Circuit Arrangement for Identifying and Storing Power Line Faults

1. Field of the Invention

The present invention relates to a circuit arrangement for identifying and storing power line faults, and in particular for a circuit arrangement for displaying the identity of faults.

2. Description of the Prior Art

The high expense of downtime which arrives for an outage of modern data processing systems require that the causes of such outages be detected as quickly and reliably as possible. Particularly difficult is the identification of sporadic faults as represented, for example, by inadmissibly long power line collapses, which can lead to a shut-off of the power supply and, therefore, to the outage, for example, a computer.

The object of the present invention, therefore, is to provide a circuit arrangement for identifying and storing power line faults, which faults remain displayed after the elimination of the originating causes.

The above object is achieved, according to the present invention, by a circuit arrangement which is designed such that the rectified line voltage is supplied to a comparison circuit which feeds a signal circuit, the signal circuit being connected to a memory which influences a display.

In particular, the circuit arrangement can also be designed such that the comparison circuit comprises a Wheatstone bridge having one arm comprising a Zener diode which is connected to reference voltage source, an output of the rectifier circuit connected to one diagonal of the bridge, and an operational amplifier having an input connected to the other diagonal. The store or memory comprises a bistable relay driven by a monostable flip-flop, the relay being charged with an inhibit voltage for the start-up mode. The display comprises a reset circuit and a display circuit. The bistable relay is driven via a transistor and is reset into its initial condition by way of a reset voltage. The display circuit is formed by a light-emitting diode.

As a result of the above structure, a device is provided by which power line faults can be displayed and remain stored after the shut-down of the system up to the next time the system is turned on or, respectively, despite the return of the power line input voltage.

Other objects, features and advantages of the invention, its organization, construction and operation will be best understood from the following detailed description, taken in conjunction with the accompanying drawings, on which:

FIG. 1 is a block circuit diagram for fault recognition and fault storage; and

FIG. 2 is a schematic circuit diagram of the circuit illustrated in FIG. 1.

The principles of fault recognition and fault storage are illustrated in FIG. 1.

For the purpose of power line monitoring, the rectified line input voltage U.sub.ist is compared to a reference value U.sub.soll. When the voltage U.sub.ist falls below the reference value U.sub.soll, the power line monitoring circuit emits a fault signal. This is indicated in FIG. 1 where the power line voltage U.sub.N is rectified by a rectifier 3 which feeds the rectified voltage U.sub.ist to a comparator 4 which also receives the reference voltage U.sub.soll. A fault memory 5, including a register, responds and causes display of the fault at a display 6. This alarm can be canceled by way of a reset signal RS. An inhibit signal IH serves to block the memory during run-up of the rectified power line input voltage. Moreover, this signal is also employed to inhibit the memory when the overall data processing system is turned off.

FIG. 2 illustrates a detailed circuit realization of the circuit arrangement of FIG. 1. The power line input voltage U.sub.N is rectified and smoothed via a full-wave rectifier V1 and a filter capacitor C1. The reference voltage U.sub.soll is generated via a Wheatstone bridge which comprises a plurality of resistors R1, R2, R3 and a Zener diode V2 which serves as a reference voltage source for the reference voltage U.sub.soll which is compared to the momentary actual value of the rectified power line input voltage U.sub.ist. One input (-) of the Wheatstone bridge is connected to the junction of the Zener diode V2 and the resistor R3, whereas the non-inverting input (+) of the operational amplifier is connected to the junction of the resistors R1 and R2. When the actual value falls below the reference value, then the output of the operational amplifier OP jumps from the L level to the H level. A monoflop MF is set with this edge change. In accordance with the time constants of a capacitor C3 and a resistor R6, the output of the monoflop assumes the level H and through-connects a transistor V4 during this interval, the base of the transistor V4 being connected to the output of the monoflop MF. A bistable relay BR serves as a register or memory and is connected in a collector circuit of the transistor, the relay BR comprising two windings 1, 2 which conduct the collector current so that switch contacts of the relay open. As a result thereof, a light-emitting diode V5 is extinguished the contacts of the relay lying in its energizing circuit, and the fault report is stored. When the power line input voltage is now removed, the signal IH (inhibit) must previously be applied to the monoflop MF, the information is retained. The signals RS (reset) and IH (inhibit) are externally supplied; they can also be derived from the logic of a suitable power supply. The supply voltage for the overall circuit is directly taken from the rectified power line input voltage and is generated over a resistor R4 and a further Zener diode V3, whereby the resistor R4 is connected between one corner of the rectifier bridge V1 and the cathode of the Zener diode V3, whereas the Zener diode V3 is connected between the resistor R4 and the opposite corner of the rectifier bridge V1. A filter circuit comprising a resistor R5 and a capacitor C2 is provided between the operational amplifier OP and the monoflop MF, the filter circuit causing suppression of noise pulses. A resistor R7 serves as a dropping resistor for the light-emitting diode V5 which is supplied over a DC voltage source UB given a closed relay contact. The two windings of the bistable relay BR are bridged by two diodes V6, V7 which exercise a protective effect for the transistor V5 and the drive electronics.

Although I have described my invention by way of a particular illustrative embodiment thereof, many changes and modifications of the invention may become apparent to those skilled in the art without departing from the spirit and scope of the invention. I therefore intend to include within the patent warranted hereon all such changes and modifications as may reasonably and properly be included within the scope of my contribution to the art.