The vacuum system has been rebooted after the blackout of this Monday.
All the four pumping station are now back in operation and the vacuum level reached the 10^(-8) mbar level.
As a consequence of the blackout, all the three big gate valves along the arm were closed. After switching on the air compressor, the three gate valves opened.
Note: the penning at the South End station, tunnel side, measures 1.0e-7 TORR even if the other instrument (tower side) is deep in the 10^(-9) region. I tried to close the arm gate valve and the turbo pump gate valve on that side to check if the value was real or stuck and it seems that that penning cannot go lower than 1.0e-7 TORR.