Circuit Breaker Plausibility Comparison for Transformer Fault Detection
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Solution Overview
Problem
Existing power distribution switches, particularly for low voltages, face issues with faulty instrument transformers leading to incorrect measurement signals due to wire fractures or shorts, which can result in failure to identify tripping situations, making it complex to test them during operation.
Innovation Solution
The solution involves recording currents and voltages from power converters and performing a plausibility comparison with instrument transformers, generating a warning or tripping signal when non-plausibility is detected, thereby identifying faults in combination instrument transformers through cost-effective measurements and informing the user.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If complex testing procedures are implemented to detect instrument transformer faults, then measurement accuracy can be verified, but the complexity and cost of testing increases
Solution Approach 1:
The switch performs self-diagnosis by automatically comparing its own measurement signals from the instrument transformer against the power converter current signals. This self-service approach eliminates the need for external complex testing equipment and procedures, as the system continuously monitors itself during normal operation.
Solution Approach 2:
The system monitors changes in the relationship between power converter current and instrument transformer current over time. By analyzing parameter deviations and trends, the system can detect instrument transformer faults through simple threshold comparisons rather than requiring complex diagnostic tests.
2Reliability
If continuous monitoring of power converter currents is implemented, then faults can be identified early, but the complexity of the electronic circuit increases
Solution Approach 1:
The electronic circuit performs multiple functions using the same hardware components: it monitors power converter current for both protective tripping purposes and plausibility comparison purposes. The instrument transformer current is also used for both normal measurement functions and fault detection through deviation analysis, eliminating the need for separate dedicated monitoring hardware.
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 approach enhances the functional reliability of the switch by allowing for easy identification of faults in instrument transformers, ensuring accurate tripping signals and immediate protection of connected loads.
Implementation Method 1
The electrical power for the release's own power supply is taken by way of electrical power converters (generally iron-core transformers) from the phase currents to be monitored, to be precise via the magnetic fields, based on the transformer principle
Implementation Method 2
Current sensors in the form of instrument transformers are used to record the individual phase currents, that is to say for the actual current recording/measurement, and generally use an air-cored coil (Rogowski converter), converting the magnetic field of the associated phase conductor to a measurement signal which is proportional to the current differentiated with respect to time
Data Source
AI summary
A switch is disclosed for power distribution, in particular a circuit breaker and compact switch, which automatically interrupts the electric currents flowing through the switch in a polyphase electrical power supply system when a tripping situation occurs. In at least one embodiment, the switch includes switching contacts which are provided for each phase and can be opened via a switching shaft; an electronic release which automatically initiates the opening of the switching contacts via the switching shaft; electrical power converters, which in each case take the electrical power which is required for the electrical power supply for the release from the currents for the individual phases; instrument transformers which convert the currents in each of the individual phases to a measurement signal; an electronic circuit, in particular in the form of a microprocessor, for assessment of the current values which correspond to the measurement signals, wherein the occurrence of the tripping situation is in each case identified on the basis of the assessment. In order to improve the functional reliability of the switch, in at least one embodiment it is proposed that the currents emitted from the power converters are additionally recorded and that the electronic circuit carries out a plausibility comparison on the basis of the recorded current of the power converters and of the instrument transformers, and generates a warning signal in the event of non-plausibility.