Surge Protector Voltage Limiting Circuits
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Solution Overview
Problem
Existing surge protection devices for sensitive equipment are inadequate in addressing power surges, as they either fail to provide comprehensive protection or increase in size and cost without proportional benefit, limiting their effectiveness in preventing damage from power surges.
Innovation Solution
A surge protector design incorporating multiple voltage limiting circuits and inductors, with specific trigger voltages and residual voltage characteristics, coupled between line, neutral, and ground connections to manage power surges effectively, including metal oxide varistors and gas discharge tubes for enhanced protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional components are added to existing surge protection devices to provide additional protection, then the protection capability is improved, but the cost and device size increase
Solution Approach 1:
The surge protection device is divided into multiple independent voltage limiting circuits, each protecting specific line pairs (line-neutral, line-ground, neutral-ground). Each circuit operates autonomously with its own voltage limiting component, allowing targeted protection without requiring a monolithic complex structure. This segmentation enables comprehensive protection while maintaining modular simplicity.
Solution Approach 2:
Different voltage limiting circuits are assigned different trigger voltages and residual voltage characteristics according to their specific protection needs. The first voltage limiting circuit (line-neutral) has lower trigger voltage than the second (line-ground/neutral-ground), creating optimized local protection characteristics for each circuit rather than using uniform protection across all lines.
2Reliability
If multiple voltage limiting circuits with different trigger voltages are used, then the protection effectiveness is improved, but the device complexity increases
Solution Approach 1:
The protection system is segmented into five independent voltage limiting circuits (first through fifth), each with specific voltage limiting components (MOV or GDT) protecting different line combinations. This segmentation allows each circuit to be optimized independently while maintaining overall system simplicity through modular repetition of the same basic circuit topology.
Solution Approach 2:
The voltage limiting circuits utilize parameter changes in voltage-dependent components (MOV and GDT) to provide dynamic protection. These components have non-linear resistance characteristics that change dramatically at their trigger voltages, automatically adjusting their protection level based on the surge magnitude without requiring complex control circuitry.
3Reliability
If series inductance is added to limit current from power surges, then the current limiting capability is improved, but the device size and complexity increase
Solution Approach 1:
The voltage limiting circuits are merged with series inductors to create combined protection units. Each voltage limiting circuit (first through fifth) has an associated series inductor that works together with the voltage limiting component to provide both voltage clamping and current limiting functions in a single integrated circuit, reducing overall device complexity compared to separate protection stages.
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 provides improved protection against power surges by controlling voltage and current across various connections, ensuring that the voltage across sensitive loads remains below harmful levels, meeting or exceeding industry standards like UL 1449 3rd Edition, and offering advantages over capacitive designs with reduced leakage currents and additional powerline filtering.
Implementation Method 1
Each of the first, third and fifth voltage limiting circuits may include a metal oxide varistor
Implementation Method 2
The second voltage limiting circuit may include a first gas discharge tube
Implementation Method 3
the resistive device may include a positive temperature coefficient resistor
Implementation Method 4
limiting current from the power surge across the line and neutral connections through the first voltage limiting circuit using a series inductance coupled between the line connection and the first node
Data Source
Figure 1
Figure 2
AI summary
A system and method for providing surge protection. The system includes a surge protector (100) for protecting a load (104) coupled to a power source (102). The surge protector (100) includes an input having a first node, a second node, and a third node for respectively coupling to line, neutral, and ground connections of the power source (102), an output having a fourth node, a fifth node, and a sixth node for respectively coupling to line, neutral, and ground connections of the load (104), a first voltage limiting circuit (110) coupled between the fourth node and the fifth node, a first inductor (116) coupled between the first node and the fourth node, and a second voltage limiting circuit (106) coupled between the first node and the second node. The system and method provide protection for sensitive circuits against power surges on power lines.