Method and system for continuous condition monitoring of hoist chains

A method for continuous condition monitoring of a hoist chain comprising the steps of

• a) detecting with a first sensor a presence and an absence of chain links,
• a′) detecting with a second sensor a presence and an absence of teeth of a chain sprocket or the presence and the absence of chain links,
• b′) determining with an evaluation unit, using a signal obtained from the first sensor, a first time interval reflecting the presence of a first chain link and a second time interval reflecting the absence of chain link between the first chain link and a third chain link,
• b″) determining with the evaluation unit, using a signal obtained from the second sensor, a third time interval reflecting the presence of a first tooth or the presence of the first chain link or a second chain link or the third chain link and a fourth time interval reflecting the absence of tooth between the first tooth and a second tooth or the absence of chain link between the first chain link and the third chain link or between the second chain link and a fourth chain link or between the third chain link and a fifth chain link,
• c) determining with the evaluation unit a first sum of the first time interval and the second time interval as well as a second sum of the third time interval and the fourth time interval,
• d) determining with the evaluation unit a chain speed, and
• e) comparing with the evaluation unit the first sum with the second sum in order to determine an elongation of the hoist chain, wherein each time interval was determined at the same chain speed.