Most Useful Electrical Testing Equipments - Cable and Pipe Locator

Cable and Pipe Locator :-

This instrument traces underground conductive networks such as water and gas mains, telephone, cable TV, and electric power cables. It determines buried lines depth and locates underground metallic masses such as valve caps and manhole covers.
 

To locate and trace an underground metallic line, the line is energized with a radio-frequency signal generated by the transmitter and then detected by the receiver. Inductive or conductive modes of operation are available.

 

The inductive operational mode does not require direct mechanical line connection. The transmitter can energize a buried line without the need to uncover it. Just place the transmitter on the ground or pavement above the line which, once induced with the transmitted signal, retransmits the signal through the ground and air in a pattern that corresponds to its path. The line carries the signal several hundred yards depending on its depth, the mineralization and conductivity of the soil, and the transmitter power setting.

 

The conductive mode of operation requires the line to be exposed so that a direct connection can be made. Conductive energizing is preferred over inductive energizing because it results in more highly defined signal coupling. The signal generated does not spread to other conductive lines in the vicinity of the traced line. Using a ground rod with the direct connection increases the energizing efficiency and, therefore, the length of line that can be traced.

 

Two methods of receiving the transmitted signal are peak detection and null detection. The method used depends on the placement of the receiver. When held at a right angle to the surface of the ground and moved back and forth across the line to be traced, the receiver detects peaks (maximum signals) when directly above the line. When the receiver is held so its face is parallel to the surface of the ground and moved back and forth across the line, the detection of minimum signal or null (absence of signal) indicates that the line is directly below.