Browse Prior Art Database

AC Power Line Monitor

IP.com Disclosure Number: IPCOM000080700D
Original Publication Date: 1974-Jan-01
Included in the Prior Art Database: 2005-Feb-27
Document File: 2 page(s) / 44K

Publishing Venue

IBM

Related People

Corchero, VA: AUTHOR [+2]

Abstract

In a three-phase AC power line, rotational direction is sensed by connecting optical isolators 10a, b c in each of the three phases of the input power line 12. The optical isolators include light-emitting diode (LED) detectors 14a, b c, respectively, and transistors 16a, b, c that are responsive to the emitted light of the LEDs. The three isolators sense phase-to-phase voltage differences. Line current phase angle is advanced in two of the phases with capacitance-reactance, to the point where the output transistors associated with the isolators provide overlapping pulses with a desired phase rotation.

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AC Power Line Monitor

In a three-phase AC power line, rotational direction is sensed by connecting optical isolators 10a, b c in each of the three phases of the input power line 12. The optical isolators include light-emitting diode (LED) detectors 14a, b c, respectively, and transistors 16a, b, c that are responsive to the emitted light of the LEDs. The three isolators sense phase-to-phase voltage differences. Line current phase angle is advanced in two of the phases with capacitance- reactance, to the point where the output transistors associated with the isolators provide overlapping pulses with a desired phase rotation.

To provide a continuous level at the output 20, the output transistors are logic OR'ed together. The outputs of the transducers produce a pulse output, if the phase rotation of the lower line is changed, or any of the three phases loses power for one or more cycles. Zener diodes 18a, b, c protect the low-reverse voltage of the isolator diodes.

By means of this sytem, whenever the rotation sequence of the power line is incorrect or when a phase is omitted, an output, which may be a display device connected to the optical isolators by way of example, will indicate such change.

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