| 摘要 |
An electrohydraulic drive mechanism for the isolator in a sectioning point for high voltage comprises a reversible pump 11, the connections of which are coupled via a pair of pressure-regulated check valves 18 to a bilateral manoeuvring device, such as opposite connections of the hydraulic cylinder 16. Both the feed lines comprise large- volume expansion vessels 13, 14. In the rest position, the check valve pair 18 locks the manoeuvring member 16 and, when the pump 11 starts up, the suction-side expansion vessel feeds the pump until its return-side check valve on the same side is opened. The opening pressure of the check valves 18 is set high, to at least 30% of the maximum pressure of the system, and at least one of the said check valves has a strong hysteresis, i.e. it stays in the open position when the pressure drops, the pump 11 first feeding the pressure-side expansion vessel until the opening pressure of its return- side check valve is exceeded, whereupon, when the resistance falls as the manoeuvring device sets itself in motion, the expansion vessel feeds the manoeuvring device in addition to the pump 11 and instantaneously produces a large volume flow. <IMAGE>
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