Communication Line Isolator Voltage Division and Chassis Pressure Management
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Solution Overview
Problem
Existing communication line isolators, particularly isolation-type LAN SPDs, face challenges in withstanding higher voltage surges without damaging connected communication devices and in preventing chassis bursting due to increased internal pressure from abnormal currents, especially when designed to handle voltages up to 13 kV and beyond.
Innovation Solution
The solution involves configuring the communication line isolator with an isolation transformer that connects parasitic capacitance and inner capacitance in series to divide abnormal voltages safely, and incorporating a pressure release mechanism in the chassis made of synthetic resin to prevent bursting during high-pressure events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the isolation transformer is designed to withstand higher voltage surges (e.g., 13 kV), then the protection capability against abnormal voltage is improved, but the internal pressure increases causing the chassis to burst
Solution Approach 1:
The patent applies this principle by using a synthetic resin chassis that is inherently more resistant to pressure buildup compared to traditional metal enclosures. The synthetic resin material provides flexibility and pressure distribution properties that prevent bursting while maintaining structural integrity during high-voltage surge events.
Solution Approach 2:
The patent changes the material parameter of the chassis from metal to synthetic resin, which fundamentally alters the pressure resistance characteristics. This material parameter change allows the chassis to withstand the internal pressure generated during 13 kV voltage surge events without bursting, while still providing adequate mechanical protection.
2Reliability
If the parasitic capacitance is increased to divide abnormal voltage more effectively, then the voltage division ratio is improved, but the communication signal quality deteriorates
Solution Approach 1:
The patent optimizes the parasitic capacitance value to a specific range that balances voltage division effectiveness with signal quality preservation. By carefully selecting and controlling the capacitance parameter, the system achieves adequate abnormal voltage division while minimizing interference with normal communication signals.
Solution Approach 2:
The patent applies different quality requirements to different functional aspects: the parasitic capacitance is designed to provide strong voltage division capability during abnormal conditions, while simultaneously maintaining low enough impedance to preserve signal quality during normal operation. This local optimization of electrical characteristics resolves the contradiction.
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 ensures that the communication devices are protected from excessive voltage without being damaged, and the chassis is prevented from bursting, even when subjected to high withstand voltages, maintaining the isolator's integrity and safety.
Implementation Method 1
an isolation transformer having a parasitic capacitance between a primary winding and a secondary winding. Therefore, even if the primary side corresponding to the power wire side or the communication wire side and the secondary side corresponding to the power device side or communication device side are isolated using an isolation transformer, part of an abnormal current such as a lightning surge which enters from the primary winding side of the isolation transformer passes to the secondary winding side of the isolation transformer by capacitive coupling by the parasitic capacitance.
Implementation Method 2
it is desirable to basically set an electrostatic shield between the primary winding side and the secondary winding side of an isolation transformer and fasten this electrostatic shield to the ground. By this means, it is possible to suppress an abnormal current flowed from the primary winding side to the secondary winding side
Data Source
Figure 1A
Figure 1B
Figure 2A~2B
AI summary
An isolator 10 is formed with an isolation transformer 13 that blocks an abnormal voltage entering from a communication line 30 and protects a protection target device 40. A pulse transformer 43 in the device 40 includes a primary winding 43a connected to a secondary winding 13b of the transformer 13 and a secondary winding 43b connected to an inner circuit. A medium tap of the primary winding 43a is grounded through an inner capacitance Ci of the device 40. A parasitic capacitance Cs between the primary winding 13a and the secondary winding 13b of the transformer 13 and the inner capacitance Ci are connected in series, an abnormal voltage is divided by the capacitance Cs and the capacitance Ci, and a capacitance value of the capacitance Cs is set such that the divided voltage of the capacitance Ci is equal to or below a predetermined value.