A cable identifier is a specialized instrument used to identify a specific cable from a bundle of cables. In addition to serving as a standard for identification, it also acts as a criterion for judging a particular cable. It is a highly portable instrument consisting of a signal generator and a receiver.
The signal generator of the live cable identifier is powered by an AC power supply, which applies fixed-period unipolar DC pulses to the cable that has been de-energized and is to be identified. The generator output line is connected to the cable core and the grounding point or grounding pin. The cable is armored so as to be disconnected from the ground, and the core wire is connected to the remote grounding point or grounding pin. The circuit can conduct pulse current, which can be identified through the meter reading on the instrument. The current is determined by the loop resistance, which should be as small as possible.
After the transmitter and receiver start normal operation, the voltage induced in the sensor coil is displayed in the receiver head. The head pointer swings to indicate the direction of the current. Only the cable from which the current flows has its pointer swing to the right. All other cables only have current returning, and the pointer leans to the left. The output adjustment knob on the receiver can adjust the signal strength.
When using a cable identifier, to ensure the personal safety of the user, users should pay attention to the following points:
1. Before each start of the transmitter, the output adjustment knob of the transmitter should be turned to zero by turning left.
2. To ensure the safety of personnel and instruments, before starting the transmitter power, ensure that the "protective grounding post" is reliably connected to the system ground.
3. If a problem occurs with the live cable identification device, it should be repaired by professional maintenance personnel or sent back to the factory for repair to prevent the fault from expanding.
4. Some power systems are equipped with leakage protection devices at various substations. In such cases, the live cable identifier will not be able to access the cable source. To enable the cable identifier to work normally under these conditions, use a power isolation transformer or a factory-made power adapter. Alternatively, temporarily disconnect the leakage protection device and restore the leakage protection function after the cable identification work is completed.
