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Line Voltage Sense Circuitry

IP.com Disclosure Number: IPCOM000092492D
Original Publication Date: 1966-Nov-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 31K

Publishing Venue

IBM

Related People

Herman, RC: AUTHOR

Abstract

This line voltage sense circuitry reacts to a loss of power line voltage. The device is for 3-phase operation and senses the loss of all phase voltages or any individual phase voltage within one AC cycle, 16. 6 milliseconds. This allows the machine to sense an impending loss of DC power and to complete the machine operations prior to the loss of DC power. When the 18V RMS, 3-B voltage is removed from the circuit input, as is the case during a line voltage failure or machine power off sequence, the output of the device is switched from 0V DC to a +3V DC logic level. This occurs if any or all of the 3-phase lines opens and causes power off for one cycle or more. The logic level can be used to stop the computer program or shut the machine off or both.

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Line Voltage Sense Circuitry

This line voltage sense circuitry reacts to a loss of power line voltage. The device is for 3-phase operation and senses the loss of all phase voltages or any individual phase voltage within one AC cycle, 16. 6 milliseconds. This allows the machine to sense an impending loss of DC power and to complete the machine operations prior to the loss of DC power. When the 18V RMS, 3-B voltage is removed from the circuit input, as is the case during a line voltage failure or machine power off sequence, the output of the device is switched from 0V DC to a +3V DC logic level. This occurs if any or all of the 3-phase lines opens and causes power off for one cycle or more. The logic level can be used to stop the computer program or shut the machine off or both. This protects the storage contents from loss or damage due to unsequenced power down or interrogation of storage during power down.

With the input power on, a negative DC voltage, obtained from the machine primary power voltage by three And half-wave rectifiers 1, 2, and 3 and the 3- phase, Y-connected stepdown transformer 4, is applied to the base of transistor 5 by resistor 6. Transistor 5 is held in an off state as the -V DC is greater than the +V DC applied to the base by the +3V supply through resistor 7. With transistor 5 off, transistor 8 is also held in a nonconducting state due to the positive DC voltage applied to its base by resistor 9. With transistor 8 off, the output voltage i...