Vacuum Switch Self-Testing via Four-Quadrant Controller Pulses
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Solution Overview
Problem
The existing methods for testing the functionality of a vacuum switch in a traction converter require a test device, necessitating disconnection from high-voltage equipment and resulting in significant effort, downtime, and potential consequential damage if not performed regularly, limiting the testing to a railway or tram depot.
Innovation Solution
The method involves controlling the four-quadrant controller to generate a voltage pulse timed relative to the mains AC voltage, allowing a test voltage to be applied across the vacuum switch without a test device, using the traction converter's energy storage to check for current flow, indicating the switch's functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a test device is used to test the vacuum switch, then the functionality can be checked, but the vacuum switch must be disconnected from high-voltage equipment, requiring significant effort and downtime
Solution Approach 1:
The traction converter tests the vacuum switch using its own internal components (four-quadrant controller, intermediate circuit capacitor, mains AC voltage) without requiring external test devices. The controller generates test voltage pulses and detects leakage currents, enabling the system to self-diagnose vacuum switch functionality while remaining connected to high-voltage equipment, thus eliminating downtime and disconnect/ reconnect operations
Solution Approach 2:
The four-quadrant controller performs both its normal control function and the additional function of vacuum switch testing. By generating voltage pulses and measuring leakage currents, the controller multiplies its functionality, allowing the same device to serve multiple purposes without requiring separate dedicated test equipment
2Reliability
If a test device is used to test the vacuum switch, then the functionality can be checked, but extensive precautionary measures and special test devices are required
Solution Approach 1:
The system uses its own existing components for testing rather than external specialized equipment. The four-quadrant controller, intermediate circuit capacitor, and vacuum switch itself form a self-contained test system that eliminates the need for complex external test devices with high-voltage transformers and specialized insulation
Solution Approach 2:
The testing function is merged with the existing control circuitry of the traction converter. The four-quadrant controller integrates both control and testing operations, combining multiple functions into a single system rather than requiring separate dedicated test equipment
3Reliability
If the vacuum switch is tested regularly, then faults can be detected early, but the testing process is complex and time-consuming
Solution Approach 1:
The vacuum switch testing is performed automatically by the traction converter's own controller without requiring manual intervention or specialized test personnel. The system autonomously generates test voltage pulses, measures leakage currents, and detects faults, significantly improving testing efficiency and productivity while maintaining reliable fault detection
Solution Approach 2:
The four-quadrant controller continuously monitors leakage current during testing and provides feedback to detect vacuum switch faults. This automated feedback mechanism enables rapid fault detection without manual analysis, improving both reliability and productivity by eliminating time-consuming manual testing procedures
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 method enables functional testing of the vacuum switch anywhere, anytime, without a test device, simplifying fault detection and reducing effort, as it utilizes existing circuit components, ensuring the vacuum switch's functionality without physical separation from high-voltage equipment.
Implementation Method 1
The energy of the intermediate circuit capacitor of the voltage intermediate circuit of the traction converter is used to generate such a voltage pulse
Implementation Method 2
If the vacuum switch is not able to insulate, a current flows from the supply network to the four-quadrant controller, which current is recorded by the four-quadrant controller measuring the measured values
Data Source
AI summary
The method involves parallely connecting a network-side four-quadrant controller and a pulse power converter. A primary winding of a traction transformer is connected with network-alternating current (AC) voltage by a vacuum switch that is represented as a transmission path (28). The controller is controlled by the opened switch when the voltage temporally lies relative to controller input voltage such that a differential voltage between the AC and input voltages corresponds to a preset test voltage. A determination is made to find whether current flows from a supply network to the controller.