Programmable Logic Control Device with Thermistor Stabilization
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Solution Overview
Problem
Existing programmable logic control devices for electrical circuits are prone to spurious tripping due to temperature fluctuations, transient spikes, and radiation exposure, leading to unnecessary power loss and erratic safety functions, particularly in harsh environments like nuclear reactors.
Innovation Solution
The programmable logic control device incorporates thermistors for temperature stabilization, enhanced time constants to ride out voltage spikes, and radiation-resistant ceramic packaging for integrated circuits, reducing nuisance tripping and ensuring reliability in harsh conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional programmable logic control devices are used without temperature stabilization, then the device structure remains simple, but the device is susceptible to temperature fluctuations causing spurious tripping
Solution Approach 1:
A thermistor is introduced as an intermediary component between the power supply and the programmable logic control circuitry. The thermistor absorbs temperature-related variations and stabilizes the voltage supplied to the logic device, preventing spurious tripping caused by temperature fluctuations while maintaining relatively simple overall device structure.
Solution Approach 2:
The patent changes the electrical parameters (voltage stability) by introducing a thermistor with specific temperature-coefficient characteristics. This thermistor compensates for temperature-induced parameter changes in the logic control device, maintaining reliable operation across temperature variations without requiring complex temperature sensing and control systems.
2Reliability
If the programmable logic control device has fast response time, then it can quickly detect faults, but it is more susceptible to transient spikes causing spurious tripping
Solution Approach 1:
The circuit incorporates beforehand cushioning elements (such as RC filtering networks and voltage clamping devices) that are positioned to absorb or attenuate transient voltage spikes before they reach the programmable logic control device. This cushioning protection allows the device to maintain fast response times for legitimate faults while being resilient to spurious transient spikes.
3Reliability
If standard packaging materials are used for integrated circuits, then manufacturing cost is low, but the device is susceptible to radiation damage in harsh environments
Solution Approach 1:
The patent specifies the use of ceramic packaging materials for the integrated circuits instead of conventional plastic or metal encapsulations. Ceramic materials provide superior resistance to radiation, temperature extremes, and chemical corrosion, making the device suitable for harsh environments such as nuclear reactor applications. While ceramic packaging increases manufacturing cost compared to standard materials, it significantly enhances reliability in radiation-prone environments.
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
The solution significantly reduces the likelihood of spurious tripping, maintaining consistent performance across temperature variations and withstanding transient spikes and radiation, making it suitable for harsh environments such as nuclear reactors.
Implementation Method 1
The present invention provides a thermister means for stabilizing the circuitry of the programmable logic control device such that the device is less susceptible to temperature fluctuations
Implementation Method 2
The present invention provides a programmable logic control device having an improved time constant for the purposes of riding out spurious voltage spikes
Data Source
AI summary
An improved programmable logic control device for monitoring the current of a circuit and for signalling a circuit control device, the programmable logic control device including electrical power circuitry for activating the circuit control device and electrical circuitry for monitoring the current in the electrical circuit, the electrical circuitry including: adjustable electrical signal input circuitry to monitor the electrical current in the circuit; adjustable pick-up circuitry for adjusting the level of the current monitored in the electrical circuit, the pick-up circuitry having a thermister means for improved stabilization; adjustable time circuitry to command the electrical power circuitry to activate the circuit control device when the electrical current in the electrical circuit reaches the selected level and time duration, the time circuitry having an increased time duration to minimize nuisance tripping; and a zener diode in reverse mode for controlling the level of voltage applied to the adjustable pick-up circuitry and time circuitry substantially without resistive burden, the zener diode in reverse mode passing a reference voltage which is less than an input voltage to the said device. The device is preferably packaged in material that is resistant to radiation, such as ceramic, and is well-suited for harsh environment applications.