How does ActewAGL detect underground faults?

ActewAGL have smart devices embedded within components of our network that can instantaneously detect underground fault and provide us with detailed information to determine the type of fault and or potential locality. Others may only be identified by customers calling 13 10 93. 

Once the affected area is identified, crews use maps to locate the fault and its connections to other electrical assets. This assists in isolating the cable and ensures any work done on that cable minimises risk to the public. 

We also look for issues that can cause faults, such as old joints in the cable, tight bends, locations where the cable enters or exits conduits, and where cables run near tree roots or building works. 

ActewAGL’s first priority is to the safety of the public and their employees. ActewAGL understand how inconvenient it is for customers when the power goes out so they work as quickly and safely as possible to restore power. 

ActewAGL’s fault finding equipment is in a purpose-built van. When the affected cable is identified, crews disconnect the cable from the network. A continuity test checks that both ends of the cable have been positively identified as the correct cable which needs repair.

To find the exact location, crews must first identify the type of fault. This is done with an insulation resistance test. A low resistance fault is one where there is a major breakdown in the cable’s insulation, for example damage caused from an excavator digging or a stake being driven through. High resistance faults are caused by more minor incidents, such as water seeping into old cable joints. These are much harder to locate. 

Once the fault type is identified, crews use other methods to find the exact location. For some low resistance faults, a sheath test injects an electrical signal down the cable. A technician walks the length of the cable with a sensing device to identify the point where the electrical signal leaks into the surrounding earth. 

For higher resistance faults, crews use specialist equipment to send an electrical signal down the cable that analyses the frequencies which reflect off the fault. The cable can also be surged. An amount of high electrical energy is sent down the cable. When it reaches the fault, it breaks through the insulation making a noise and a detectable magnetic field. A technician walks along the cable with amplified listening gear to locate the fault by identifying where the noise and magnetic field is. 

Once the fault is identified, associated civil works is required to expose the faulted cable and allow appropriate repairs to be carried out.