Knowledge about the condition of the cable laid in the ground and other cable systems is the prerequisite for a successful cable fault location.
Magnetic audio frequency procedures help determine the position and depth of the cable through the minimum or maximum method.
The exact location of a joint can be determined with the twist method.
Cable sheath fault location
The cable sheath is usually isolated with a PVC or PE plastic to prevent entry in the insulation. To detect possible defects early on, DC voltage sources for testing the sheath isolation and PC pulse signals for locating sheath faults are used.
Before cutting a cable, proper identification is a safety-relevant task. The computer-aided APT procedure (Amplitude – Phase – Time) developed by BAUR is the method used to identify one core from the other
with maximum safety.
The twist method patented by BAUR is used successfully in signal and multi-core cable systems. If acoustic location fails during severe short circuits and the location of joints, the audio frequency twist method makes it easy.
Voltage drop method
Voltmeter methods are used to locate sheath faults and to determine faults in light cables or low-voltage systems over the voltage drop.
Acoustic fault location
The acoustic method is used for the precise pinpointing of cable faults. The filters and runtime measurement methods that can be selected in the receiver help the user during use in the field and also enable reliable and precise location of the fault even under unfavourable ground conditions.
Decay method und differential decay method
The decay methods are used for pre-locating cable faults with high ignition voltage > 32 kV. A VLF or DC high voltage source ignites the high-resistive fault. The travelling wave recorded in the time domain reflectometer is used for measuring the fault distance.
Differential impulse current method (ICM-DIF)
With simultaneous differential measurement of two cable cores the distance can be determined even in cable faults that are difficult to find. This measurement method is applied for especially long cables, e.g. >10 km, in the T-branched network and for overhead line faults.
Impulse current method (ICM)
ICM is the classic location method for high-resistive cable faults especially in long cables.
A surge voltage generator up to 32 kV is coupled with an echometer via a current transformer. The breakdown in the fault generates current pulses that are recorded by an echometer.
Secondary Impulse Method SIM Multiple Impulse Method MIM
The SIM/MIM is the most modern and efficient measurement method for pre-locating cable faults. Particular advantages of this measurement method include easy handling, universal applicability and particularly easy interpretation of the echograms.
High-resistive faults are triggered by a surge voltage pulse at the fault, the fault distance is measured several times by the IRG echometer within a single discharge, automatically saved and displayed on the screen. The evaluation of the fault distance is performed fully automatically.
Fault burn down technology
High-resistive cable faults are handled with high performance high voltage burn down transformers. The ensuing fault becomes low resistive and therefore can be easily measured according to the TDR method. This application is used for the conventional paper-lead-sheath cables.
Time Domain Reflection Method (TDR)
The TDR method is the most established and widely used measurement method for determining the total length of the cable and the distance of cable faults and interruptions.