CPC B66B 5/0025 (2013.01) [B66B 5/0031 (2013.01); B66B 5/0037 (2013.01)] | 20 Claims |
1. A method for preventive maintenance of an elevator speed sensor system comprising at least a first and a second sensor, which are independent of each other, the method comprising:
determining a reference distance for an elevator car travel between a first door zone and a second door zone;
during an elevator car travel between the first door zone and the second door zone, defining continuously first elevator car speed information from the first sensor and second elevator car speed information from the second sensor;
calculating a cumulative sensor system error by integrating a difference between the first elevator car speed information and the second elevator car speed information; and
dividing the cumulative sensor system error with the reference distance to obtain a sensor system performance indicator.
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