a hydraulic elevator recently modernized with a new MCE controller. The
graphs show blue bars for accelerations, and yellow when the
door is open. A normal trip consists of one pair of accelerations in
opposite directions, followed by the door opening for 6 seconds.
Over the course of several months,
there were a few occasions where the elevator repeatedly moved up,
sat for 5 seconds without opening the door, moved down, and opened
the door for 40 seconds. This continued for 1 to 2 hours!
problem was diagnosed as a bad floor sensor. The car was moving up
and down trying to find the top and bottom floors. No one knew this
was happening until QarVision was installed.
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