Method for preventive maintenance of elevator and elevator system

The invention relates to 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 comprises: determining a reference distance for an elevator car travel between a first door zone and a second door zone, during the elevator car travel, defining continuously a first elevator car speed information from the first sensor and a second elevator car speed information from the second sensor, calculating a cumulative sensor system error by integrating the 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. 本发明涉及一种用于电梯速度传感器系统的预防性维护的方法，该电梯速度传感器系统包括至少彼此独立的第一和第二传感器。该方法包括：确定电梯轿厢在第一门区域和第二门区域之间行进的参考距离，在电梯轿厢行进期间，连续地定义来自第一传感器的第一电梯轿厢速度信息和来自第二传感器的第二电梯轿厢速度信息，通过对第一电梯轿厢速度信息和第二电梯轿厢速度信息之间的差值进行积分来计算累积传感器系统误差，并将累积传感器系统误差除以参考距离来获得传感器系统性能指标。