| 摘要 |
The object is to compensate for an interruption in, or failure of, the speed signal in such a way that a motor overspeed is avoided. The tachogenerator (G) driven by the motor is connected via two leads (1, 2) to the speed controlling circuitry (3) which has a high input impedance. A stabilized voltage source (E) is connected across the tachogenerator with an ohmic value resistor (4) in series. As long as the tachogenerator circuit is complete the proportion of the voltage (E) dropped across it is small since the circuit is of low impedance. If the circuit is broken the resistor (4) is in series with the controller (3) input and a large voltage appears across the input in consequence thus reducing the motor speed virtually to zero. |
