Contactor Wear Tracking via Current Mapping
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Solution Overview
Problem
Existing methods for estimating the degradation of electronically controlled electro-mechanical switches, such as contactors, are unreliable and difficult to quantify, leading to potential unsafe operation or system failure due to cumulative damage from current arcing during make and break cycles.
Innovation Solution
A method and system that determine the change of state of a contactor, compute wear increments using a mapping between measured current and wear coefficients, and accumulate wear over successive changes to predict contactor degradation, with optional features like periodic monitoring, voltage scaling, and threshold comparison for raising alarms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If direct measurement methods (impedance or voltage across contacts) are used to estimate contactor wear, then measurement precision may be improved, but system safety deteriorates due to risks associated with high voltages
Solution Approach 1:
The patent uses current measurements as an intermediary parameter to indirectly assess contactor wear without requiring direct contact with high voltage points. The controller monitors current through the contactor and uses this safe, accessible measurement to infer wear state, avoiding the need to measure impedance or voltage across the contacts directly.
Solution Approach 2:
The patent replaces direct electrical measurement methods (which require physical contact with high voltage components) with a control system-based approach using current monitoring. This substitutes a dangerous mechanical/electrical measurement process with a safer electronic control and calculation process.
2Reliability
If contactor replacement is planned based on manufacturer ratings, then system reliability is improved, but productivity deteriorates due to scheduled downtime
Solution Approach 1:
The patent implements preliminary monitoring and assessment of contactor wear through current measurements and calculations. By detecting wear trends before the contactor actually fails, the system can plan maintenance at optimal times rather than relying on conservative scheduled replacements, thus maintaining reliability while minimizing unplanned downtime.
Solution Approach 2:
The patent establishes a feedback loop where the controller continuously monitors current, calculates wear indicators, and uses this information to assess contactor health in real-time. This feedback enables dynamic maintenance planning based on actual wear conditions rather than static manufacturer ratings, optimizing both reliability and productivity.
3Reliability
If cumulative wear is not tracked, then device complexity is reduced, but reliability deteriorates due to inability to predict contactor failure
Solution Approach 1:
The patent makes the existing controller perform multiple functions: it not only controls the contactor but also monitors current, calculates wear indicators, and assesses contactor health. By adding these analytical capabilities to the existing control device, the system achieves wear tracking without adding separate dedicated hardware, thus limiting the increase in overall system complexity.
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
This approach improves system reliability and safety by accurately tracking contactor wear, allowing for timely maintenance and preventing failures, thus ensuring the contactor's ability to safely operate and disconnect energy storage systems.
Implementation Method 1
Contactors are devices capable of conducting the energy in the system and interrupting that current as required
Implementation Method 2
This damage is due to arcing which occurs between the contacts of the contactor while it is transitioning between closed and open states
Data Source
AI summary
The present invention is notably directed to methods for estimating a degradation of an electronically controlled electro-mechanical switch. The methods comprise determining a change of state of the contactor. They also comprise, computing, for each determined change of state, a wear increment WI of the contactor by: identifying a wear coefficient using a mapping between a last measured current through the contactor and a current range associated with a given wear coefficient; computing the actual wear WN of the contactor by adding the computed wear increment WI to a former known wear WI−1 of the contactor.