| 摘要 |
<p>The holding force of the d.c. electromagnet is reduced after a preset period to a defined ratio of its attractive force by a series-connected resistor (2), behind which is a parallel connected capacitor (1). Preferably the capacitor and resistor, and possibly a bridge rectifier are assembled to form a four-pole module. The typical application is for electromagnetic valves whose coils generate a considerable amount of heat. This disadvantage is removed by the reduction of current, produced by the incorporated resistor so that the controlled liquid is not heated by the hot valve coil.</p> |
