Power Device Short-Circuit Switch for Voltage Protection

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Solution Overview

Problem

In high-voltage AC power systems, maintaining the energized state during maintenance of power devices like gas insulated switchgear poses a risk of excessive voltage induction in coils, potentially leading to breakage when the fan and drive device are stopped for inspection or replacement.

Innovation Solution

A power device design incorporating a short-circuit switch within a sealed container filled with insulating fluid, where the short-circuit switch short-circuits the output from a power generation unit to prevent excessive voltage induction, ensuring reliable operation even when the device is stopped.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of repair

If the output terminal of the coil is opened during maintenance to stop the fan and drive device, then the maintenance can be performed, but the resistance at the output terminal becomes infinite which induces excessive voltage in the coil and may break the coil

Engineering Contradiction:

Improvemaintenance capabilityVSAvoidcoil integrity

Core Design Contradiction:

Ease of repairVSReliability

Solution Approach 1:

The short-circuit switch is pre-configured in parallel with the power device unit. Before maintenance begins, the switch can be activated to short-circuit the coil output terminals, preventing excessive voltage induction. This preliminary protective action ensures that when the power device unit is disconnected for maintenance, the coil is already protected from voltage spikes that would occur with open terminals.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The short-circuit switch acts as an intermediary component between the coil and the power device unit. It provides an alternative current path that mediates the transition between operational and maintenance states, allowing the coil to remain connected to a load (the short-circuit path) even when the power device unit is disconnected, thereby preventing open-terminal conditions.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Duration of action of moving object

If the fan and drive device are stopped for maintenance inspections or replacement, then the maintenance can be performed, but the energized state must be maintained which causes the coil output terminal to open and induce excessive voltage

Engineering Contradiction:

Improvecontinuous operation durationVSAvoidexcessive voltage induction

Core Design Contradiction:

Duration of action of moving objectVSObject-affected harmful factors

Solution Approach 1:

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The short-circuit switch converts the potentially harmful open-terminal condition into a beneficial protected state. By providing a deliberate short-circuit path, the system transforms what would be a dangerous voltage spike scenario into a safe maintenance condition, where the coil current is safely diverted through the switch rather than creating excessive voltage.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 implementation of a short-circuit switch effectively prevents excessive voltage induction in the power generation unit, enhancing the reliability of the power device by allowing it to maintain the energized state without risking coil breakage during maintenance.

Implementation Method 1

a power generation unit configured to generate power that is induced by a magnetic flux of a current flowing through the energizing conductor

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

an insulating fluid being enclosed in the sealed container

Methodology Applied

Scientific EffectElectrical insulation: Dielectric

Data Source

PatentUS10535984B2Power device including a short-circuit switch and a separation switch

Publication Date: 2020.01.14 MITSUBISHI ELECTRIC CORP

AI summary

A power device, which includes: an energizing conductor; a power generation unit configured to generate power that is induced by a magnetic flux of a current flowing through the energizing conductor; a power device unit configured to use the power generated in the power generation unit as a power source; a short-circuit switch capable of short-circuiting an output from the power generation unit; and a sealed container in which the energizing conductor, the power generation unit and the power device unit are included, and an insulating fluid is enclosed in the sealed container. This power device is provided as a highly reliable power device, which is used in an AC power system and does not induce an excessive voltage in the power generation unit when the power device unit is stopped in the state where the energized state of the energizing conductor is maintained.