the operating mechanism are released, the marking instrument produces a trace on the recording medium which is then analyzed to provide a quantitative evaluation of switch operation, including overtravel of the selected driven part.