Thermostat having over current management
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Solution Overview
Problem
Conventional thermostats lack effective over current protection for control input/output wiring to HVAC systems, leading to potential damage and nuisance trips due to excessive current, with existing solutions failing to manage short-term overcurrent events and fault annunciation.
Innovation Solution
A thermostat with integrated over current management, featuring a processor, over current detector, timer, and counter that activates and deactivates switches based on detected overcurrent conditions, manages retries, and communicates service requirements through a network connection to prevent damage and unnecessary trips.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional thermostats depend on external circuit breakers for over current protection, then the thermostat structure remains simple, but the protection is insufficient and causes nuisance trips with long time constants allowing wire heating
Solution Approach 1:
The patent combines the over current detection and management functions directly into the thermostat device, merging previously separate protection functions into a unified system. This integration allows the thermostat to monitor and respond to over current conditions internally, eliminating dependence on external circuit breakers and their associated delays.
Solution Approach 2:
The patent implements preliminary over current detection and response mechanisms within the thermostat that act before damage occurs. The system detects over current conditions and can respond immediately by controlling HVAC system operation, preventing the cumulative heating effects that occur with conventional circuit breakers that have long time constants.
2Object-affected harmful factors
If conventional circuit breakers trip at twice the rated current after a 1 second time constant, then the protection mechanism is simple, but heating of wires, contacts and traces occurs before tripping
Solution Approach 1:
The patent applies preliminary anti-action by detecting over current conditions and responding before significant heating occurs. The system uses detection circuits to identify excessive current flow and immediately adjusts HVAC operation to prevent the harmful heating effect from developing, acting in advance rather than reacting after damage begins.
Solution Approach 2:
The thermostat implements preliminary protection by continuously monitoring current conditions and responding to over current states before they cause thermal damage. The system's internal detection and response mechanism acts preemptively to prevent wire, contact, and trace heating that would occur with conventional delayed tripping.
3Reliability
If hardware components alone are used for over current detection, then the detection mechanism is simple, but connectivity is broken without management of short period overcurrent events and fault annunciation
Solution Approach 1:
The patent implements multi-functional control circuitry that performs over current detection, short period event management, fault annunciation, and HVAC control coordination. This universal control system handles multiple protection and management functions that would otherwise require separate dedicated components, providing comprehensive over current management while maintaining reasonable device complexity.
Solution Approach 2:
The patent employs feedback mechanisms where the control circuitry continuously monitors over current conditions and adjusts system operation accordingly. The feedback loop detects over current events, determines their duration and severity, and coordinates appropriate responses including fault annunciation and connectivity management, creating a closed-loop protection system.
4Object-affected harmful factors
If external circuit breakers are not provided in the HVAC system, then the system installation is simpler, but excessive current can be output causing dangerous conditions in occupied spaces
Solution Approach 1:
The patent enables the thermostat to provide its own over current protection capabilities without requiring external circuit breakers. The self-service protection system includes internal detection circuits and control logic that monitor and respond to excessive current conditions, allowing the HVAC system to protect itself without additional external protection devices.
Solution Approach 2:
The patent merges the over current protection function into the thermostat unit itself, combining previously separate protection functions with the control device. This integration eliminates the need for external circuit breakers while maintaining comprehensive protection against excessive current dangers in occupied spaces.
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 effectively inhibits damage to the thermostat and surrounding components, avoids unnecessary trips of power distribution circuits, and identifies service issues with stuck relays or switches, ensuring safe and reliable operation of HVAC systems.
Implementation Method 1
The over current detector compares the power input signal when present on the power input terminal to a pre-determined current level and generates an over-current condition on the over current detector output when a current of the power input signal exceeds the pre-determined current level
Data Source
AI summary
An environmental control device (100, 200), such as a thermostat, is disclosed. The environmental control device (100, 200) has one or more terminals (104, 104a-104i) for connecting to an HVAC system (14) and performs over current management of the terminal (104, 104a-104i) when connected to the HVAC system (14).