Thermal-Magnetic Tripping Device for Polyphase Circuit Breakers
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Solution Overview
Problem
Current thermal-magnetic trip devices for polyphase circuit breakers cannot distinguish between tripping causes due to current overloads and short circuits, requiring manual inspection to determine the origin of the anomaly, and existing solutions are complex and not easily adaptable.
Innovation Solution
A thermomagnetic trip device with multiple thermal and magnetic actuators, an intermediate transmission device, and indicators to mechanically differentiate between overload and short-circuit tripping causes, using pivoting transmission bars and elastic members to signal the cause of tripping through visible indicators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thermal-magnetic trip device is used to monitor phase currents and trip the circuit breaker, then protection against overcurrents and short circuits is provided, but the cause of tripping (overload vs. short circuit) cannot be distinguished
Solution Approach 1:
The trip device is segmented into separate thermal actuators for each phase that respond to overloads and magnetic actuators for each phase that respond to short circuits. Each actuator type is mechanically independent and drives the trip mechanism through distinct paths, allowing the cause of tripping to be identified by which actuator triggered the trip.
Solution Approach 2:
The patent uses visual indicators (such as colored flags or positions) to show the cause of tripping. The first indicator shows a first position when a thermal actuator trips the breaker (indicating overload), and a second position when a magnetic actuator trips the breaker (indicating short circuit), providing immediate visual information about the tripping cause.
2Loss of information
If existing solutions are used to mechanically display the cause of tripping, then the tripping cause can be identified, but the mechanism becomes complex and bulky with many constituents
Solution Approach 1:
The patent merges the indication function into the existing trip mechanism by using the positions of the thermal and magnetic actuators themselves as the indication system. The actuators' relative positions and their connection to the trip mechanism serve dual purposes: triggering the trip and indicating the cause, eliminating the need for separate complex indication mechanisms.
Solution Approach 2:
The thermal and magnetic actuators serve multiple functions: they detect the respective fault conditions (overload or short circuit), mechanically drive the trip mechanism to open the breaker, and simultaneously provide visual indication of the fault type through their positions and connections. This multi-functionality reduces overall device complexity.
3Loss of information
If existing solutions are used to mechanically display the cause of tripping, then the tripping cause can be identified, but the mechanism is not easily adaptable to certain circuit breakers
Solution Approach 1:
The indication mechanism is designed to be dynamic and adaptable to different circuit breaker types. The thermal and magnetic actuators are configured to work with various breaker mechanisms, and the indication system adapts its display based on which actuator triggers the trip, making the solution versatile across different circuit breaker designs without requiring fixed complex mechanisms.
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 clear mechanical indication of tripping causes, simplifying post-trip inspections and improving adaptability to various circuit breakers by distinguishing between current overloads and short circuits without increasing complexity.
Implementation Method 1
several thermal actuators, each of which is designed to react to a current overload in one of the phases by generating a mechanical trip command
Implementation Method 2
thermal actuators, each of which is designed to react to a current overload
Implementation Method 3
several magnetic actuators, each of which is designed to react to a short-circuit in one of the phases by generating a mechanical release control
Data Source
Figure 1~2
Figure 3~4
Figure 5~7
AI summary
The device has a set of thermal actuators (40), where each actuator is designed to react to a current overload in one of a set of phases by generating mechanical tripping commands (P1, P2). A transmission bar (31) is fitted on a support shaft, and a ratchet (30) is fitted on the support shaft. Another transmission bar (32) drives the ratchet from its latched position to its released position so as to change a state of an indicator. The former transmission bar and the latter transmission bar are disconnected from one another while pivoting around a pivoting axis (Y2, Y'2).