Surge Suppressor with High Impedance Filter and SCR Switching

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Solution Overview

Problem

Conventional surge suppressing devices fail to detect and suppress transient voltage events early enough, potentially damaging connected equipment, and have a short capacitor lifespan due to constant high voltage charging, necessitating a crowbar circuit for protection during voltage swells.

Innovation Solution

A surge suppressor utilizing a high impedance high pass filter, series inductors, and capacitor banks, which detects surges before output voltage rises, keeping capacitors discharged to extend lifespan and eliminating the need for a crowbar circuit by only activating during high frequency events.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional L-C filter is used for surge suppression, then the device can suppress transient voltage events, but the detection occurs after the output line voltage has already begun to rise, potentially damaging connected equipment

Engineering Contradiction:
Improveequipment protectionVSAvoidsurge detection time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent applies preliminary action by detecting surge events before they reach the output line through a detection circuit positioned before the L-C filter. The detector monitors the input line voltage and triggers the capacitor bank before the surge propagates to the output, preventing voltage rise at the equipment side rather than reacting after detection at conventional points.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent introduces an intermediary detection circuit and trigger mechanism between the input line and the L-C filter. This intermediary system detects surges on the input line and activates the capacitor bank in advance, serving as a mediator that enables early suppression before the surge affects the output line and connected equipment.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If a capacitor within the bridge rectifier circuit is kept charged to the peak level of the incoming AC line voltage, then the device can maintain readiness for surge suppression, but the capacitor lifespan is reduced due to constant high voltage stress

Engineering Contradiction:
Improvesurge suppression readinessVSAvoidcapacitor lifespan
Core Design Contradiction:
ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The patent applies dynamics by transitioning the capacitor bank from a static charged state to a dynamic switched state. Instead of keeping capacitors continuously charged to peak voltage, the system dynamically switches capacitors into the circuit only when surge detection triggers the SCR, allowing the capacitor bank to adapt its charge state based on actual surge conditions rather than maintaining constant high voltage stress.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the voltage parameter across the capacitor bank by using SCR to switch capacitors into circuit only during surge events. The capacitor voltage transitions from near-zero during normal operation to charged state during surges, rather than maintaining constant peak voltage. This parameter change reduces cumulative voltage stress and extends capacitor lifespan while maintaining suppression readiness.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If a crowbar circuit is employed before the L-C filter to protect during high voltage swells, then the surge suppressor is protected, but the device complexity increases and the crowbar circuit is required to disconnect and manually reset

Engineering Contradiction:
Improvesurge suppressor protectionVSAvoidcircuit configuration
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies multi-functionality by having the capacitor bank serve dual purposes: suppressing surge events and protecting against voltage swells. The same capacitor bank that suppresses transient surges also limits voltage during prolonged swells by remaining in circuit to shunt excess current, eliminating the need for a separate crowbar circuit and reducing overall device complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent merges the surge suppression function and voltage swell protection function into a single integrated system. The capacitor bank performs both functions, and the detector-trigger-capacitor combination replaces the separate crowbar circuit, consolidating multiple protection mechanisms into one unified system that reduces complexity rather than adding components.

Inventive Principle:
Principle #5Merging (Combining)

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 effectively limits output voltage, significantly extending capacitor lifespan and eliminating the need for a crowbar circuit, while ensuring equipment protection during voltage swells, with a six-fold increase in capacitor lifespan and enhanced protection against high frequency surges.

Implementation Method 1

a high impedance high pass filter

Methodology Applied
Scientific EffectHigh pass filter: Filter (electronic)

Implementation Method 2

one or more series inductors

Methodology Applied
Scientific EffectInductance: Inductor

Implementation Method 3

one or more capacitor banks

Methodology Applied
Scientific EffectCapacitance: Capacitance

Implementation Method 4

two SCRs (Silicon-Controlled Rectifiers)

Methodology Applied
Scientific EffectSilicon-Controlled Rectifier switching: Diode

Data Source

PatentEP2701259B1Series type surge suppressor and clamping circuit
Publication Date: 2020.09.16 LEGRAND AV INC
  • EP2701259B1 patent drawingFigure 1
  • EP2701259B1 patent drawingFigure 2A~2B
  • EP2701259B1 patent drawingFigure 3

AI summary

Various embodiments relate to a degrade-resistant surge suppressor that detects and suppresses surge events. The surge suppressor includes a high impedance high pass filter (110), one or more series inductors (120), and one or more capacitor banks (130, 140). The capacitor bank may include a bridge rectifier circuit having two diodes and two SCRs (Silicon-Controlled Rectifiers; 131, 132, 134), or a diode bridge rectifier (131) fed by a TRIAC (Triode for Alternating Current; 138). The surge suppressor may further include a secondary trigger device (152, 154) to ensure proper attenuation of surge events.