Electronic Load Protection Using Voltage-Difference Short-Circuit Detection
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Solution Overview
Problem
Existing protective devices for electrical loads, such as melt fuses and PTC resistors, struggle to quickly and efficiently distinguish between short circuits and inrush currents, leading to potential system failures and increased downtime.
Innovation Solution
A method and device that utilize a temporal short test sequence to differentiate between uncritical and critical current curves by detecting output voltage differences after a short switching-on and switching-off process, allowing for rapid identification of short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If melt fuses or PTC resistors are used for overcurrent protection, then the system can protect against short circuits and overloads, but the response time is slow (milliseconds to seconds) and physical replacement or manual intervention is required
Solution Approach 1:
The patent replaces mechanical/thermal protective devices (melt fuses, PTC resistors) with an electronic control system that uses microcontrollers, voltage dividers, and electronic switching components. This substitution enables rapid detection and response to overcurrent conditions through electronic signal processing rather than thermal accumulation, reducing response time from milliseconds/seconds to microseconds while eliminating the need for physical replacement.
Solution Approach 2:
The electronic protection system automatically detects overcurrent conditions, determines the type of load (capacitive, inductive, or ohmic), and switches off the appropriate circuit breaker without requiring manual intervention. The system self-diagnoses the fault condition and executes the protection sequence autonomously, eliminating the need for physical replacement of fuses or manual resetting of protective devices.
2Reliability
If conservative fuse nominal current is selected to ensure protection, then the system can prevent damage, but the fuse may be triggered by inrush currents causing unnecessary downtime
Solution Approach 1:
The patent performs preliminary identification of the load type (capacitive, inductive, or ohmic) before the overcurrent protection is activated. By pre-characterizing the load's electrical properties during normal operation or initial power-up, the system can distinguish between legitimate inrush currents associated with specific load types and actual fault conditions. This preliminary classification enables the protection algorithm to adjust its response criteria accordingly, preventing false tripping while maintaining protection accuracy.
Solution Approach 2:
The system dynamically adjusts protection parameters based on the identified load type. Different load types (capacitive, inductive, ohmic) have different characteristic current profiles and time constants. The electronic control system modifies the overcurrent detection thresholds and response timing parameters according to the specific load characteristics, allowing higher tolerances for expected inrush currents while maintaining sensitivity to actual faults. This parameter adaptation eliminates unnecessary fuse tripping while preserving protection effectiveness.
3Device complexity
If the system uses heating effect-based protection (melt fuses, PTC resistors), then the device structure is simple, but it cannot control inrush currents, overvoltage, reverse current and reverse voltage protection required in modern electronic systems
Solution Approach 1:
The patent implements a universal electronic protection platform that can provide multiple protection functions (overcurrent, inrush current, overvoltage, reverse current, reverse voltage) through a single integrated control system. The microcontroller-based architecture with voltage division networks and electronic switching components can detect and respond to various fault conditions using the same hardware infrastructure, eliminating the need for separate protective devices for each function while expanding protection capabilities beyond what simple thermal devices can offer.
Data Source
AI summary
A method of protecting an electrical load (L) connectable to an electrical power source (B) via a switch (S), in the event of short circuit of the load (L), comprises the following steps of: connecting the load (L) to the electrical power source (B) by a first switching-on of the switch (S), detecting an output current (IA) of the switch (S), switching off the switch (S), when the output current (IA) exceeds an overcurrent threshold (IA_S) and/or a predetermined period of time (TD) has elapsed since the first switching-on of the switch (S), detecting an output voltage (UA) of the switch (S), determining an output voltage difference (AUA) of the output voltage (UA) between a predetermined first point in time (T1) and a predetermined second point in time (T2) after the first point in time (T1), a second switching-on of the switch (S), when the output voltage difference (AUA) is negative and has an absolute value that is less than an upper output voltage difference threshold (AUA_S1), and/or the switch (S) was switched off after the predetermined period of time (TD) and the detected output current (IA) has not exceeded the overcurrent threshold (IA_S) since the first switching-on at least until the switching-off.