Transformer Test System Using Switched DC Excitation
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Solution Overview
Problem
Existing transformer testing methods struggle to accurately measure transformer turns ratio, winding resistance, and no-load losses, especially in three-phase transformers, due to limitations in excitation methods and measurement accuracy.
Innovation Solution
A system and method utilizing a turns ratio meter with a switching matrix, measurement circuit, and processor to perform step-down and step-up testing using switched DC excitation, allowing for accurate measurement of transformer characteristics without rearranging test leads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional transformer testing methods are used, then testing can be performed on transformers, but measurement accuracy of turns ratio, winding resistance, and no-load losses is insufficient
Solution Approach 1:
The patent applies parameter changes by using switched DC excitation instead of traditional AC excitation, and by implementing multiple measurement configurations (step-down and step-up testing) to accurately determine transformer characteristics. The system measures voltage and current under different excitation conditions to calculate precise turns ratio, winding resistance, and no-load losses, resolving the contradiction between measurement precision and reliability.
2Productivity
If step-down and step-up testing are performed without rearranging test leads, then testing efficiency is improved, but device complexity increases due to switching matrix requirements
Solution Approach 1:
The patent implements universality by designing a multi-functional testing system that can perform both step-down and step-up testing configurations using the same physical test leads and measurement circuitry. The switching matrix enables the system to reconfigure connections dynamically, allowing one testing apparatus to serve multiple testing purposes without requiring separate test lead arrangements for each testing mode.
Solution Approach 2:
The switching matrix acts as an intermediary component that mediates between the fixed test leads and the measurement circuits. It enables flexible connection reconfiguration without requiring physical rearrangement of test leads, thus improving testing efficiency while containing device complexity within the manageable switching matrix component.
3Measurement precision
If switched DC excitation is used for transformer testing, then measurement accuracy of transformer characteristics is improved, but energy loss increases during testing
Solution Approach 1:
The patent applies periodic action by using switched DC excitation that is applied in controlled intervals and sequences. The system performs step-down and step-up testing in alternating phases, with excitation applied only when measurements are being taken. This periodic excitation approach maintains measurement accuracy while minimizing energy loss by avoiding continuous excitation during the entire testing process.
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
Enables precise determination of transformer turns ratio, winding resistance, and no-load losses, improving measurement accuracy and efficiency, especially for three-phase transformers under various excitation conditions.
Implementation Method 1
an alternating electric voltage in a primary winding creates a fluctuating electro-magnetic field that couples into the secondary winding, thereby inducing a corresponding alternating electric voltage in the secondary winding
Implementation Method 2
the primary and secondary windings are wound on a common core that improves the efficiency of the transformer by concentrating the electro-magnetic field within the common core
Implementation Method 3
the core may have losses in the form of hysteresis or eddy currents
Implementation Method 4
the core may have losses in the form of hysteresis or eddy currents
Implementation Method 5
The lost power, be it in the insulation of the transformer or in the magnetic circuit of the core, may manifest itself in the form of heat
Data Source
AI summary
A transformer windings impedance meter. The meter comprises a switching matrix; a plurality of field effect transistors (FETs); a measurement circuit; a test output circuit; and a processor coupled to the switching matrix, the plurality of FETs, the measurement circuit, and the test output circuit, wherein the processor is configured to configure the switching matrix in a first configuration, apply a short circuit to a first side of a transformer, where the short circuit is completed through at least one of the plurality of FETs, apply a first alternating current (AC) excitation to a second side of the transformer, while continuing to apply the first AC excitation to the second side of the transformer, measure a first voltage and a first current in the second side of the transformer, and determine an impedance of the second side of the transformer based on the first voltage and the first current.