ABB's dedicated HV test van carries a variety of sophisticated equipment for the fastest possible location and repair of faults in underground cables up to 11kV
HV cable faults are inevitable, although quite rare, and are caused mainly by moisture ingress into damaged small third-party cables or cable joints. They can cause a protection device, such as a circuit breaker or switch-fuse, to operate with a consequent loss of supply.
ABB’s service team will identify the faulty circuit by EFI (earth fault indicator) operation, and switching and/or pressure testing, and restore the supply where possible. If temporary generators are needed, ABB has direct access to a supplier.
Once identified, the fault needs to be located and repaired as fast as possible. This is achieved using the dedicated ABB HV test van. Faults are generally either earth faults or open circuit faults, and can be permanent or intermittent.
Permanent faults are located using a combination of pulse echo, impulse current and capacitor discharge devices to provide a precise location. Excavation and jointing is then carried out to restore the network.
Intermittent faults can be made permanent by ‘fault burning equipment’ that uses high current, but low voltage, to accelerate the degradation. The fault can then be located as normal.