Down-Hole Harness Current Limiting for Detonator Leakage Faults
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Solution Overview
Problem
Electronic blasting systems face issues with undesirable leakage currents, which can lead to catastrophic short circuits, misfires, and significant financial losses due to voltage starvation, especially when failures occur after mining equipment and personnel have been evacuated, and the system is not designed to efficiently identify or mitigate these issues in real-time.
Innovation Solution
Incorporating current-limiting components, specifically resistors, in series with the down-hole harnesses to limit current flow to a predetermined level that the blasting control machine can accommodate, thereby preventing voltage starvation and allowing the blasting system to continue operation even with faulty detonators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If tantalum capacitors are used to ensure autonomous operation, then reliability is improved, but the risk of catastrophic short-circuit failure increases
Solution Approach 1:
A current-limiting resistor is connected in series with the capacitor to pre-establish protection against short-circuit failures. This resistor limits the maximum current that can flow through the capacitor, preventing catastrophic failures while maintaining the capacitor's ability to provide autonomous operation functionality.
Solution Approach 2:
The current-limiting resistor acts as an intermediary element between the power source and the capacitor. It mediates the current flow, allowing the capacitor to function reliably for autonomous operation while preventing harmful short-circuit currents from reaching dangerous levels.
2Device complexity
If detonators are connected in parallel to share a wire bus, then system complexity is reduced, but voltage starvation and misfire risks increase due to leakage currents
Solution Approach 1:
The blasting system is segmented into multiple independent groups, with each group having its own current-limiting resistor. This segmentation isolates leakage current problems to individual groups, preventing voltage starvation from affecting the entire system. Each segment can operate independently, maintaining reliability while using a simple parallel bus structure.
3Productivity
If voltage is raised to blasting level before evacuation, then productivity is improved, but the risk of catastrophic failure increases
Solution Approach 1:
Current-limiting resistors are installed in advance as a protective measure before voltage is raised to blasting levels. These resistors cushion against potential short-circuit failures, allowing the system to operate at full blasting voltage with reduced risk. This enables productivity improvement while maintaining safety through pre-established current protection.
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
The solution effectively limits the impact of leakage currents, allowing the blasting system to function without major disruptions, even when faults occur, by maintaining sufficient voltage for operational detonators and minimizing the risk of misfires, thus reducing financial losses and operational delays.
Implementation Method 1
at least one current-limiting component which is connected in series with the respective down-hole harness and which is configured to limit the current in the down-hole harness
Data Source
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AI summary
A detonator system wherein a detonator is connected via a down-hole harness to a bus extending from a blast controller and wherein a component is connected in series with the down-hole harness to limit leakage current in the harness to a level which can be accommodated by the blast controller.