Transformer Turns Testing Circuit for High-Ratio Coil Detection
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Solution Overview
Problem
Existing transformer testing devices struggle to accurately determine the number of coil turns, especially in transformers with high turns ratios such as current transformers and high-voltage transformers, where detecting differences of one turn is difficult.
Innovation Solution
A transformer turns number testing circuit that connects primary-side coils of a reference transformer and a to-be-tested transformer in phase and series, and secondary-side coils in phase and series, incorporating a reference-side resistance element, a to-be-tested-side resistance element, and a voltage detection resistance element in a common line to detect voltage differences and phase differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional testing device uses differential voltage amplification to test transformer turns ratio, then it can test standard transformers, but it cannot accurately detect turn differences in high turns ratio transformers (200:1, 400:1)
Solution Approach 1:
The patent divides the testing circuit into two separate loop circuits: a reference-side loop circuit and a to-be-tested-side loop circuit. Each loop has its own resistance element and is connected to the primary and secondary coils independently. This segmentation allows each loop to be optimized for specific measurement conditions, enabling accurate detection of small voltage differences in high turns ratio transformers while maintaining compatibility with standard transformers.
Solution Approach 2:
The patent introduces resistance elements as intermediary components in each loop circuit. These resistance elements convert the small voltage differences induced by turn variations into measurable voltage drops. By using resistance elements as mediators between the transformer coils and the measurement system, the circuit can detect minute differences in high turns ratio transformers that would otherwise be undetectable with conventional direct voltage measurement methods.
2Loss of information
If the secondary sides of transformers are connected with induced voltages in opposite directions for differential measurement, then voltage differences can be extracted, but the measurement becomes inaccurate for high turns ratio transformers
Solution Approach 1:
Instead of connecting secondary sides with opposite directions to create differential voltage, the patent inverts the approach by connecting primary sides in series with the same polarity and measuring the voltage difference across secondary sides. This inversion of the conventional connection method allows the circuit to maintain balanced current flow while detecting small voltage differences caused by turn variations, thereby improving measurement accuracy for high turns ratio transformers.
Solution Approach 2:
The patent creates equipotential conditions by connecting primary sides in series with the same polarity, ensuring that the same current flows through both primary coils. This equipotential approach at the primary side allows any voltage difference measured at the secondary side to be directly attributed to differences in turns ratio, eliminating measurement errors that would arise from unequal current distribution.
3Device complexity
If a single loop circuit is used for testing, then the circuit structure is simple, but it cannot provide accurate measurements for both standard and high turns ratio transformers
Solution Approach 1:
The patent designs a universal testing circuit that can accurately measure both standard transformers and high turns ratio transformers through its dual-loop structure. Each loop is configured to handle specific measurement requirements, yet the overall system provides unified measurement capability across different transformer types. The circuit achieves multi-functionality by allowing flexible configuration of resistance elements and loop connections to suit different turns ratio ranges.
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 accurate testing of coil turns in transformers with high turns ratios by detecting voltage and current differences through the voltage detection resistance element, effectively determining matching or non-matching coil turns.
Implementation Method 1
secondary sides of a to-be-tested transformer and a standard transformer, primary sides of which are connected to an AC power supply, are connected so that induced voltages are in opposite directions, and a differential voltage thereof is amplified and extracted
Data Source
AI summary
Provided is a circuit capable of accurately testing the number of coil turns even with a transformer having a high turns ratio.A transformer turns number testing circuit (1) is configured to be able to connect primary-side coils (Np1 and Np2) and secondary-side coils (Ns1 and Ns2) of a reference transformer (CT1) and a to-be-tested transformer (CT2) in phase and in series, and includes: a reference-side resistance element (R1) included in a reference-side loop circuit (Lp1) formed between both ends of the secondary-side coil of the reference transformer; a to-be-tested-side resistance element (R2) included in a to-be-tested-side loop circuit (Lp2) formed between both ends of the secondary-side coil of the to-be-tested transformer; and a voltage detector (Rd) provided in a common line of the reference-side loop circuit and the to-be-tested-side loop circuit, the common line connecting a midpoint between the secondary-side coils of the reference transformer and the to-be-tested transformer and a midpoint between the reference-side resistance element and the to-be-tested-side resistance element.