Safety Chain Circuit Amplifier for Elevator Hoistway
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Solution Overview
Problem
Long transmission paths in safety chain circuits for elevator systems require large and variable power supplies due to multiple relay configurations, leading to inefficiencies and limitations in system design, particularly in longer hoistways.
Innovation Solution
A safety chain circuit with an amplifier that includes enabling and control switches, monitor switches, and a safety chain monitor, allowing for independent control and monitoring of the circuit status, reducing power variability and enabling consistent power draw, and allowing for longer low-voltage safety chain utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the safety chain runs the entire length of the hoistway multiple times to provide adequate protection coverage, then the safety coverage and reliability are improved, but the transmission path length increases and requires a larger power supply
Solution Approach 1:
The safety chain circuit is divided into multiple segments, each served by its own amplifier. The amplifiers are distributed along the hoistway at strategic locations, creating segmented zones that each receive localized amplification. This segmentation allows the system to maintain adequate safety coverage across long distances without requiring a single excessively long transmission path from a centralized power source.
Solution Approach 2:
Amplifiers are introduced as intermediary devices between the power source and the distributed protection devices. These amplifiers receive signals from the safety chain, amplify them, and re-transmit them further along the chain. This intermediary function allows the system to extend its reach across long hoistways while maintaining signal integrity and reducing the burden on the main power supply.
2Reliability
If multiple relay configurations are used to ensure adequate protection throughout the hoistway, then the safety reliability is improved, but the power supply size and complexity increase
Solution Approach 1:
The power supply system is segmented into multiple independent amplifier units distributed along the hoistway. Each amplifier is a self-contained module that can be independently configured and maintained. This segmentation reduces the complexity of the overall power supply system compared to a single large centralized power supply, as each amplifier handles only a local segment of the safety chain.
Solution Approach 2:
The amplifiers are designed as universal, multi-functional devices that can serve multiple protection devices within their zone. Each amplifier can handle various types of protection devices (door locks, emergency switches, overspeed devices, etc.) and can be configured for different hoistway requirements. This universality reduces the need for specialized power supply configurations for different device types.
3Adaptability or versatility
If the safety chain is extended to cover longer hoistways, then the adaptability to different installation scenarios is improved, but the power supply requirements become more stringent
Solution Approach 1:
The system employs dynamic signal amplification where amplifiers actively boost signals as they propagate along the safety chain. This dynamic amplification allows the system to adapt to longer transmission distances by compensating for signal attenuation in real-time. The amplifiers can be adjusted or configured to provide appropriate gain levels based on the specific hoistway length and requirements.
Solution Approach 2:
Distributed amplifiers act as intermediary signal boosters that extend the effective range of the safety chain without requiring a proportional increase in the main power supply capacity. Each amplifier receives the incoming signal, amplifies it to a standardized level, and passes it along, effectively extending the system's reach while maintaining consistent power levels throughout the chain.
Data Source
AI summary
A safety chain circuit includes a plurality of protection devices connected between a first chain end and a second chain end, and an amplifier. The amplifier includes a first device switch and a second device switch connected between an input and an output, a first enabling switch connected between the second chain end and a second enabling switch, and a first control switch and a second control switch. The first enabling switch selectively enables the first control switch to control the first device switch. The second enabling switch selectively enables the second control switch to control the second device switch. The first control switch, when enabled, selectively controls the first device switch in response to receiving a first control signal. The second control switch, when enabled, selectively controls the second device switch in response to receiving a second control signal.