TWO-STAGE VALVE ARRANGEMENT FOR HYDRAULIC CONTROL OF A PISTON-CYLINDER ARRANGEMENT OF A HIGH- OR MEDIUM-VOLTAGE POWER SWITCH

A valve arrangement for hydraulic control of a piston-cylinder of a power switch (7) contains a main stage having a first main valve (31) and a second main valve (32), and a pilot stage having at least one pilot valve (3, 4). In order to permit the first main valve (31) to remain securely in the opened state, even in the event of pressure oscillations, the main valve has a total of four control surfaces, of which a second (F5) and a third (F6) control surface operate in a closing manner and a fourth control surface (F7) operates in an opening manner. For this purpose, the second control surface (F5) is connected to the high-pressure line (P), the third control surface (F6) is connected to the low-pressure line (T), and the fourth control surface (F7) is connected to the output-side valve connection (35) of the first main valve (31). The size ratio of the opening control surfaces (F4, F7) to the closing control surfaces (F5, F6) is selected such that in the open condition of the first main valve (31) an openin