Contactor Fuse Condition Diagnosis via Pilot Current Injection
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Solution Overview
Problem
Existing devices for determining the condition of contacts in contactors or fuses face issues with indeterminate states, floating potentials, and complexity due to high voltage requirements, leading to uncertain current flow detection and cumbersome circuit designs.
Innovation Solution
A device comprising a current generator to deliver a pilot current and a computing/electronic module that verifies the flow of this current through the contact, using a transformer for isolation and a microcontroller for impedance assessment, allowing determination of contact conditions regardless of electrical potential, simplifying the diagnosis process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If potential measurement is used to determine contact condition, then the measurement range can be adjusted for high-voltage circuits, but the device complexity increases due to required isolation circuits and disconnect switches
Solution Approach 1:
The patent introduces a current generator as an intermediary device that injects a test current through the contact to be diagnosed. This current generator acts as a mediator between the measurement circuit and the high-voltage contact, eliminating the need for complex isolation circuits and disconnect switches while enabling accurate contact condition detection through current flow measurement rather than potential measurement.
2Measurement precision
If potential measurement is used to detect contact condition, then the contact state can be determined, but indeterminate conditions and floating potentials lead to uncertain detection
Solution Approach 1:
The patent employs a self-service approach by having the contact under test actually carry the test current injected by the current generator. This allows the contact to actively participate in the measurement process, providing unambiguous current flow information that eliminates indeterminate states and floating potential issues, thereby ensuring reliable and certain detection of contact condition.
3Adaptability or versatility
If the contact to be diagnosed is connected to different electrical potentials than the measuring circuit, then high voltage potentials can be measured, but isolation circuits are required increasing device complexity
Solution Approach 1:
The current generator serves as an intermediary that can operate at different electrical potentials than the measuring circuit. It injects test current through the contact regardless of the contact's connection to high voltage potentials, enabling the system to adapt to various voltage conditions without requiring complex isolation circuits for each measurement scenario.
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 accurate detection of contact conditions without relying on potential references, allowing for pre-service diagnosis and simplifying circuitry, reducing complexity and uncertainty in high voltage environments.
Implementation Method 1
The current generator is arranged such that the supply of the pilot current reflected at the primary side of a transformer is suitably isolated from the supply of main current to the fuse or contact
Data Source
Figure 1~2
AI summary
The device (100) comprises an current generator (50) adapted to deliver a pilot current (P) through the fuse or contact (10) to be diagnosed, and a computing/electronic module for verifying if the delivered pilot current (P) flows through the fuse or contact (10). The computing/electronic module comprises a transformer (T1) for separating potentials between the fuse or contact (10) to be diagnosed and the computing/electronic module, transistors (Q1, Q2) provided in the primary windings of the transformer (T1), and condensers (C1, C2) provided in the secondary windings of the transformer (T1).