Seba Dynatronic Mess-und Ortungstechnik Gmbh

Metrotech Corporation

Hagenuk Kmt Kabelmesstechnik Gmbh

Hubert Schlapp

Johan D Overby

Patrick Gray

Frieder Jehring

Richard Allin

A voltage pulse is transmitted into a test object, and returned reflection pulses are evaluated to determine the location of a fault in the test object. The return signal includes a reflection from the fault and undesired interfering reflection pulses, which are removed or compensated-out from the return signal to produce a corrected pulse diagram. A circuit arrangement for this includes a bi-directional coupler, a separation filter, a measured signal detection circuit with two input channels, a memory storing a database, a computer processor, and a measured signal evaluation unit. A method in this regard includes a first step of measuring the input impedance of the test object, and a second step of measuring the return signal pulses, transforming the return signal to the frequency domain, compensating the frequency domain data to remove interference, transforming the data back to the time domain, and representing or evaluating the pulse diagram.

Method and apparatus for locating a fault in an electrical conductor, with interference compensation

The invention relates to a method for error location in branched low voltage and medium voltage networks and to an evaluation network used therefor. The inventive method consists of the following steps: initially, the frequency of the low-frequency component of the impulse wave current or voltage is determined; the circuit inductance is calculated, using a Thomson resonant circuit formula, from the determined low-frequency transient frequency with the known capacitance of the impulse capacitor; the inductance of the impulse capacitor and the measuring line is deducted as a correction factor; finally the distance from the place of error in the cable is calculated from the inductance thus calculated on the basis of the inductance of the measured object, the advantage thereof being that it is possible to located voltage-dependent cable errors in a branched low-voltage or medium voltage network by means of length determination in a quick and error-free manner without signal reflections causing disturbances on branches or end points of the cable. The evaluation circuit is provided with a conditioning and protection component, an A/D converter and at least one memory unit, in addition to an evaluation computer for the signal.

Method and error location in branched low voltage and medium voltage networks and evaluation circuit used thereof

When cables run side by side over a longer distance, an alternating-current signal used for cable location can couple or 'bleedover' to neighboring cables. The coupled current flowing in the neighboring cable creates field distortion and makes position determination of the targeted cable difficult. The resulting magnetic field of both (or more) cables has a non-circular shape and is commonly known as a distorted field. Established methods for finding the position of the cable under investigation lead to inaccuracies or even wrong locates. The method described herein eliminates the field distortion that is due to the coupled cables by demodulating a phase reference signal placed on the cable by a transmitter into two signal strength constituents. The inphase signal represents the field strength of the targeted conductor and is substantially free of field distortion. The other quadrature signal contains the component of the field associated with distortion.

Method for decoupling interference due to bleedover in metallic pipe and cable locators

A procedure and a system for the detection of a plurality of passive electronic markers are disclosed. A marker location device capable of scanning for multiple types of electronic marker thereby increasing operator efficiency and reducing erroneous marker indications is described. In some embodiments, scanning may be performed at the operating technician's direction or may be performed in the background while the operating technician is performing other tasks.

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Ebern, Germany

Hubert Schlapp