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    User name peter

    Log entry time 22:54:59 on June11,2002

    Entry number 85901

    keyword=Right Dipole problems

    The dipole in the right arm tripped earlier this evening (around 6pm) causing the helium level in the magnet to lower considerably. We were unable to reset it remotely and Scot Spiegel (tech-on-call) had to go into the hall to try and fix it; at the same time he was also moving the left arm into the next kinematic position.

    After looking at the right arm dipole power supply GUI, it appeared that the current set point was at 1140 A. Scot explained that the right dipole has a hardware limit of 1100 A. The trip may have been caused by the new right arm momentum setting being too high - the runplan asks for 3.2377 GeV/c for the right arm. Scot suspects that the software allowed the current in the right dipole to rise above 1100A causing the trip, even though the software should not have allowed the current to go above this limit. After Scot reset the dipole power supply in the hall (the cryogenic levels in the dipole are also back to normal), we are monitoring the current as it rises to see if the software again allows it to go above 1100A; if we see this happening we will try to set the current below 1100A and see if it stabilises the current setting. This may lead to the kinematic setting Q2_a35 being modified or postponed until this software problem can be investigated. An update will follow when we finally have the momentum and current settings for the right dipole stablised.

    Future shift workers should monitor the current in the right dipole to ensure it does not rise above 1100A and set the current appropriately should this happen.