| 摘要 |
The system is for use on alternating-current hoist and travel motors, having a frequency measuring unit monitoring the slip frequency in several stages and switching the starting resistances in and out dependent on this frequency. The stages of the starting resistance for hoisting and lowering are divided into further partial resistances, each of which corresponds to a measuring stage of the frequency measuring unit. These are switched in and out by the measuring unit when rotor frequency reaches the value at which the respective measuring stage functions. Three measuring stages can be provided in the frequency monitoring unit, the values at which they function being adjustable by the command unit determining the starting stages. |
