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Browse Prior Art Database

Secondary Circuit Protection for Highly Variable Loads

IP.com Disclosure Number: IPCOM000102750D
Original Publication Date: 1990-Jan-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 1 page(s) / 37K

Publishing Venue

IBM

Related People

Diegert, DB: AUTHOR

Abstract

Disclosed is a system to prevent fire and smoke in an electronic machine resulting form a electrical short in a DC circuit of the machine.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 100% of the total text.

Secondary Circuit Protection for Highly Variable Loads

      Disclosed is a system to prevent fire and smoke in an
electronic machine resulting form a electrical short in a DC circuit
of the machine.

      The usual protection method is to remove power when the circuit
current exceeds a preset limit.  This method cannot reliably protect
a circuit in which the power available in excess of the minimum load
requirement is sufficient to sustain combustion in a short circuit
fault.  The disclosed system will protect circuits of this type.

      The load is divided into subloads A, B, and C, such as card
assemblies.  Each current sensor a, b, and c sends a signal
proportional to its subload current to the comparator.  Current
sensor d also sends a signal proportional to the power supply current
to the comparator.

      The comparator shuts down the power supply if a, b or c exceeds
its preset current limit, indicating a short circuit in the subload.
The comparator also shuts the power supply down if d > a + b +
c, indicating a short circuit in the wiring between the power supply
and the load.

      Disclosed anonymously.