External Rogowski Sensing for Transformer Winding Fault Detection
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Solution Overview
Problem
Current fault identification systems in electrical distribution transformers, particularly those using Rogowski sensors, require invasive installation and can be prone to false activations due to current sensor saturation, limiting their effectiveness in real-time fault detection without opening the transformer.
Innovation Solution
An apparatus and method utilizing a first Rogowski current sensor at a high-voltage incoming current terminal and a second Rogowski current sensor in tandem at a low-voltage outgoing and incoming current terminal, integrated with an integrating circuit, programmable memory, communication module, and controller to monitor and compare transformation ratios, enabling fault detection without opening the transformer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Rogowski sensors are installed inside the transformer tank, then fault detection can be performed, but the installation is invasive and requires opening the transformer
Solution Approach 1:
The patent extracts the Rogowski sensors from the transformer interior and places them on external conductors. The sensors are positioned around conductors that carry transformer current but are accessible from outside the transformer tank, eliminating the need to open the transformer for installation while maintaining the ability to detect internal faults through current measurement
Solution Approach 2:
The patent uses external conductors as intermediaries to transmit transformer current to the Rogowski sensors. The sensors measure current in these conductors, which carry the same current as the transformer windings, allowing indirect measurement of transformer current without physical contact with internal components
2Measurement precision
If a lower differential threshold is used to increase sensitivity, then more faults can be detected, but the system may be falsely activated by non-fault events
Solution Approach 1:
The patent implements a control system that continuously monitors the transformation ratio and compares it against the allowed threshold. The system provides feedback by generating fault signals when deviations are detected, allowing for real-time adjustment and verification of fault conditions rather than simple threshold triggering
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 solution allows for accurate and non-invasive fault identification in distribution transformer windings, reducing false activations and enabling real-time monitoring of transformation ratios to detect faults effectively.
Implementation Method 1
A first Rogowski current sensor adapted to be placed on a primary conductor connected to a high-voltage incoming current terminal to detect a primary incoming current
Data Source
AI summary
An apparatus for identifying a fault in the windings of a distribution transformer, a transformer, and an associated method, said device comprising: a first Rogowski current sensor at a high-voltage incoming current terminal, and a second Rogowski current sensor in tandem at a low-voltage outgoing current terminal and at a low-voltage incoming current terminal; a first conductor of the low-voltage outgoing current terminal, passed through in one direction through the second sensor, and a second conductor of the low-voltage incoming current terminal, passed through in the opposite direction through the second sensor; the first and second sensors generate output signals indicating the primary current and the secondary current; both signals are integrated, generating output signals proportional to the primary current and the secondary current, obtaining a transformation ratio, which is compared with a threshold, and sending a fault signal if said threshold is exceeded.