Relay Unit Normally Closed Contact False Assessment Reduction
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Solution Overview
Problem
Normally closed contacts in relay units are often misassessed as abnormal due to temporary or recoverable factors during monitoring, such as vibrations or foreign particle intrusion, when the load is de-energized.
Innovation Solution
A relay unit with a switching circuit and a controller that sends a test signal to the normally closed contact while de-energized, re-detects the signal if initial detection does not meet criteria, and assesses the re-detected signal as normal if it satisfies predetermined conditions, thereby reducing false assessments of abnormality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a normally closed contact is monitored using the state of a signal sent while the load is de-energized, then the monitoring process is simple, but temporary or recoverable factors occurring in the normally closed contact during monitoring are disadvantageously assessed as an abnormality
Solution Approach 1:
The controller performs a preliminary detection of the normally closed contact state before final assessment. When the first detection result does not satisfy the predetermined criteria, the controller conducts a second detection to confirm whether the abnormality is real or temporary, thereby avoiding false assessments due to transient factors
Solution Approach 2:
The monitoring system uses feedback by comparing the first detection result with a second detection result. When the first detection indicates abnormality but the second detection shows normal state, the system feedbacks that this is a temporary factor rather than a true abnormality, improving assessment accuracy
2Speed
If a test signal is sent to the normally closed contact and the detection result is immediately assessed, then the monitoring response is fast, but false abnormalities are assessed due to temporary factors such as vibrations or foreign particle intrusion
Solution Approach 1:
The system performs a preliminary detection followed by a confirmatory detection before final assessment. This two-stage approach maintains relatively fast response while improving precision by filtering out temporary interference factors through sequential verification
Solution Approach 2:
Instead of a single detection, the system performs an excessive action by conducting a second detection when the first is uncertain. This partial redundancy in detection actions ensures higher measurement precision by confirming results before final assessment
Data Source
Figure 1A
Figure 1B~1C
Figure 2A
AI summary
The reliability of testing a normally closed contact in a relay unit may involve the following. While the load is de-energized, sending a test signal to a normally closed contact (bl, b2) and detecting the state of the returning test signal sent. Resending a test signal when a detection result does not satisfy a predetermined criterion, and re-detecting the state of the returning test signal resent. The state of the returning test signal resent may be assessed as normal when the re-detection result satisfies the predetermined criterion.