- carried out weekly checks for boiler, AHU and chillers in TB, CEB and MC
- refill of the LPG tank in Central area from 8.30 to 8.45 (UTC)
- carried out periodic check for AHU fan-motor belts state of tension and consunption (with external firm) with a short shut down of the involved machines:
AHU Clean rooms CEB: off at 6.40 - on 7.25 (UTC) ---> status OK
AHU INJ: off at 7.30 - on at 7.45 (UTC) ---> status OK
AHU DET: off at 8.53 - on at 9.08 (UTC) ---> status OK
- carried out weekly visual checks for boiler, AHU and chillers in TB and CEB
- refill of the LPG tank in Central area from 9.30 to 9.50 (UTC)
- carried out periodic check for AHU fan-motor belts state of tension and consunption (with external firm) with a short shut down of the involved machines:
AHU NEB: off at 6.47 - on 7.00 (UTC) ---> status OK
AHU WEB: off at 7.09 - on at 7.30 (UTC) ---> status OK
AHU CEB Hall: off at 7.50 - on at 8.05 (UTC) ---> status OK
AHU MC: off at 8.12-on at 8.26 ---> status OK
- Replacement of servo controls for the pre-heating and post-heating coils for the AHU DET Lab: task started at 6,30 (UTC); unfortunately, during this task, the 24 V transformer for the electrical power supply of the servocontrols inside the electrical cabinet was damaged; and it was necessary to replace it with a temporary one; this fault led to the restoration of operation of the air conditioning system at 5.30 pm (UTC), well beyond the maintenance limit.
Many Thanks to Massimo D'Andrea for providing the replacement quickly.
The new transformer will be available today and its installation, which requires a downtime of approximately 30 minutes, will be agreed based on the activity of the interferometer.
- carried out weekly visual checks for boiler, AHU in CEB, TB and MC;
- carried out weekly visual checks for boiler, AHU in NEB and WEB;
- refill of the LPG tank in Central area from 7,00 to 7,30 (UTC);
- repalcement of the broken air speed sensor for FC_EB clean room (AHU off from 8,50 to 9,00 UTC)
- carried out weekly visual checks for boiler, AHU in CEB, TB and MC;
- carried out weekly visual checks for boiler, AHU in NEB and WEB;
- refill of the LPG tank in Central area from 8,00 to 8,30 (UTC);
- installation of the dryer for air compressor n. 1(sx) in TB after maintenance in external mechanical workshop;
- check for 1500 West clean room AHU: replacement of servo controls for three-way valves necessary --> supply time 1 week
- carried out weekly visual checks for boiler, AHU in CEB, TB and MC with additional controls for drainage pumps in AHU CEB room (floating-switc regulation)
- carried out weekly visual checks for boiler, AHU in NEB and WEB
- refill of the LPG tank in Central area from 7,00 to 7,30 (UTC)
- carried out weekly visual checks for boiler, AHU in CEB, TB and MC
- refill of the LPG tank in Central area from 8,30 to 8,50 (UTC)
- carried out periodic maintenance work (with external firm) for steam producers for the AHUs of INJ, DET, FCIM and FCEM starting from 8,00 to 11,15 (UTC)
No activities in NEB and WEB
- carried out weekly visual checks for boiler, AHU in CEB, NEB, WEB and MC
- refill of the LPG tank in Central area from 10,15 to 10,30
- carried out periodic maintenance work (with external firm) for all the chillers on the site, including those dedicated to the systems for the experimental halls and laboratories; for the TB (for CEB and INJ and DET plants), NEB, WEB and MC buildings, since for redundancy reasons the chillers in question are all double, it was possible to carry out maintenance without interrupting the production of chilled water, by turning off one at a time.
