MICE Decay Solenoid Quench Detector

Trevor HartnettDaresbury 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

Power Supply

Linear power supply

Switch mode ±15V and 12V power supply

Circuit breaker control relays

Emergency backup battery switching

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

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

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

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.

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

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

Questions?