1. MICE Decay Solenoid Quench Detector Trevor Hartnett Daresbury Laboratory

2. Outline Existing (PSI) Quench detection system – How it works – Why we want a replacement Replacement (DL) Quench detection system – Comparison with existing system – How existing system could meet other requirements Progress report – When it will be ready

3. Existing (PSI) system System overview – 3 Crates – Quench Detector – Power Supply – Battery back-up

4. Quench detection 7 Amplifier cards 7 Relay cards Latch and LED driver card Test points

5. How a quench is detected Voltage Tap Input 3 Voltage taps Resistive measurement Amplified Central tap amplified Outer voltage taps to provide reference Isolated Signal is isolated from the magnet Compared Window comparator used to compare signal Relay de-energised If signal is outside of the specified range System Latched in the quenched state Quench Triggered Relay chain open circuit Magnet Circuit breakers opened

6. Power Supply Linear power supply Switch mode ±15V and 12V power supply Circuit breaker control relays Emergency backup battery switching

7. Battery Backup 4 12V Lead acid batteries – Series connected to provide 48V – Capacity 7Ahrs Charged by a 1A, 48 V battery charger – Powered by the incoming mains. LEDs used to indicate: – Batteries charged – Mains connected

8. Recent Problems System is at least 27 years old Concern that the electronic components are approaching end of life – sticking relay – capacitor failure in the magnet PSU which is of a similar age ECS Group at DL asked to provide a Replacement QD system.

9. Replacement (DL) System Follow original principles of PSI design Update components Use a modular design Single PCB per quench channel At least existing system user interface

10. Quench detection cards Modular Design Updated components – Isolation amplifier – Relay – Latching circuit Isolation of voltage taps Test points on each card

11. Power supply 2x 230Vac to 48Vdc PSUs 2x 48Vdc to ±15Vdc PSUs 2x 48Vdc to 12Vdc PSUs Control Relays

12. Battery Backup The battery back-up crate will follow the existing design closely. A 48V, 1A charger will be used to charge four 12V batteries in series. The batteries will be 7 Ahr units.

13. Upgrades Variable voltage limits on quench detection – Voltage range from 10mV to 110mV A relay off indicator LED on each card A reset button on each card Test points are provided on each card Greater level of output diagnostics – Tripped channel can now be identified – Status indicators of each power supply Increased EMC protection to prevent nuisance trips

14. Progress Quench Detection Cards tested Power supply and battery backup still to be completed Final testing of the complete system to be carried out before the end of July Test of system with AFC in R9 at the end of July

15. Questions?