DC Circuit Switch Protective Circuit for Overload Isolation
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Solution Overview
Problem
Existing DC power switch technologies are prone to damage from temporary overloads and input surges, particularly when distributing power to multiple devices, and lack effective isolation of faults to prevent damage to other loads.
Innovation Solution
A protective circuit with a voltage sensor and constant current source is used to safely enable power to a load by measuring voltage and current, determining if the switch can be safely actuated without exceeding the power supply capacity, and tripping the switch if overload conditions are detected.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a DC power switch uses a semiconductor element to distribute power to multiple devices, then the power distribution capability is improved, but the switch becomes vulnerable to damage from temporary overloads and input surges
Solution Approach 1:
The control circuit performs preliminary measurements before closing the switch by applying a test current through the constant current source and measuring the resulting voltage. This preliminary action detects potential overload conditions before full power is applied, preventing damage to the semiconductor switch while maintaining its ability to distribute power to multiple devices.
Solution Approach 2:
The control circuit continuously monitors voltage across the switch and current through the switch, using this feedback to detect overload conditions and trip the switch when necessary. This feedback mechanism protects the semiconductor switch from damage while enabling safe power distribution to multiple loads.
2Productivity
If the switch is turned on to supply power to the load, then the power delivery function is improved, but existing faults cause a trip of the breaker with transient effect on the power source
Solution Approach 1:
The control circuit performs preliminary measurements by applying a test current and measuring voltage before closing the switch. This preliminary action detects faults such as short circuits or overload conditions before full power is applied, allowing the system to identify and isolate faulty loads without causing transient effects on the power source.
Solution Approach 2:
The control circuit applies a counter-action by measuring voltage and current characteristics before switch closure to prevent harmful fault conditions from occurring. This preliminary anti-action detects potential faults and prevents them from causing damage, enabling safe power delivery while maintaining reliability.
3Reliability
If the switch remains off to prevent fault conditions, then the protection function is improved, but no equipment connected to the output and voltage may be inadvertently applied to an exposed power terminal
Solution Approach 1:
The control circuit performs preliminary measurements by applying a test current through the constant current source and measuring the resulting voltage before closing the switch. This preliminary action verifies that a valid load is connected and prevents voltage from being applied to exposed terminals, eliminating the hazard while maintaining protection functions.
Solution Approach 2:
The control circuit uses the load itself to provide verification of proper connection. By measuring voltage across the switch during the preliminary measurement phase, the system determines whether a valid load is present, allowing safe energization only when appropriate and preventing hazards from exposed terminals.
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 prevents damage from overloads and faults by ensuring the switch operates within safe current limits, isolating faults, and maintaining switch status for power restoration, thus protecting the power supply and connected loads.
Implementation Method 1
a voltage sensor and a constant current source connected to the output terminal of an electrically controllable switch
Implementation Method 2
controlling the constant current source to apply a predetermined current to the load connection for a predetermined period of time
Data Source
AI summary
An apparatus, system and method of controlling the supply of DC current from a power source to an electrical load provides for a protective circuit that senses the characteristics of the connected load prior to permitting the enablement of a switch connecting the supply and the load. A voltage arising from applying a constant current to the load during a time period is compared with a predetermined threshold determined by the intended capacity of the switch so that, when closed, the current through the switch is compatible with the switch. The protective circuit may be used in conjunction with semiconductor switches, electromechanical contactors or relays. A plurality of such devices may be incorporated in an enclosure and controlled by logic so as to manage the supply of power from a power source to a plurality of electrical loads having differing power requirements.