Basslink is set to be offline until mid-October.
The interconnector went down at 11am on Saturday.
In a statement on Monday night, Basslink said it had identified a failure in the low voltage cable which caused the interconnector's Direct Current Protection system to trip.
"The identified failure is located in an above ground section of the low voltage cable in the transition station in Gifford, Victoria," Basslink said.
"Basslink is currently preparing a plan for the repair.
"Basslink proposed further testing, which will better inform the return to service date."
The statement said the outage only affects the interconnector and Basslink's telecoms cable, which provides broadband to internet service providers, is operational.
This is the second time the cable has been out in the past three months.
Hydro Tasmania acting chief operations officer Jesse Clark said Tasmania has ample-on island resources to manage the situation.
"We have a world-class hydropower system that's served Tasmanians well for more than a century, excellent wind power resources and the ability to run gas-fired generation if required," Mr Clark said.
Mr Clark said Tasmania's hydro storages were at 45.5 per cent which is well above the high reliability level of 28 per cent.
Energy Minister Guy Barnett said Tasmania's energy position was secure as the result of the government's prudent management of water storage levels.
"Tasmanians can rely on their low cost, reliable, clean energy supply being maintained during this period thanks to our Tasmania First Energy Policy," Mr Barnett said.
Labor energy spokesman David O'Byrne said while the state's dam storages were healthy that does not mean the prolonged outage does not have an impact.
"The Basslink cable is a vital link to the national electricity market, not just for energy security, but so that we can generate income from energy sales which helps to fund essential services," Mr O'Byrne said.
"Every day this cable is out of action means lost income for Hydro Tasmania."