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Browse Prior Art Database

AC Current Detector Circuit

IP.com Disclosure Number: IPCOM000087447D
Original Publication Date: 1977-Jan-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 41K

Publishing Venue

IBM

Related People

Fenton, BP: AUTHOR [+2]

Abstract

The circuit detects two levels of AC current and provides two digital outputs, one indicating overcurrent and the other undercurrent. These digital outputs may be used for power supply control under fault conditions.

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AC Current Detector Circuit

The circuit detects two levels of AC current and provides two digital outputs, one indicating overcurrent and the other undercurrent. These digital outputs may be used for power supply control under fault conditions.

As shown in the circuit, the primary of a ferrite-core current transformer takes the AC current to produce a proportional secondary voltage. This voltage is rectified by CR1 and CR2, and smoothed by capacitor C producing a DC voltage across series resistors R1 and RF. A variable tap on RF feeds a reduced voltage to comparators 1 and 2.

Reference voltages for the comparators are generated by Zener diode CRT with resistor divider R4, R5 and R6. The outputs of comparators 1 and 2 are high when the AC current has its rated value and switch to low to indicate over or under AC current, respectively.

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