Comprising an electric transmission mechanism, a switch body, and an electric controller, this series is suitable for oil-immersed transformers with a maximum equipment voltage of 40.5 kV or lower and a rated current of 630A or lower. The tap and switch operations can be performed electrically or manually in the de-energized state. It is designed to be used with our electric controller JLK-718A, and it is essential to ensure that the transformer is de-energized before operating.