| 摘要 |
A manual drive for the step-by-step operation of an off-load tap changer for tapped transformers having a drive shaft which can be operated by means of a hand crank and having an output drive shaft which can be coupled to the off-load tap changer shaft and carries out one revolution per switching step. A housing contains a step-up transmission (which is located between the drive shaft and the output drive shaft) and a switching position indicator which can be observed by means of a viewing window and has a numerical scale which has a numerical sequence, distributed uniformly, corresponding to the number of switching positions. The step-up ratio is n (1)/z:1, where n is the number of complete revolutions to be carried out per switch operation by the hand crank and z is the number of switch positions of the off-load tap changer. The numerical scale is connected directly to the drive shaft and, furthermore, a covering disc, which is located between the viewing window and the numerical scale, is coupled to the output drive shaft, which covering disc has a recess which corresponds to the viewing window and is arranged such that the viewing window is exposed when the off-load tap changer is in the quiescent position.
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