sPHENIX discussion of the superconducting solenoid

["Schultheiss, Carl" <carls AT bnl.gov>]

Hi,

 

   On Friday we experienced two interlock events.  One at 2800 Amps

and the second at 4040 Amps.

   The first was traced to an intermittent voltage tap, VT10. This tap remained open

for a period of time after the interlock, and then reconnected.

   The second interlock was also due to VT10. The signature can be seen in all

the signals that share this voltage tap. The signals are Negative Magnet Lead,

the Inner Coil, and the Total Coil. A precursor to the event can be seen on the previous ramp.

After this event the voltage tap appeared to be connected again.

   This tap is unreliable and must be removed from the quench system.

The signals presently picked up at VT 10 will be moved to VT20. These signals are

listed above.

   The coil voltages from the inner and outer coils are compared, through a scale factor,

and are required to remain less than a threshold during ramping. To preserve the

comparison the Outer Coil signal, and the Total Coil signal will also be moved

from VT06 to VT19. This is necessary because the magnet leads develop voltages

during ramping that will now be included in the measured coil voltages. The inductances

of the coils will be adjusted by adding 8.79 mH to their previous values. This is the apparent

inductance of the leads.

   This scheme will reduce the localization of any real quenches, if they occur, but will allow

Us to continue.

 

Carl Schultheiss

Principal Electrical Engineer

Collider-Accelerator Department

Brookhaven National Laboratory