However, the actual duration of the maintenance was from 8.30am to 1pm
- carried out weekly visual checks for boiler, AHU and chillers in TB and CEB
- refill of the LPG tank in Central area from 11,45 to 12,00
- carried out periodic check for AHU fan-motor belts state of tension and consunption (with external firm) with a short shut down of the involved machines:
AHU MC: off at 9.00-on at 9,15 ---> status OK
AHU CEB Hall: off at 9,21 - on at 9,28 ---> status OK
AHU CEB Clean rooms: off at 9,30 - on at 9,40 ---> status OK
AHU WEB: off at 9,46 - on at 9,55 ---> status OK
AHU NEB: off at 10,07 - on 10,15 ---> status OK
This morning the fancoil n1 get stuck and the temperature in the DAQ increased quickly (picture attached). I restarted successfully it at 7:55 LT and we informed the external firm in order to do further checks. Moreover I decreased the temperature of intervention of the third fancoil used as backup in order to prevent this kind of events.
these the time of shut down for each unit:
AHU Inj Lab: off 9,41 - on 10,12 (local time)
AHU Det Lab: off 10,25 - on 10,47 (local time)
All filters inside machine has been replaced; internal cleaning and sanitization; functionality control of internal shutters and their actuators; check correct seal between motor and fan
At WEB, also the cleaning of the Y-filter for post-heating coil was carried out; no time enough for same operation at NEB.
These the downtime per AHU (in local time):
CEB Hall AHU: off @8.33 - on @9.27
WEB Hall AHU: off @9.48 - on @11.15
NEB Hall AHU: off @ 11.45 - on @12.17
More precisely, the operating logic was not respected by the servocontrol which was positioned at maximum opening, causing the temperature in the laboratory to increase.
The effects of the replacement are yet to be verified in the operation of the conditioning system in the next few hours.
In order to reduce also NEB-AHU COLD loop oscillations, especialy associated with low temperature chiller regime, (according to WEB AHU PID Controller tuning), on September 13th, we modified the NEB-AHU PID Controller parameters, in detail:
14:35 UTC removed derivative term (from 90 sec to 0 sec) and increased proportional band from 3 to 4.
Fig.1 and Fig.2 summarizes consequences of our actions.
The removal of derivative term stops the oscillation (period 120sec). The residual oscillation in the correction signal, follows the chiller temperature (Fig2).
The reintroductiion of derivative term, 90 sec, on Sep 18th 8:30 UTC , in contrast with WEB, causes again loop instabilities (Fig3, Fig.4).
The derivative term has been removed on Sep 19th 13:58 UTC (Fig.5).
PID parameters:
Integration time: 360 sec
Derivative time 0 sec
Proportional band 4°
In order to reduce oscillations of WEB-AHU COLD loop, on September 4th, we modified the WEB-AHU PID Controller parameters, in detail:
9:11 UTC removed derivative term (from 90 sec to 0 sec)
11:45 UTC increased proportional band from 3 to 4
14:25 UTC increased derivative time fro 0 to 90 sec.
Fig.1 summarizes consequences of our actions.
In details, the removal of derivative term stops the oscillation (period 120sec). The residual oscillation in the correction signal, follows the chiller temperature (Fig2).
The reintroductiion of derivative term causes a further reduction of the temperature error signal (Fig1).
PID parameters:
Integration time: 360 sec
Derivative time 90 sec
Proportional band 4°
Temperature in the WEB hall dropped to 0,7 degree below the set point (22,5 C).
This morning at 8.20 (L.T.) I restored operation and the temperature of the cold lop returned to set (14 degrees) in 30 minutes.
At same time, to try to obtain a more rapid drop in room temperature, I have temporarily decreased the cold loop setting to 12 degrees.
At 9.40 (L.T.) the room temperature in the hall ("hot" loop) returned to its set point (21.5 degrees), and I gradually return the temperature of the cold loop to its previous set (14 degrees)
This is the list of the actions performed:
- thermal insulation of the room door (fig1)
- thermal insulation of the trapdoor (fig2)
- sealing of the passage holes for cables and pipes (figs 3-4-5)
- thermal insulation of the chiller pipe fittings (figs 6-7)
- moving the room temperature sensor to a position less subject to the fancoil air flow, and closer to the fancoil in-loop sensor (fig8). This is to have a better monitoring of the room temperature. The jump of about 1 degree in the temperature signal (fig9) is due to the new position of the sensor. No change in the set-point of the control loop.
Other actions may be done in the future, but to be agreed in advance with the TCS subsystem coordinator.
His set point is 22 C, in cooling only mode, the position of the deflector fins has been blocked so that the fresh air is directed towards the chillers.
The remote control is contained in its case on the wall facing the entrance but please do not modify the current sets arbitrarily.
The air conditioner has the "auto-restart" function so in the event of a blackout, when restarted it maintains the settings given.
