Redundant safety circuit

Abstract

In modern elevators, safety circuits are used for preventing the operation of an elevator having possibly safety related problems. Sometimes the problem is in the safety circuit itself, and the operation could be continued. In a disclosed arrangement, groups of at least two independent safety circuits are used. The operation of the elevator can be continued in the case where one safety circuit in each group indicates that there is a possible problem. Thus, one deficient safety switch in one safety circuit does not prevent the operation.

Dependencies are inferred from the claim text.