Differential Protection Device Fire Break RC Circuit
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Solution Overview
Problem
Existing differential protection devices for electrical installations, particularly those classified as type B+, require complex and costly constructions with two independent circuits to achieve the necessary frequency template for fire detection, with the firebreak function being inoperative without power supply.
Innovation Solution
Incorporating a series RC circuit, comprising a resistor and capacitor, connected in parallel with the secondary winding of a toroid, to adapt the bandwidth and provide a firebreak function independent of the power supply, with specific resistor values optimizing impedance for high frequencies and capacitance values setting the trigger threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two independent circuits are implemented to achieve type B+ frequency response, then fire detection capability is improved, but device complexity and cost increase
Solution Approach 1:
The patent combines the fire detection function with the existing differential protection circuit by adding a passive RC network to the secondary winding. This merges two previously separate functions (differential protection and fire detection) into a single integrated device, eliminating the need for two independent circuits while maintaining both capabilities.
Solution Approach 2:
The differential protection device is enhanced to perform multiple functions: standard differential protection for personnel safety and fire detection through the RC network. The single device now serves universal purposes, replacing the need for separate fire detection equipment and reducing overall system complexity.
2Reliability
If active electronic assembly is implemented for fire detection, then frequency response is improved, but power supply dependency increases
Solution Approach 1:
The fire detection function is achieved through a passive RC network that operates autonomously without requiring external power supply. The circuit uses the induced voltage from the secondary winding itself to drive the detection mechanism, making the system self-sufficient and eliminating power supply dependency for fire detection operations.
Solution Approach 2:
The patent replaces active electronic circuits with a passive RC network that uses fundamental electrical properties (resistance and capacitance) to achieve frequency-selective fire detection. This substitution eliminates the need for powered electronic components while maintaining detection capability through passive electrical characteristics.
3Reliability
If series RC circuit is added to secondary winding, then firebreak function operates without power supply, but device structure becomes more complex
Solution Approach 1:
The patent modifies the electrical parameters of the existing differential protection device by introducing an RC network with specific resistance and capacitance values. This changes the frequency response characteristics of the secondary winding, enabling fire detection capability while using simple passive components rather than complex active circuits.
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
This solution simplifies the device structure, reduces costs, and ensures the firebreak function operates without power supply, offering improved sensitivity and reliability in detecting fault currents conducive to fire outbreaks.
Implementation Method 1
the conductors of the circuit to be protected, or the conductors of the supply line to this circuit, pass through a ferromagnetic core of a transformer. The aforementioned conductors form the primary winding of this core, which has one or more secondary windings. The core acts as a magnetic flux concentrator.
Implementation Method 2
in the event of a leakage, resulting in an imbalance between the input and output currents in the conductors of the lines to be protected, the flux created in the core by this imbalance in the primary winding induces a voltage in the secondary winding.
Data Source
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AI summary
The present invention relates to a differential protection device allowing the detection of a leakage current or default current in an electrical installation supplied by at least one phase conductor forming the primary winding of a toroidal core (T), the signal induced at the secondary winding (S) of said toroidal core (T) when a differential default appears at the primary winding being used in at least one suitable signal processing stage (ETS) of said device, in order to control a relay (MC) of the device if a predefined threshold value is exceeded, said stage(s) (ETS) being directly or indirectly connected to the terminals of the secondary winding (S) under consideration.The device is characterized in that it comprises at least one circuit RC made up of a first resistance (R) having a defined value and a first capacitance (C) having a defined value, which are arranged in series, said circuit RC being connected to the terminals of the secondary winding (S) and mounted in parallel and upstream of the signal processing stage(s) (ETS).