Apparatus for monitoring the status of devices in electrical protection and control systems
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United States of America Patent
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-
Feb 25, 2003
Grant Date -
Oct 4, 2001
app pub date -
Jan 30, 2001
filing date -
Feb 1, 2000
priority date (Note) -
Expired
status (Latency Note)
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Abstract
A protection and control system incorporates status acquisition apparatus for use in monitoring the status of a device in the protection and control system, such as a protection relay in a high voltage electrical circuit. The status acquisition apparatus comprises a conversion circuit which converts an input voltage to a pulse width modulated signal and a comparison circuit which monitors the pulse width modulated signal to determine the status of the device. The mark-space ratio of the pulse width modulated signal decreases as the input voltage is increased to minimize power dissipation over a range of input voltages. The status acquisition apparatus may form an integral part of a protective switching device, although other applications are envisaged.
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