Browse Prior Art Database

Power Loss Detection Circuit

IP.com Disclosure Number: IPCOM000093547D
Original Publication Date: 1967-Oct-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 2 page(s) / 50K

Publishing Venue

IBM

Related People

Pawlowski, EJ: AUTHOR

Abstract

This apparatus detects a momentary loss of power or a missing line cycle to electrical equipment, typically computing devices. The apparatus also detects low voltage levels applied to such equipment or devices. The input current to the equipment or device is rectified and shaped by suitable circuit elements. The shaped wave is provided to a relay circuit. When a momentary loss of power occurs or a missing cycle appears, the relay circuit operates a failure circuit which disconnects the power supply.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 100% of the total text.

Page 1 of 2

Power Loss Detection Circuit

This apparatus detects a momentary loss of power or a missing line cycle to electrical equipment, typically computing devices. The apparatus also detects low voltage levels applied to such equipment or devices. The input current to the equipment or device is rectified and shaped by suitable circuit elements. The shaped wave is provided to a relay circuit. When a momentary loss of power occurs or a missing cycle appears, the relay circuit operates a failure circuit which disconnects the power supply.

T1, D1, D2 and D3 provide a full-wave rectifier to the AC input current. The rectified current is clipped by zener diode Z1. The clipped wave is provided to the base of transistor Q1 which in turn operates relay K1. Since the relay dropout time is 2 to 2.5 milliseconds, the circuit must provide a square wave whose offtime is less than two milliseconds. If one half cycle of the time wave is missing, the relay drops out. Also, as the line voltage drops below the clamp level of Z1, the relay drops out. Switch SW1 starts the operation by latching relay K1 through its own contacts. Once the relay has dropped out it can only be set manually. The circuit operates from 105 to 130 volts and from 45 to 100 Hertz.

The wave diagrams show the operation of the circuit at the indicated points for full operation at 60 Hertz and where a half cycle is missing.

1

Page 2 of 2

2

[This page contains 3 pictures or other non-text objects]