REPAIR crews will spend the next week on board a specialist ship to determine the exact location of the fault in the Basslink power cable.
The underwater interconnector has been offline for more than a month, with the cause of its malfunction not yet known.
Cable vessel Ile de Re is at sea on Bass Strait de-burying the cable to try and find the fault.
Basslink chief executive Malcolm Eccles said when the ship returned to Geelong after its initial inspection more than 100 people had been working on a 24-hour operation to modify the ship ready for the repair trip.
''Over the past week, the team working on the repair of the Basslink interconnector have made good progress as we seek to repair the interconnector and return it to operation,'' Mr Eccles said.
Information Technology and Innovation Minister Michael Ferguson said data and voice traffic carried on a Basslink telecommunications cable would not be lost during the repairs.
''Tasmania currently has three cables - all of which, including the Basslink fibre, are currently fully operational,'' Mr Ferguson said.
''My advice is that providers are collaborating effectively and that services using the Basslink fibre will be migrated to the remaining two fibre bundles owned by Telstra during the period of the Basslink repair,'' he said.
Before Basslink went offline, the state was importing about 40 per cent of its power through the cable.
Hydro Tasmania's storage levels are down to 19 per cent