Current Transformer Docking Module for Overvoltage Protection
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Solution Overview
Problem
Current transformer protective circuits face challenges with high inertness, large size, high costs, and operational safety issues due to delayed response times and difficulty in accommodating devices within the secondary terminal box, especially when dealing with high secondary voltages in open-circuit conditions.
Innovation Solution
A docking module with a semiconductor-based protective circuit that can be mechanically fastened to the current transformer, featuring a control unit and switch unit for rapid response, low volume, and lower costs, which includes a semiconductor switch for quick short-circuiting when secondary voltage exceeds a threshold, and a limiting unit for overvoltage protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thermal overload relay is used for protective circuit, then the circuit can provide overvoltage protection, but the response time is delayed and the device size is large
Solution Approach 1:
The patent replaces the mechanical thermal overload relay with an electronic protective circuit comprising a semiconductor switch (such as triac or thyristor) controlled by an electronic control unit. This substitution eliminates the thermal inertia of mechanical relays, enabling rapid response to overvoltage conditions while maintaining protection functionality. The electronic circuit can detect and respond to voltage threshold exceedances almost instantaneously, resolving the contradiction between reliability and response time.
Solution Approach 2:
The patent changes the operating parameters of the protective circuit by using semiconductor devices with可控 switching characteristics. The semiconductor switch can be triggered at precise voltage thresholds and switched off rapidly when the threshold is no longer exceeded, providing both fast response and reliable protection. This parameter-based control replaces the thermal-mechanical operation, achieving quick response times without sacrificing protection reliability.
2Reliability
If a circuit breaker is used for protective circuit, then the circuit can provide overvoltage protection, but the device volume is large and accommodation in secondary terminal box is difficult
Solution Approach 1:
The patent extracts the essential protective function from the bulky circuit breaker and implements it through a compact electronic circuit. By separating the protection function from the heavy mechanical switching mechanism, the patent achieves the same overvoltage protection capability in a much smaller form factor that can be accommodated within the secondary terminal box of the current transformer.
Solution Approach 2:
The patent replaces the mechanical circuit breaker with an electronic protective circuit using semiconductor switches. This substitution dramatically reduces the device volume while maintaining the overvoltage protection function. The electronic components occupy minimal space compared to mechanical breakers, enabling integration into compact current transformer designs.
3Reliability
If a relay is used for protective circuit, then the circuit can provide overvoltage protection, but the production costs are high
Solution Approach 1:
The patent employs inexpensive semiconductor components (triacs, thyristors, resistors, capacitors) to build the protective circuit, replacing expensive mechanical relays and circuit breakers. These electronic components are mass-producible and cost-effective, significantly reducing the production cost while maintaining reliable overvoltage protection functionality throughout the device's operational life.
4Adaptability or versatility
If a protective circuit with mechanical fastening is used, then the docking module can be retrofitted to existing current transformers, but the response time may be delayed
Solution Approach 1:
The patent divides the protective circuit into a modular docking module that can be separately attached to existing current transformers. This segmentation allows the electronic protective circuit to be retrofitted without replacing the entire current transformer, maintaining adaptability while ensuring rapid response through the use of semiconductor-based protection electronics in the modular unit.
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 a compact, cost-effective, and safe protective circuit with rapid response times, ensuring operational safety and preventing secondary voltage exceeding thresholds, while being easily retrofittable and compatible with existing current transformers.
Implementation Method 1
The switch unit (18) is adapted to short-circuit the protective circuit input (12.1) in response to the control signal supplied from the control unit (16). The protective circuit comprises a semiconductor switch for quick short-circuiting when secondary voltage exceeds a threshold.
Implementation Method 2
The control unit (16) is adapted to supply a control signal to the switch unit (18) in response to the secondary voltage (Us) exceeding a secondary voltage threshold. The control unit may comprise a comparator unit which is adapted to provide the control signal to the switch unit if an input voltage of the comparator exceeds a threshold value.
Implementation Method 3
The protective circuit may comprise a limiting unit connected to the input of the protective circuit, for overvoltage protection. The limiting unit may comprise a voltage-dependent resistor.
Data Source
AI summary
The present disclosure relates to a docking module for a current transformer comprising:an electronic circuit andat least one electric connecting element for electrically coupling the circuit to the current transformer and for docking the docking module onto the current transformer.