Elevator having a safety chain with a series connection of safety switch arrangements

摘要

The invention relates to an elevator having a safety controller (10) with a safety chain (18) comprising several safety switch arrangements (20 - 28). The safety controller is configured to cause the stop of the elevator motor (14) and the activation of the motor brakes (16). At least one of said safety switch arrangements comprises at least one first resistor (38) connected in series with a safety switch (36). In the safety controller (10) a comparator (32) is provided for the determination of the status of the safety chain, which comparator is connected with a memory (34) for storing at least one resistor reference value. The comparator is configured to output a safety chain status signal in dependence of comparison of the measured resistance value with the resistor reference value. The invention allows the detection of a short circuit as well as of the opening of a safety switch arrangement.