| 摘要 |
A remotely controlled electro-mechanical actuator, or a method of its operation, comprises charging a capacitor 17 from a power supply with a maximum supply current which is less than that required to drive the actuator 11. A public switched telephone network (PSTN) telephone line is used to provide the power and control signals. The capacitor 17 may have a capacitance of more than 1F or more than 5F with a leakage current of less than 50žA. A control signal may be used to switch between trickle charge and recharge modes to the capacitor 17. The actuator 11 may drive a hydraulic valve arrangement. The actuator 11 has a linear movement mechanism. This mechanism may include means of converting the rotary movement of a stepping motor into a liner movement. The telephone line input has a maximum power line supply current less than the required drive current of the linear actuator 11, and a leakage current of the capacitor 17 is less than the maximum allowed telephone line on-hook supply current. |
