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ELEVATOR WITH SAFETY CHAIN OVERLAY CONTROL UNIT COMPRISING A SAFETY PLC SEPARATELY MONITORING VARIOUS SAFETY SWITCHES FOR INCREASING A SAFETY INTEGRITY LEVEL
ELEVATOR WITH SAFETY CHAIN OVERLAY CONTROL UNIT COMPRISING A SAFETY PLC SEPARATELY MONITORING VARIOUS SAFETY SWITCHES FOR INCREASING A SAFETY INTEGRITY LEVEL
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机译:带有安全链叠加控制单元的电梯,包括安全PLC,分别监视各种安全开关,以提高安全完整性
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摘要
An elevator has a drive unit displacing an elevator car in an elevator hoistway, an elevator controller controlling operation of the drive unit, multiple safety switches switchable upon occurrence of safety relevant events, and a safety chain overlay control unit including a safety PLC. The PLC has first connectors connected to first safety switch contacts and second connectors connected to second safety switch contacts. The PLC monitors a current safety status of the elevator and identifies a safety critical status by detecting when at least one of the safety switches changes its switching state and comparing the current switching states of the first and second safety switches. The PLC interrupts a main energy supply to the drive unit in response to the safety critical status of the elevator. Comparing switching states of the safety switches connected to the first and second connectors also enables detecting faulty safety switches.
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