MICE Power Supply System John Joseph LBNL Spectrometer Solenoid Controls & Monitoring Review Dec 11 th 2012

Simplified System Block Diagram Page 2

LBNL/MICE: DC PATH [As Built] TDK/Lambda Genesys Series 500A

Energy Absorber Assemblies Energy Absorbers –Required for slow ramp down of coils –2 absorber assemblies per power supply circuit 1 EA always dissipating power into air & water

Requires 2 nd Solid State Relay –~35A of in-rush when coils energized to close contactors Replacing 15 VDC PS with 24 VDC PS –Standard for Interlock systems –Requested by RAL Potential to stagger Contactor on signal to reduce instantaneous power peak

Prestemon – Pan September 13, 2011 Spectrometer solenoid quench protection Page 6 Review of Spectrometer protection circuit

Prestemon – Pan September 13, 2011 Spectrometer solenoid quench protection Page 7 Protection circuit: test condition example Circuit with most stored energy If a quench occurs in E1: –Current shunts via diode+resistor across E1 –Coil current in E1 decays –Coil currents in neighboring coils increase Due to mutual inductance Generate bypass currents –Other coils either… Quench - very likely, due to quenchback Remain superconducting –Unlikely except for very low-current quench, when » significant margin is available »Energy in quenched coil is insufficient to boil off stored helium –Current continues to decay due to bypass resistance, but with very long time constant

Power Entry, Control, and Monitoring TB1 208 VAC 3-PHASE Power Entry TB4 Status Monitoring SSR, TB3, PS6 Interlock & Contactor Control TB2 PS Voltage Monitoring TB4 Status Monitoring K1 - V DROP K2 – V DROP K3 – V DROP K4 - V DROP K5 - V DROP K6 - V DROP K7 - V DROP K8 – V DROP CONTACT STATUS PS TEMP SENSORS

POWER SUPPLY RACK CONFIGURATION MS2 300A PS MS1 300A PS EC1 60A PS EC2 60A PS CS 500A PS EA - DA3 EA - DA4 EA - DA2 EA - DA1 K2 K1 K7 K8 K3 K6 FRONT VIEW

Prior to the next Magnet Training test… Replace the main coil power supply unit, a Power Ten 20V, 330 Amp unit, with a new TDK/Lambda Genesys series 20V, 500 Amp unit. Validate calibration information programmed into all AMI-420 Controller/Power Supply pairs –Firm requirement for the new TDK-Lambda unit Install shunts to provide alternative coil current monitoring points –Data Acquisition using Keithley scanning Digital Multimeter –Read out over RS-232 to C&M system Reconfigure the AC input power for all rack electronics to operate on 208 VAC –Lakeshore 625 end coil trimming power supplies –AMI-420 Controllers –Keithley 2700 Scanning, to operate using 208 VAC single phase Full test of trimming power supply operation into short circuit –We need to verify that the Lakeshore PS can sink up to 45 Amperes acting as a bypass for the 2 end coils that need to run at a lower operating current than the center coil. Proposed System Upgrades & Tasks