Power circuit breakers, which are essential to protect electric power equipment and are required to operate at high speed, are usually driven by hydraulic control systems.
The present paper deals with numerical simulation as well as experimental examination of such a system composed of a spool-type 2-position 3-way directional control valve and a cylinder actuated by it. The conventionally used directional valve, in which a spool with two poppet-like collars works to switch the flow direction, has been found incapable of driving the piston fast enough. Numerical simulation of the system's performance predicts that this is caused by the structure of the valve, which allows both high and low pressure ports to be open during the switching motion. A new directional valve designed to avoid this defect was introduced to take the place of the conventional one, to greatly improve the response of the circuit breaker.
