Relay Coil Inductance Monitoring for Weld Fault Detection
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Solution Overview
Problem
Existing relay monitoring solutions are bulky and interfere with relay operation, failing to safely and simply detect welding faults between contact bridges and stationary contacts due to overcurrents.
Innovation Solution
A compact relay assembly with an inductance measurement device connected via a capacitor, allowing status monitoring only in a non-energized state, using a common ground and oscillator to measure inductance without additional devices, and transmitting results via a signal pin, which can be integrated into the relay's control circuit or housed within the relay.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional measurement devices are added to monitor relay status, then fault detection capability is improved, but device complexity and size increase
Solution Approach 1:
The relay's existing coil serves dual purposes: its primary function for actuation and its secondary function as the measurement object for inductance-based status monitoring. By measuring the coil's inductance through the capacitor connection, the system uses the relay's own components for self-diagnosis, eliminating the need for separate measurement devices and reducing overall device complexity while maintaining fault detection capability
Solution Approach 2:
The coil is assigned multiple functions: it acts as both the actuating element for relay operation and the measurement target for status monitoring. The same physical component (coil) serves both operational and diagnostic purposes, reducing the total number of components needed in the system
2Reliability
If continuous monitoring is performed during relay operation, then real-time status detection is improved, but interference with relay operation occurs
Solution Approach 1:
The system performs inductance measurements only during the non-energized state of the relay, rather than continuously during operation. The capacitor enables periodic sampling of the coil's inductance state when the relay is de-energized, providing status information without interfering with the relay's normal energized operation. This periodic measurement approach balances real-time monitoring needs with operational integrity
3Ease of operation
If a capacitor is used to decouple the measurement circuit, then non-intrusive monitoring is achieved, but measurement frequency is limited
Solution Approach 1:
The capacitor acts as an intermediary element that couples the measurement circuit to the coil during the non-energized state. It enables the measurement of inductance changes that indicate armature position or welding faults without directly interfering with the relay's operational circuit. The capacitor's decoupling effect allows safe, non-intrusive monitoring while accepting that measurements can only be performed during specific operational windows
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, simple, and non-intrusive monitoring of relay status, distinguishing between normal and fault states without interfering with relay operation, and can be easily integrated into existing systems, providing accurate fault detection with minimal space and complexity.
Implementation Method 1
The capacitor can thus achieve a good decoupling, resulting in a safe and simple operation
Implementation Method 2
the relay having an armature and a coil for moving the armature
Implementation Method 3
the inductance of the coil is determined by measuring the phase angle
Data Source
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AI summary
The invention relates to an assembly (100) for monitoring the status of a relay (200) having an armature (210) and a coil (220) for moving the armature (210), wherein the assembly (100) comprises an inductance measurement device adapted for measuring the inductance of the coil (220), and a method of monitoring the status of a relay (200) having an armature (210) and a coil (220) for moving the armature (210), wherein an inductance of the coil (220) is measured.