Programmable Solid-State Relay Timing Control
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Solution Overview
Problem
Existing time delay relays in railway systems, based on resistor-capacitor (RC) circuits, face challenges with inaccurate and unpredictable timing due to exponential current discharge, requiring trial-and-error adjustments and being susceptible to temperature and aging effects, while electromechanical relays suffer from high contact resistance and mechanical wear.
Innovation Solution
A programmable solid-state relay with a microcontroller, countdown timer, and solid-state switching circuits, which allows for precise time delay programming and fault monitoring, replacing electromechanical relays with enhanced reliability and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If RC circuit timing is used, then the relay structure is simple, but the timing accuracy is poor and unpredictable
Solution Approach 1:
The patent replaces the RC circuit timing mechanism with a microcontroller-based digital timing system. The microcontroller uses a crystal oscillator to generate precise clock signals and implements timing through software countdown, eliminating the exponential discharge characteristics of RC circuits and providing linear, predictable, and accurate time delays.
Solution Approach 2:
The patent changes the timing parameter control from analog component values (R and C) to digital programmable values. The time delay is determined by a programmable counter loaded with a preset value, allowing precise control of timing parameters through software rather than being constrained by component tolerances and temperature effects.
2Device complexity
If RC circuit timing is used, then the device is simple, but the reliability is poor due to temperature and aging effects
Solution Approach 1:
The patent substitutes the temperature-sensitive RC circuit with a microcontroller system that uses a crystal oscillator for timebase generation. The crystal oscillator provides stable frequency output unaffected by temperature and aging, and the digital countdown implementation ensures consistent timing behavior over the device lifetime.
Solution Approach 2:
The microcontroller system includes built-in timing functionality with interrupt-driven operation, automatically managing the countdown and switching operations without requiring external adjustment or calibration. The system self-regulates timing accuracy through its internal clock mechanism, eliminating the need for manual potentiometer adjustments.
3Reliability
If electromechanical relays are used, then the switching function is achieved, but mechanical wear and contact resistance occur
Solution Approach 1:
The patent replaces electromechanical relay contacts with solid-state switching components controlled by the microcontroller. Transistors or solid-state relays are used to perform the switching function, eliminating mechanical contact wear, contact resistance, and associated reliability issues while extending the operational lifespan of the switching mechanism.
Data Source
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AI summary
A programmable solid state relay comprising: a relay base; an adaptor circuit; a configuration circuit; a trigger input; a voltage monitoring circuit monitoring the trigger input; a countdown timer; a microcontroller; and at least one switching circuits with first and second switching contacts, wherein: when the voltage of the trigger input exceeds a selectable trigger input threshold voltage, the countdown timer is loaded with a predetermined time value., the countdown timer is started and the at least one switching circuits are set to individually predetermined first states; and when the countdown timer has completed its countdown the at least one switching circuits are set to the complements of the first states. The relay performs self-checking of the switches and forces the switches to an open state upon detection of errors.