Undervoltage Release Circuit for Voltage Circuit-Breaker Tripping
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Solution Overview
Problem
Existing undervoltage release circuits for tripping circuit breakers face challenges in balancing the magnetic force of solenoids and spring forces across varying temperatures, leading to inconsistent tripping and recharging performance, requiring complex mechanisms or large solenoids to meet specific voltage conditions.
Innovation Solution
An undervoltage release circuit incorporating a voltage determining device with a diode and resistors controlling a transistor switch in series with the solenoid, allowing for a command signal to manage the solenoid's operation based on measured control voltage, eliminating the need for force balance between the solenoid and spring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a solenoid is used to hold the spring in charged position against varying temperatures, then the magnetic force must be strong enough to overcome spring force at high temperatures, but this causes the solenoid to be oversized and the system to fail to trip at low temperatures
Solution Approach 1:
The patent introduces a voltage-detecting circuit as an intermediary between the control voltage and the solenoid. This circuit monitors the control voltage and controls the solenoid's activation state accordingly, eliminating the need for the solenoid to directly balance against spring force across temperature variations. The voltage-detecting circuit acts as a mediator that translates voltage conditions into appropriate solenoid control signals.
Solution Approach 2:
The patent replaces the mechanical force-balancing system (solenoid directly opposing spring force) with an electrical control system (voltage-detecting circuit controlling solenoid activation). This substitution eliminates the temperature-dependent force balance problem by using electrical voltage detection and control logic to determine when tripping should occur, rather than relying on mechanical force equilibrium that varies with temperature.
2Reliability
If a complex mechanical system is used to achieve force balance between solenoid and spring, then the tripping performance improves, but the device complexity and cost increase significantly
Solution Approach 1:
The patent replaces complex mechanical force-balance mechanisms with a simpler electrical control system. Instead of using mechanical components to balance and adjust forces between the solenoid and spring, the invention uses a voltage-detecting circuit that electronically monitors control voltage and controls solenoid activation. This electrical approach achieves consistent tripping performance without the complexity of mechanical adjustment mechanisms.
Solution Approach 2:
The patent changes the control parameter from mechanical force balance to electrical voltage detection. By monitoring the control voltage electrically and using it to control solenoid activation, the system achieves consistent tripping performance based on voltage thresholds rather than mechanical force equilibrium. This parameter change simplifies the system while maintaining or improving tripping reliability.
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
Simplifies the design by ensuring the solenoid's magnetic force is sufficient for charging at high voltage and tripping at low voltage, independent of temperature, using standard solenoids and reducing the complexity and cost of the mechanism.
Implementation Method 1
The solenoid acts against a spring and is connected to a trip-latch. As long as the control-voltage is high enough, the solenoid holds the spring in charged position.
Implementation Method 2
the voltage determining device comprising means for measuring the control-voltage and means for generating a signal according to the control voltage measured
Implementation Method 3
the voltage determining device comprises a diode in series with a first resistor and a second resistor and the switching element is made of a transistor
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
Undervoltage release circuit comprising a solenoid (3) and a spring, the solenoid (3) acting against the spring and being connected to a trip-latch which trips a circuit-breaker as soon as a control voltage drops under a voltage level, characterized in that it comprises a voltage determining device (1) and a switching element (2) controlled by a command signal, the switching element (2) being connected in series with the solenoid (3), the voltage determining device (1) comprising means for measuring the control-voltage and means for generating a signal (K) according to the control voltage measured, the signal (K) according to the control voltage measured constituting the command signal (K) so that the switching element (2) is closed when the control voltage measured is equal or higher than the voltage level and opened as soon as the control voltage is less than the voltage level.