Performance of Optical Ground Wires During Fault Current Tests

Optical ground wires (OPGW) must be able to fulfill the regular functions of a ground wire, such as lightning protection and fault current path, as well as provide secure communications by way of the optical fibres embedded inside. Fault current tests were performed on a loose-tube design OPGW to evaluate the temperature and optical performance during and after fault current pulses, or ´hits´. Optical performance was found to be affected as early as the first rated fault current hit. Temperature Gradient tests revealed much higher than expected optical core temperatures, with resultant buffer tube damage. A temperature gradient prediction computer program was developed and independently verified the measured temperatures. A redesign of the cable will be necessary to ensure adequate optical performance for rated fault current hits.