Patent ID: 10099897

Abstract:
An elevator has a safety controller to which several safety switch arrangements are connected. The safety controller is configured to cause the stop of the elevator motor and the activation of the motor brakes. A comparator is provided in the safety controller for the determination of the status of the safety chain. The comparator is connected with a memory for storing at least one resistor reference value, which comparator is configured to output a safety chain status signal in dependence of comparison of a measured resistance value with the resistor reference value. Each of said safety switch arrangements includes at least one first resistor and a safety switch which are connected in series. The value of the first resistor is different in at least some safety switch arrangements, preferably in all safety switch arrangements. Each safety switch arrangement includes at least a second resistor connected in parallel with the safety switch, which second resistor has a higher value than the first resistor. The detection of a short circuit as well as of the opening of a safety switch arrangement are allowed.