Electricity: measuring and testing – Fault detecting in electric circuits and of electric components – For fault location
Reexamination Certificate
2001-03-29
2003-02-11
Oda, Christine K. (Department: 2858)
Electricity: measuring and testing
Fault detecting in electric circuits and of electric components
For fault location
C324S524000
Reexamination Certificate
active
06518768
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an arrangement, method and device for measuring a current in a conductor.
SUMMARY
An object of the present invention is to provide a method that is particularly simple to execute for producing a signal that characterizes a fault current in an electrical conductor that has at least three conductor ends. In this context, a fault current is understood to be a current that flows out of the conductor, or that flows into the conductor, at a fault point of the conductor, for example a short-circuit point, and thus not at one of the conductor ends.
In order to achieve this object, according to the present invention, a method is provided for producing a fault signal that characterizes a fault current of an electrical conductor that has at least three conductor ends, using current measurement devices that are arranged in such a way that one of the current measurement devices is attached at each conductor end of the conductor and the current measurement devices are connected via data lines. The method the current in the respective conductor ends is measured using the current measurement devices, and current measurement values are formed. A measurement value, formed from the current measurement values of the other current measurement devices using addition that respects the sign, is transmitted to a selected current measurement device, using the selected current measurement device, an overall current value is formed from the current measurement values thereof and the measurement value, using addition that respects the sign, and the fault signal, is produced using the selected current measurement device if the absolute value of the overall current value exceeds a predetermined threshold value. The sign-respecting addition of the current measurement values can take place in the time domain or in the frequency domain. If the method according to the present invention is used in a three-phase alternating current system, the method is executed separately for each phase, i.e. for each phase conductor; in this context, each phase can be switched off individually in the case of a fault current.
An advantage of the method according to the present invention is that it is very fast, because in the method, the current measurement values of the other current measurement devices are first combined, by sign-respecting addition, to form one measurement value, and subsequently only this measurement value is transmitted to the selected current measurement device. Since only this single measurement value need be transmitted to the selected current measurement device, the overall quantity of data to be transmitted is very small; this results in the particularly high speed of the method according to the present invention, since the smaller the amount of data to be transmitted, the less is time required for this. In addition, only a single computational step need be executed in the selected current measurement device, consisting in the addition of the transmitted measurement value to the measured current measurement value of the selected current measurement device; the transmission of the previously determined measurement value therefore relieves the selected current measurement device of further computational steps, likewise resulting in an increase in speed.
The object is also achieved by a method according to the present invention for producing a fault signal that characterizes a fault current of an electrical conductor having at least three conductor ends, using current measurement devices arranged in such a way that one of the current measurement devices is attached to each conductor end of the conductor and the current measurement devices are connected via data lines. In the method the current in the respective conductor ends is measured using the current measurement devices, with formation of current measurement values, and a measurement value, formed from the current measurement values of a first group of the remaining current measurement devices by sign-respecting addition, is transmitted to a selected current measurement device, and an additional measurement value, formed from the current measurement values of a second group of the remaining current measurement devices by sign-respecting addition, is transmitted to the selected current measurement device. The second group contains all current measurement devices except for the selected ones and the current measurement devices of the first group. Using the selected current measurement device, an overall current value is formed from the current measurement values thereof and the two measurement values through sign-respecting addition, and the fault signal is produced using the selected current measurement device if the absolute value of the overall current value exceeds a predetermined threshold value. The advantages cited in connection with the first method also hold for the second method according to the present invention. A particular advantage of the second method, is that in this method the current measurement devices can be divided into two groups and a separate measurement value can be formed for each of the two groups. This can, for example, be advantageous if the two groups of current measurement devices are separated from one another by a large spatial distance and the formation and transmission of a single measurement value to the selected current measurement device would cause a particularly high expense.
Moreover, an arrangement according to the present invention is provided with which a fault signal characterizing a fault current in an electrical conductor having at least three conductor ends can be formed in a particularly simple fashion.
This object is achieved by an arrangement for producing a fault signal that characterizes a fault current of an electrical conductor having at least three conductor ends. A current measurement device, attached to each conductor end of the conductor, measures the current in its respective conductor end with formation of a current measurement value. The current measurement devices in the arrangement are connected to one another electrically by means of data lines in a chain-type structure in such a way that each internal current measurement device in the chain is connected, with a measurement value input, to a measurement value output of the current measurement device arranged upstream therefrom, and is connected, with a measurement value output, to a measurement value input of the current measurement device arranged downstream therefrom. A first current measurement device of the two current measurement devices arranged externally in the chain is connected, with its measurement value output, to a measurement value input of the internal current measurement device arranged downstream therefrom. The second of the two external current measurement devices is connected, with a measurement value input, to the measurement value output of the internal current measurement device arranged upstream therefrom. Each internal current measurement device has an arithmetic unit that adds, in sign-respecting fashion, its current measurement value to a measurement value, present at its measurement value input, of the respective upstream current measurement device, so as to form a summation current measurement value, and outputs the summation current measurement value as a measurement value at its measurement value output. The second external current measurement device has a control unit that outputs the fault signal as soon as an overall current value, formed by sign-respecting addition from the measurement value of the upstream internal current measurement device and its current measurement value, exceeds a predetermined threshold value. An advantage of this arrangement is the particularly high speed with which the fault signal is produced, since not all the current measurement values of the other current measurement devices are transmitted individually to the second external current measurement device. Instead, only a single measurement value is transmitted that conta
Philippot Luc
Schuster Norbert
Kenyon & Kenyon
Oda Christine K.
Siemens Aktiengesellschaft
LandOfFree
Arrangement, method, and current measurement device for... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Arrangement, method, and current measurement device for..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Arrangement, method, and current measurement device for... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3150242