Philips Ambition X 1.5T: quench during second field ramp at installation
What happened
During a new site installation of a helium-free BlueSeal magnet, after warm vacuum and cooldown, a quench occurred on the second field ramp, at maximum current on the way to the set point. The third ramp completed and the system was brought to the end of commissioning.
What was checked
- Engineers performed warm vacuumisation of the helium-free magnet, then cooldown to helium temperatures with two cryocompressors running in tandem (reported as F-70 and FA-40); cold head capacity was reported around 1.25 W.
- Field ramp and shimming were started after cooldown; the quench happened on the second ramp at maximum current.
- After the quench, the team tracked re-cooling — reported roughly 2.5 days to return to helium temperatures.
- The team also reviewed the behaviour of this platform: stopping the cryocompressors on this helium-free design was reported to lead to a quench, unlike conventional helium systems.
Cause
Not determined: the quench occurred at maximum current during the second ramp, and no root cause was named in the case.
What was done
After the quench, the engineers let the magnet re-cool (reported about 2.5 days) and then performed a third field ramp, which completed successfully; shimming, settings and final tests were finished afterwards. No parts were replaced.
Safety
During any field ramp keep all personnel out of the magnet room, confirm the quench vent is routed and clear and oxygen monitoring is working, and treat the cryocompressors as critical equipment — on this helium-free design their stop was reported to trigger a quench.
Lesson: First energisation of a helium-free magnet is not a routine ramp-up: plan reserve time for quench recovery, and never break the cryo cooling chain on platforms where a stop means a quench.
Covered in the course: MRI Service — Level 2: Fault-Finding →
Written from an anonymised case shared by service engineers. It is not a manufacturer instruction and grants no authorisation. Independent note; names are trademarks of their owners.