Low-Inductance Mechanical Switch for Transient Overvoltage Protection

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Solution Overview

Problem

Existing circuit arrangements for protecting consumers in decentralized energy systems, such as those connected to wind turbines, are inadequate in addressing transient and temporary overvoltages, leading to component damage and maintenance delays, with insufficient response times and inadequate overvoltage protection, especially during system testing and operation outside conventional network tolerances.

Innovation Solution

A circuit arrangement featuring a fast-acting, mechanical low-inductance switch with independent energy storage for rapid tripping, combined with adjustable transient overvoltage protection and additional overvoltage protection on the load side, allowing for precise voltage monitoring and quick disconnection/reconnection within a narrow tolerance window, ensuring safe operation up to line-to-line voltage without impairing existing protection devices.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If conventional voltage measurement and evaluation methods are used with delay elements, then the system can operate with simpler circuitry, but the response time to voltage anomalies increases to several hundred milliseconds or seconds

Engineering Contradiction:
Improveresponse timeVSAvoidcircuit complexity
Core Design Contradiction:
SpeedVSDevice complexity

Solution Approach 1:

The voltage protection function is segmented into two independent parts: a fast-acting mechanical switch for immediate disconnection and an electronic control system for monitoring and coordination. This segmentation allows the mechanical switch to respond within milliseconds without being burdened by complex electronic processing, while the electronic system handles measurement and decision-making separately.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The mechanical switch is pre-positioned and ready to actuate immediately upon detection of dangerous voltage conditions. The independent energy storage system is pre-charged to provide instantaneous actuation energy, eliminating the need for complex real-time energy management during the switching event.

Inventive Principle:
Principle #10Preliminary action

2Adaptability or versatility

If the tolerance range for operating voltage is widened to accommodate decentralized energy systems, then more systems can be integrated, but component stress increases and protection becomes more difficult

Engineering Contradiction:
Improvegrid integration capabilityVSAvoidcomponent stress
Core Design Contradiction:
Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The protection system dynamically adapts to different voltage conditions by allowing extended tolerance ranges during normal operation while maintaining the capability for rapid disconnection when voltage parameters exceed safe thresholds. The mechanical switch is designed to handle a wide voltage range, and the electronic control system adjusts monitoring thresholds based on system conditions.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The system incorporates pre-positioned mechanical protection that activates before irreversible component damage can occur. The independent energy storage and fast-acting mechanical switch create a protective barrier that cushions components from voltage extremes, allowing the system to tolerate wider voltage variations without increasing component stress.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

3Reliability

If existing surge arresters are used for transient protection, then transient loads are protected, but the devices fail during temporary or permanent overvoltages due to design limitations

Engineering Contradiction:
Improveprotection reliabilityVSAvoidvoltage condition coverage
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The invention merges transient surge protection with temporary overvoltage protection into a unified system. The mechanical switch provides backup protection that activates when electronic control detects sustained overvoltage conditions, complementing rather than replacing traditional surge arresters. This combination ensures protection across the full spectrum of voltage anomalies.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The electronic control system acts as an intermediary between transient surge arresters and temporary overvoltage conditions. It monitors voltage continuously and coordinates the mechanical switch activation to provide seamless protection, allowing surge arresters to handle transient events while the mechanical system handles sustained overvoltages.

Inventive Principle:
Principle #24Intermediary (Mediator)

4Speed

If fast-acting mechanical switches with independent energy storage are used, then disconnection occurs within milliseconds, but the switch requires significant actuation energy

Engineering Contradiction:
Improveswitching speedVSAvoidactuation energy
Core Design Contradiction:
SpeedVSUse of energy by moving object

Solution Approach 1:

The mechanical switch's actuation energy is stored independently in advance in a dedicated energy storage system. This pre-stored energy is released instantly when disconnection is required, enabling millisecond-level response without drawing power from the protected circuit during the switching event.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The energy storage function is segmented from the main protected circuit and dedicated solely to switch actuation. This independent energy storage system ensures that the switching operation has sufficient energy without burdening the circuit being protected, maintaining both speed and energy efficiency.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentEP3437169B1Circuit arrangement for protecting loads connected to a multi-phase network, having undervoltage and overvoltage switch-off function
Publication Date: 2023.07.12 DEHN SOHNE GMBH CO KG
  • EP3437169B1 patent drawingFigure 1
  • EP3437169B1 patent drawingFigure 2
  • EP3437169B1 patent drawingFigure 3

AI summary

The invention relates to a circuit arrangement for protecting loads (7) connected to a multi-phase network (L1; L2; L3), having an undervoltage and overvoltage switch-off function, transient overvoltage protection, and network reconnection, wherein each load (7) can be connected to the network by means of a multi-pole switch (5) and the transient overvoltage protection (1) is provided between the switch and the network. The circuit arrangement also has a network voltage analysis unit (3), which is connected to the switch on the control side so that the switch can be tripped and is also connected to the reconnection unit (4), and also has a voltage supply assembly (2) connected to the network. According to the invention, the switch is an instantaneously tripping, mechanical, low-inductance switch and is designed to conduct pulse currents; the energy required to trip the switch is provided by an energy storage unit irrespective of the network state and of the phase position, and there are different overvoltage protection functions depending on the switch position.