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home.web.cern.ch/about/updates/2015/03/lhc-restart-back-track

Yesterday, the teams working on the Large Hadron Collider (LHC) resolved the problem that had been delaying the restart of the accelerator. A few days ago, a short circuit to ground occurred in one of the connections between a magnet and its diode. These diodes are part of the protection system for the LHC’s superconducting magnets: they divert the current into a parallel circuit in the event of a quench, i.e. when the magnet changes from a superconducting to a conducting state.
During the training of the magnets for a beam energy of 6.5 TeV, a metal fragment became stuck in the connection, creating a short circuit to ground and preventing the diode from operating correctly. After having located the fault and carried out precise measurements, the accelerator teams decided to melt the metal fragment, in a similar way to blowing a fuse. Yesterday they injected a current of almost 400 amps into the diode circuit for just a few milliseconds, in order to make the fragment disintegrate. And it worked! Measurements made today showed that the short circuit had disappeared.

home.web.cern.ch/about/updates/2015/04/large-hadron-collider-set-restart

“We are confident of being able to restart the machine over the weekend, as all of the tests performed so far have been successful,” said Frédérick Bordry, Director for Accelerators and Technology at CERN.
When the LHC and the whole accelerator chain are running, operators work in shifts around the clock in the control room. They will attempt to circulate beams in the LHC in both directions, at their injection energy of 450 GeV, as soon as all the lights are green.
Particle collisions at an energy of 13 TeV could start as early as June.