Title :
A current-dividing highly stable DC current transformer using a magnetic modulator
Author :
Abe, Minoru ; Nakazoe, Jun
Author_Institution :
Dept. of Electron. & Commun. Eng., Musashi Inst. of Technol., Tokyo, Japan
fDate :
12/1/1989 12:00:00 AM
Abstract :
A highly stable DC transformer system has been developed to control large currents to 1 p.p.m. It uses a resistive current divider and two magnetic-modulator ampere-turn comparators with feedback. The comparators are operated just below flux density saturation. This prevents input transients from disrupting the feedback control. The main comparator has a relatively small core operating at low magnetomotive force due to a small current, provided by the resistive divider. The subcomparator corrects changes in the small current by changing the resistor values. A 20-A regulated current source achieves 1 p.p.m./6 h for ambient temperatures controlled to +0.25°C
Keywords :
comparators (circuits); constant current sources; current transformers; dividing circuits; power supplies to apparatus; 20 A; DC current transformer; feedback; feedback control; magnetic modulator; magnetic-modulator ampere-turn comparators; magnetomotive force; regulated current source; resistive current divider; Circuit faults; Control systems; Current transformers; Feedback control; Magnetic cores; Magnetic flux; Resistors; Saturation magnetization; Temperature control; Transformer cores;
Journal_Title :
Instrumentation and Measurement, IEEE Transactions on
