U.S. Philips Corporation

Hendrikus Fransiscus Bloemen

Theodorus J Van Kessel

Eric Henricus Stulemeijer

Johannes Maria Pieper

A current measuring arrangement including a measuring resistor can be protected against excess currents by means of a PTC-resistor and an amplifier circuit. This protection is self-restoring in contrast to the conventional series-connected safety fuse. The amplifier circuit, the PTC-resistor and the measuring resistor may be arranged so that the property of zero voltage drop of a known circuit arrangement is maintained.

Current-measuring arrangement with overload protection

A measuring arrangement for measuring the effective value of an a.c. signal. Said a.c. signal is applied to a first thermal convertor, while a d.c. output signal is applied to a second thermal convertor. The two thermal convertors differentially drive a differential amplifier, which at its outputs delivers the d.c. output signal. For values of the d.c. output signal which are smaller than a threshold value, a negative feedback signal which linearly depends on said d.c. output signal is applied via an additional negative-feedback network to at least one of the inputs of the differential amplifier. This facilitates zero-point adjustment, and also allows the measuring speed to be increased.

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Lelyweg, Netherlands

Hendrikus Fransiscus Bloemen