Surge Protective Circuit Component Sharing for Size Reduction
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Solution Overview
Problem
Conventional surge protective devices (SPDs) are prone to failure when subjected to repeated overvoltages, leading to a higher likelihood of malfunction compared to insulated transformers, and duplicating components to mitigate this issue increases the number of components and makes it difficult to reduce size.
Innovation Solution
A surge protective circuit configuration that includes a first and second constant-voltage device (varistor) and discharge device (gas arrestor) connected in series between ground and non-ground terminals, with midpoints connecting the components to allow for efficient discharge of surge currents, reducing the number of components required while ensuring reliable protection against lightning surges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If surge protective devices are duplicated to improve reliability, then protection reliability is improved, but the number of components increases and device size increases
Solution Approach 1:
The patent combines two surge protective circuits into a single integrated device where the first and second constant-voltage devices and discharge devices share common connection points and ground terminals. This merging approach achieves the reliability of duplicated protection while reducing the overall component count and device size compared to completely separate duplicated circuits.
Solution Approach 2:
The ground terminals and connection points serve multiple functions - they are shared by both surge protective circuits, allowing the same physical components to provide protection paths for both circuits. This multi-functionality reduces the total number of components needed while maintaining dual-circuit protection capability.
2Reliability
If surge protective devices are duplicated to improve reliability, then protection reliability is improved, but device size increases
Solution Approach 1:
The patent merges two surge protective circuits into a compact integrated structure where components are shared and connection points are common. This reduces the physical footprint compared to completely separate duplicated devices while maintaining the reliability benefits of having dual protection circuits.
Solution Approach 2:
By making ground terminals and connection points serve both circuits simultaneously, the device achieves dual-circuit protection capability in a single compact housing rather than requiring two separate devices, thereby reducing overall device size.
3Reliability
If insulated transformer is used to protect from lightening surge, then protection reliability is improved, but installation space is large
Solution Approach 1:
The patent replaces the mechanical/physical insulation approach of traditional insulated transformers with electronic surge protective circuits using varistors and gas arrestors. This substitution enables reliable surge protection in a much more compact form factor suitable for modern electronic equipment.
Solution Approach 2:
The invention changes the protective mechanism from electromagnetic isolation (transformer) to voltage-dependent discharge (varistor/gas arrestor), allowing for compact integration while maintaining protection effectiveness. The surge protective circuits can be mounted directly on equipment without requiring the large physical separation and insulation structure of transformers.
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
This configuration effectively reduces the number of components needed while ensuring reliable protection against lightning surges, even in the event of component failures, by allowing surge currents to be discharged through alternate paths, thus maintaining protection and reducing the overall size of the protective system.
Implementation Method 1
a first constant-voltage device (for example, a first varistor 31 to be described later) and a first discharge device (for example, a first gas arrestor 33 to be described later) connected in series between a first ground terminal (for example, a first ground terminal 35 to be described later) and a non-ground-side terminal
Implementation Method 2
a first discharge device (for example, a first gas arrestor 33 to be described later) connected in series between a first ground terminal (for example, a first ground terminal 35 to be described later) and a non-ground-side terminal
Data Source
AI summary
A surge protective circuit is connected between a single-phase AC power source and an apparatus that operates with electric power supplied from the AC power source to suppress an overvoltage applied from the AC power source to the apparatus. The surge protective circuit includes: a first constant-voltage device and a first discharge device connected in series between a first ground terminal and a non-ground-side terminal of the AC power source; and a second constant-voltage device and a second discharge device connected in series between a second ground terminal and a ground-side terminal of the AC power source. A midpoint between the first constant-voltage device and the first discharge device and a midpoint between the second constant-voltage device and the second discharge device are connected.