The following report has been submitted to the On-call interface.
On-call events -> Injection System
Title: ISYS main chiller failure
Author(s): chiummo
| Called at: 00:30, 04-06-2023, by: Alarm or monitoring system |
| Remote intervention: Started: 00:35, 04-06-2023; Ended: 00:45, 04-06-2023 |
| On-site intervention: Started: 01:00, 04-06-2023; Ended: 02:15, 04-06-2023 |
| Status: Action pending |
| Operator when issue resolved: None |
Details:
DMS notified that the coolant temperature of the ISYS main chiller was way above its usual value (24C instead of 19C). By looking at the evolution of the temperatures of the appliances cooled by this chiller, it was clear that very soon the neovan amplifier safety would have tripped because of temperature of diode 4 reaching 35C. This happened actually in a few minutes.
On site inspection in the EERoom found the supposedly on-duty chiller ON but with blank display. No signs of liquid leakage. Pump was still working (flow of coolant was not decreased), so it is likely that the failure concerned the heat exchange part. A quick attempt was tried to switch off and then on again and this restored the chiller display, with apparent full functionality of the chiller. Of course this chiller was not trusted, so it was switched off and then the cooling circuit was swapped to the spare chiller.
The Neovan amplifier could be switched on again, PMC relocked and so the IMC.
With the spare chiller, we have anyway reduced performances of the cooling circuit. Coolant flow was measured in around 6l/min and is now 3.8l/min. Coolant temperature was around 19C and is now 21.3C.
Both these parameters affect the working temperatures of neovan head and neovan pumping diodes. We know that Neovan head increased temperature is a source of alignment drift at the input of the PMC.
To be monitored and possibly improved on monday.
* Note that any files attached to this report are available in the On-call interface.
