Reduced Size Fault Interrupter Pole Unit
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Solution Overview
Problem
Existing switchgear pole units require significant air gaps for electrical isolation between the vacuum interrupter switch at medium voltage line potential and the electromagnetic actuator at ground potential, leading to increased size and weight, which hinders installation and handling due to space and access limitations.
Innovation Solution
A pole unit configuration where the vacuum interrupter switch, electromagnetic actuator, and receiver coil are all at line potential, with a transmitter coil at ground potential, utilizing wireless power transfer coils to eliminate the need for an air gap, allowing for reduced size and weight by eliminating the electrical isolation gap.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrical isolation air gap is provided between the vacuum interrupter switch and electromagnetic actuator, then electrical safety is ensured, but the size and weight of the pole unit increase significantly
Solution Approach 1:
The electromagnetic actuator is electrically isolated from ground potential and brought to line potential, matching the potential of the vacuum interrupter switch. This eliminates the voltage difference that necessitates the air gap, allowing direct physical coupling while maintaining electrical safety. The actuator coil is energized through capacitive coupling from the bellows, which are at line potential, ensuring the entire assembly operates at the same electrical potential.
Solution Approach 2:
The bellows structure serves as an intermediary that provides both mechanical movement transmission and electrical isolation. The bellows are capacitively coupled to the actuator coil, allowing electrical energy transfer while maintaining the equipotential relationship. This intermediary enables the actuator to function at line potential without direct connection to ground potential control electronics.
2Reliability
If electrical isolation air gap is provided between the vacuum interrupter switch and electromagnetic actuator, then electrical safety is ensured, but the volume of the pole unit increases
Solution Approach 1:
By bringing the electromagnetic actuator to line potential through capacitive coupling via the bellows, the voltage difference between the actuator and interrupter switch is eliminated. This removes the need for a large air gap, significantly reducing the pole unit volume while maintaining electrical safety through the capacitive coupling mechanism.
Solution Approach 2:
The electromagnetic actuator is positioned within the vacuum interrupter switch housing, with the actuator rod extending into the vacuum chamber. This nested arrangement eliminates the need for separate isolation space, allowing compact integration of components while maintaining electrical safety through the equipotential design.
3Ease of operation
If smaller pole unit size is used, then installation and handling become easier, but electrical isolation between components becomes more difficult to ensure
Solution Approach 1:
The fundamental solution is to make the electromagnetic actuator equipotential with the vacuum interrupter switch by operating both at line potential. This eliminates the need for physical separation while maintaining electrical safety. The capacitive coupling through the bellows provides the necessary electrical isolation mechanism without requiring large air gaps, enabling compact design with maintained safety.
4Ease of operation
If the actuator is electrically isolated from the switch, then ground potential interface is enabled, but significant air gap is required
Solution Approach 1:
Instead of isolating the actuator at ground potential from the line potential switch, the approach is inverted: the actuator is brought to line potential and electrically coupled to the switch. Control electronics at ground potential interface with this line potential actuator through standard isolation techniques, eliminating the need for large air gaps while maintaining the ground potential interface capability.
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
This configuration reduces the size and weight of the pole unit, enhancing mechanical performance and handling by eliminating the air gap, making the switchgear easier to maneuver and install in constrained spaces.
Implementation Method 1
a power assembly having a transmitter coil and a receiver coil that are electromagnetically coupled
Implementation Method 2
When the interrupter switch is opened by moving the movable contact away from the fixed contact the arc that is created between the contacts is quickly extinguished by the vacuum
Implementation Method 3
a spring positioned against the rod and applying a spring bias
Data Source
Figure 1
Figure 2~3
AI summary
A pole unit including a vacuum interrupter switch having a fixed contact extending into one end of a vacuum chamber and being electrically coupled to a first terminal, and a moving contact extending into an opposite end of the chamber. A sliding contact is rigidly coupled to the moving contact and slidably coupled to a second terminal. The pole unit also includes an electromagnetic actuator including a coil, a rod coupled to the sliding contact and a spring positioned against the rod. The pole unit further includes a transmitter coil and a receiver coil that are electromagnetically coupled, where the receiver coil is electrically coupled to the actuator and is electrically isolated from the transmitter coil. In this configuration, the interrupter switch, the actuator and the receiver coil are at a line potential and the transmitter coil is at ground potential.