MICE Decay Solenoid Quench Detector Trevor Hartnett Daresbury

MICE Decay Solenoid Quench Detector Trevor Hartnett Daresbury Laboratory

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

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

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

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

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

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

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.

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

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

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

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

Upgrades • Variable voltage limits on quench detection – Voltage range from 10 m. V to 110 m. V • • 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

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 R 9 at the end of July

Questions?