Relay Coil Inductance Detection for Welded Contacts
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Switching devices with welded or partially welded contacts pose electrical and mechanical safety issues due to their inability to disconnect electric power from loads, as the contacts become stuck in a closed state, preventing proper operation and maintenance.
Innovation Solution
A method to detect welded contacts in switching devices by pinging the relay coil with a non-intrusive voltage or current pulse, measuring the coil's inductance, and determining the presence of welded contacts without powering the device or relying on sensors, allowing for preventative action to avoid safety issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional sensing methods with sensors are used to detect welded contacts, then detection capability is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces physical sensors and mechanical detection systems with an electrical measurement approach. By measuring the coil's inductance through voltage and current measurements during coil activation, the system detects welded contacts without requiring additional sensors or complex mechanical detection mechanisms. This substitution reduces device complexity while maintaining detection capability.
Solution Approach 2:
The system uses the coil's own electrical characteristics (inductance) during normal operation to detect welded contacts. The control circuit measures voltage and current already present in the coil circuit, eliminating the need for separate detection systems. The coil essentially detects its own welded state through its electrical properties, reducing overall system complexity.
2Measurement precision
If intrusive sensing methods are used to detect welded contacts, then detection accuracy is improved, but safety risks and device damage increase
Solution Approach 1:
The patent replaces intrusive physical sensing methods with non-intrusive electrical measurements. By measuring voltage and current during normal coil activation and calculating inductance from these measurements, the system detects welded contacts without introducing additional electrical stress or physical intrusion that could cause safety issues or damage the device.
Solution Approach 2:
The patent uses inductance as an intermediary parameter to detect welded contacts indirectly. Rather than directly sensing the welded contact state through intrusive means, the system measures electrical parameters (voltage and current) and calculates inductance, which reflects the contact state. This indirect measurement approach reduces safety risks while maintaining detection accuracy.
3Reliability
If continuous monitoring is implemented to detect welded contacts, then reliability is improved, but energy consumption increases
Solution Approach 1:
The patent implements periodic monitoring by measuring coil inductance during normal activation cycles rather than continuous monitoring. The control circuit measures voltage and current when the coil is activated, calculating inductance at these periodic intervals. This approach maintains reliability by detecting welded contacts during regular operations while minimizing energy consumption by not continuously monitoring.
Solution Approach 2:
The system performs detection during normal coil activation periods, utilizing existing operational cycles. By measuring inductance during each activation event, the system continuously monitors for welded contacts using the same useful action (coil activation) already required for device operation, avoiding additional energy-consuming separate monitoring cycles.
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 the detection of welded contacts in a non-intrusive manner, reducing electrical and mechanical safety risks and improving relay device performance by preventing stuck conditions, thus ensuring reliable operation and maintenance.
Implementation Method 1
A relay device includes a relay coil configured to receive a driving voltage
Implementation Method 2
measuring the coil's inductance
Data Source
Figure 1~3
Figure 4
Figure 5
AI summary
A non-transitory, computer-readable medium may include instructions executable by at least one processor in a computing device to cause the processor to perform operations that include transmitting, to a first power source, a command to provide power to a coil of a switching device with a fixed current profile. The operations also include receiving one or more voltage measurements associated with the coil during a period of time, determining whether the voltage measurements associated with the coil indicate that one or more movable contacts of the switching device are at least partially welded to one or more contacts of an electric circuit, and transmitting an additional command to a second power source to disconnect a current to the coil in response to determining that the voltage measurements indicate that the movable contacts of the switching device are at least partially welded to the contacts of the electric circuit.