| 摘要 |
A control circuit for controlling the operation of an electromagnetic device consisting of a solenoid (12) and an armature comprises a transistor switch (13) which is connected in series with the solenoid (12) and DC supply terminals (10, 11), a Zener diode (16) which is connected in parallel with the transistor switch (13), and a solid-state switching device (14, 15) which is provided in parallel with the solenoid (12). The operation of the solid-state switching device (14, 15) and of the transistor switch (13) is controlled by a control circuit (17). The transistor switch (13) is opened and the switching device (14, 15) is closed in order to maintain the current flow in the solenoid (12), the transistor switch (17) being pulsed in order to maintain a mean current flow. When it is intended to deenergise the solenoid (12), the transistor switch (13) and the switching device (14, 15) are both opened and the Zener diode (16) conducts in order to protect the transistor switch (13) against a high voltage which is induced in the solenoid (12), and in order to consume the stored energy of the magnetic circuit of the solenoid (12). <IMAGE> |
