Heavy DC sensing theory and double magnetic detector

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Heavy DC sensing theory and double magnetic detector

On-line measurement of heavy dc current has been studied for many years, and devices based on magnetic modulator, magnetic amplifier, optic-fiber have been developed, but harsh environments made all of them are insufficient for on-line measurement. A new sensing theory using magnetic modulator and magnetic amplifier is discussed. The open-loop characteristic of the double detector has only one operating point corresponding to zero ampere turns. The double detector comparator possesses not only high precision, low drift, high linearity and good antimagnetic property from magnetic modulator comparators, but also the perfect stability and reliability from magnetic amplifiers. A double dc comparator with a ratio of 5 000A/1A has been constructed for testing and performance evaluation. The performance and test results show: The error of the double detector dc comparator measured with stable dc currents between 10% and 100% rated current is less than 5×10-5. The double detector dc comparator has successfully achieved rapid and accurate dc step response at 10 000A which is twice over the rated current, which shows the fire-new detector has perfect stability and reliability.