Vacuum Interrupter Point-on-Wave Closing to Limit Contact Arcing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing switching devices employing vacuum interrupters experience contact arcing and damage due to high fault currents during closing operations, particularly when commanded to close with high voltage potential, leading to contact bouncing and potential welding.
Innovation Solution
Adjusting the point on wave closing of the vacuum interrupter to generate a minor current loop that minimizes accumulated current during the closing operation by selecting an optimal voltage angle for initiating the closing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the vacuum interrupter is commanded to close with high voltage potential during fault conditions, then the switching device can restore power quickly, but contact arcing and damage occur due to high fault currents
Solution Approach 1:
The system determines bounce characteristics of the contacts before initiating the closing operation. This preliminary characterization of contact behavior allows the control system to predict and compensate for potential contact bouncing, selecting an optimal voltage angle that prevents excessive arcing while maintaining fast closing speed for power restoration.
Solution Approach 2:
The invention changes the parameter of closing voltage angle selection based on determined bounce characteristics. By adjusting which voltage angle on the AC wave is used to initiate closing, the system optimizes the current loop characteristics to minimize accumulated current during contact bounce, thereby reducing arcing damage while maintaining productivity.
2Device complexity
If the closing operation is initiated at a standard voltage angle, then the switching device operates simply, but accumulated current during contact bounce causes contact welding
Solution Approach 1:
The control system uses feedback from the determined bounce characteristics to adjust the closing voltage angle selection. This feedback mechanism allows the system to adaptively select the optimal voltage angle that minimizes accumulated current during contact bounce, preventing contact welding while maintaining relatively simple device architecture.
3Loss of time
If the vacuum interrupter closes quickly to isolate faults, then fault isolation is rapid, but mechanical stress on the vacuum interrupter increases
Solution Approach 1:
By changing the voltage angle parameter at which closing is initiated, the system optimizes the current loop characteristics to minimize accumulated current during contact bounce. This reduction in current accumulation decreases the mechanical stress and electromagnetic forces on the vacuum interrupter contacts during rapid closing, enabling fast fault isolation with reduced mechanical stress.
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
Reduces contact arcing damage and minimizes the accumulation of current, thereby preventing contact welding and mechanical stress on vacuum interrupters.
Implementation Method 1
When the vacuum interrupter is opened by operating the magnetic actuator to move the movable contact away from the fixed contact to prevent current flow through the interrupter a plasma arc is created between the contacts that is contained and quickly extinguished by the vacuum at the next zero current crossing.
Implementation Method 2
a plasma arc is created between the contacts that is contained and quickly extinguished by the vacuum at the next zero current crossing
Implementation Method 3
The magnetic actuator used in these types of switching devices typically have an armature or plunger that is moved by an electrical winding wound on a stator to open and close the vacuum interrupter contacts
Implementation Method 4
The current is then turned off to de-energize the coil and permanent magnets hold the plunger against the latching plate and against a compression force of an opening spring and the compliance spring
Data Source
AI summary
A system and method for point on wave closing of a switching device, where the close initiation point is selected so that a minor current loop is generated that minimizes the accumulated current during the closing operation. The method includes determining bounce characteristic of contacts in the switching device during the closing operation, identifying available close initiation points on a voltage wave for a voltage across the contacts, selecting one or two of the close initiation points on the voltage wave that minimizes the accumulation of current during the closing operation, and closing the switching device using the selected close initiation point.