Conveyor Lockout System with Location Identification
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Solution Overview
Problem
Conventional conveyor systems lack location information for activated emergency stop and remote isolation switches, leading to safety issues and inefficiencies in long installations due to electrical faults and power limitations, making it difficult to monitor operational parameters and maintain conveyor systems safely.
Innovation Solution
A conveyor monitoring system using pulse width modulation and amplitude modulation for communication between field devices and a central controller, combined with fail-safe redundant switching and a three-wire field bus system for accurate switch location identification and SIL 3 rating, providing both power and signaling on the same network.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If simple series connection of emergency stop switches is used, then the system structure is simple, but location information is not provided and safety is compromised
Solution Approach 1:
The conveyor system is divided into multiple zones with individual emergency stop switches at each zone. Each switch is equipped with a transmitter that provides location identification, allowing the control system to determine which specific zone triggered the emergency stop. This segmentation enables both simple installation and precise location tracking.
Solution Approach 2:
Transmitters and receivers are introduced as intermediary devices between the emergency stop switches and the control system. The transmitters send location-coded signals to receivers at the control panel, providing location information without complicating the basic switch installation. This intermediary layer bridges the gap between simple switches and the need for location data.
2Reliability
If end of line device is added to improve safety, then safety issues are addressed, but location information is still not provided
Solution Approach 1:
The emergency stop switches are designed to perform multiple functions: providing emergency stop capability, maintaining circuit integrity through end-of-line devices, and transmitting location information. Each switch assembly becomes a multi-functional unit that addresses safety requirements while simultaneously providing diagnostic location data.
3Device complexity
If power is provided only at drive points, then power distribution is simple, but monitoring systems cannot be installed along the entire conveyor length
Solution Approach 1:
The emergency stop switches are designed to be self-powered using power taken from the existing conveyor control circuit. Each switch draws minimal power locally to operate its transmitter, eliminating the need for separate power distribution along the conveyor length. This self-service approach enables monitoring capability without adding complex power infrastructure.
4Ease of manufacture
If conventional series connection system is used, then installation is simple, but the system is vulnerable to electrical faults from vibration, dust, and environmental factors
Solution Approach 1:
Redundant signaling paths and fault-tolerant circuit design are built into the emergency stop system before deployment. The transmitters use coded signals that can detect and report cable faults, allowing the system to identify and isolate problems before they compromise safety. This beforehand cushioning protects against the harsh mining environment.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables safe and efficient emergency stopping and remote isolation of conveyors, enhances system integrity and safety by providing location information for diagnostics, and reduces downtime through accurate switch location indication and fail-safe operations.
Implementation Method 1
pulse width modulation for communication between field devices and a central controller
Implementation Method 2
amplitude modulation for communication between field devices and a central controller
Data Source
AI summary
Lockout and monitoring system with SIL3 safety rating and method for lockout and monitoring of conveyor or any distributed plant are provided where pulse width modulation and amplitude modulation are used for communication between field devices (such as remote isolation switches deployed at various locations of a conveyor belt) and a central controller, and for indication of the device location. A fail safe redundant switching system for control circuit with additional transmitter and receiver modules are provided in combination with the means for accurate indication of switch location to achieve SIL 3 rating. The ability to provide control (analogue and digital outputs) for a distributed plant, for example along the length of a conveyor, is advantageously achieved, particularly when the control outputs are line powered by means of a field bus system that provides both power and signaling on the same network.