PRE-LOCATION SCOPES : PCA301
The Adret PCA301 was developed to assist power cable fault location technicians in pre-locating and pre-determining distances to faults existing in power cables. It gives a direct reading in meters or feet to the fault position. Fault distances can also be determined from the far end of the cable by simply moving two cursors to any two points on the display screen. It is capable of locating low resistance (that is any fault lower than about 120 ohms or infinity ohms) or high resistance faults with the help of any standard impulse generator and the Adret AE101 high voltage coupling unit.
PRINCIPLES OF OPERATION
The unit is capable of pre-locating distance to fault in three distinct modes. The unit features an automatic mode in all ranges where the cable length, gain level and fault positions are indicated by the press of only a few buttons. In addition to this there is also the Expert Mode where all settings can be set by manually.
TDR, 3 Phase
In the TDR (Time domain Reflectometer) mode the instrument transmits a pulse which is reflected off the far end of the cable. Any impedance mismatches (i.e. Joints, open or short circuits) along the cable are also reflected. The waveforms are easy to analyze.
In the Impulse Current Mode a high voltage discharge generated by a surge generator is applied to a faulty cable until the fault breaks down. Thus the surge energy is then reflected back to its source. Upon arriving at the source it is reflected back into the cable. This continues until the energy is depleted. The PCA101 will capture and store the current waveform flowing in the cable and display it for analysis.
ARC-Reflection, ARC-Reflection Multi
In the ARC-Echo mode the instrument is connected to the faulty cable via the AE101 Coupling unit. This unit provides the suitable isolation and filtering required to superimpose a TDR waveform on top of the high voltage surge generated by the surge generator. When the high voltage energy arrives at the fault it temporarily breaks it down causing a short term short circuit. The waveforms are simple and easy to analyze and look exactly like TDR waveforms. ARC Reflection Multi captures and displays 15 TDR traces for easy identification of faults
Decay is used as an alternative tool when locating faults that does not break down below 32kV. The system can be used together with a DC Power source up to 60kV to assist in fault pre-location