Capacitor Protection Device with Torsion Spring Breaking Mechanism

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Solution Overview

Problem

Existing capacitor protection devices rely on the force and speed of decomposition gas pressure to break fuses, which can be inconsistent and inadequate for effectively managing pressure surges in self-healing capacitors, leading to potential casing rupture.

Innovation Solution

A protection device with a fracturable conductor and a mobile part that accumulates energy via a torsion spring, actuated by pressure exceeding a trigger threshold, using a knife holder and locking/unlocking mechanism to ensure consistent breaking of the conductor, even in high-pressure situations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a fuse is used to break when pressure exceeds a threshold, then the device can protect against pressure surges, but the breaking force and speed depend on gas pressure and rise rate which can be inconsistent and inadequate

Engineering Contradiction:
Improveprotection reliabilityVSAvoidbreaking force
Core Design Contradiction:
ReliabilityVSForce

Solution Approach 1:

The spring is pre-loaded to accumulate elastic potential energy before the fault occurs. When the piston moves due to pressure surge, it releases this pre-stored energy to break the fuse, ensuring sufficient breaking force regardless of the pressure rise rate.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The spring-piston mechanism converts the continuous pressure force into a periodic impulsive action. The spring compresses during normal operation and then releases energy in a sudden impulse when triggered, providing the necessary high-speed breaking action.

Inventive Principle:
Principle #19Periodic action

2Reliability

If a fuse is used to break when pressure exceeds a threshold, then the device can protect against pressure surges, but the breaking speed depends on gas pressure and rise rate which can be insufficient

Engineering Contradiction:
Improveprotection reliabilityVSAvoidbreaking speed
Core Design Contradiction:
ReliabilityVSSpeed

Solution Approach 1:

The spring is pre-loaded to accumulate elastic potential energy before the fault occurs. When the piston moves due to pressure surge, it releases this pre-stored energy to break the fuse, ensuring sufficient breaking speed regardless of the pressure rise rate.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The spring-piston mechanism converts the continuous pressure force into a periodic impulsive action. The spring compresses during normal operation and then releases energy in a sudden impulse when triggered, providing the necessary high-speed breaking action.

Inventive Principle:
Principle #19Periodic action

3Adaptability or versatility

If the breaking force depends on decomposition gas pressure, then the device can respond to pressure changes, but the force available is inconsistent and may be inadequate for high-pressure situations

Engineering Contradiction:
Improvepressure responseVSAvoidprotection consistency
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The spring acts as an intermediary between the pressure force and the fuse-breaking action. It converts the variable pressure force into a consistent, pre-loaded elastic energy that reliably breaks the fuse regardless of pressure variations.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The system changes the physical parameter from direct pressure force to stored elastic potential energy. This transformation makes the breaking force independent of pressure variations, ensuring consistent protection across different operating conditions.

Inventive Principle:
Principle #35Parameter changes

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 device ensures reliable and consistent breaking of the fracturable conductor, preventing capacitor casing rupture by releasing stored energy with sufficient speed and force to manage pressure surges effectively, enhancing the safety and reliability of self-healing capacitors.

Implementation Method 1

the energy accumulation means may comprise a torsion spring mounted between the knife holder and the case, said spring being charged when the knife holder is in a cocked position

Methodology Applied
Scientific EffectTorsion spring: Torsion Spring

Implementation Method 2

a mobile part which can be moved under the effect of the pressure in the envelope, in a movement in translation along a longitudinal axis, said movable part being mounted so as to actuate the breaking means when the pressure exceeds a trigger threshold

Methodology Applied
Scientific EffectPressure: Pressure Increase

Data Source

PatentEP2073224B1Capacitor protection device
Publication Date: 2013.12.11 SCHNEIDER ELECTRIC IND SAS
  • EP2073224B1 patent drawingFigure 1~3
  • EP2073224B1 patent drawingFigure 4
  • EP2073224B1 patent drawingFigure 5~6

AI summary

The device (11) has a case mounted on an envelope of a capacitor, and a breakable conductor (41) mounted in series with one of armatures of the capacitor. A piston type movable part (18) is displaceable in translation movement along a longitudinal axis under the effect of pressure in the envelope, and is mounted in a manner to actuate a rupture unit when the pressure exceeds a triggering threshold. The rupture unit has a torsion spring (53) for accumulating energy required to break the conductor, and locking and unlocking units for releasing the energy when the rupture unit is actuated.