Procedure for checking the chiller load before turning on the SAGAs

  1. Ensure the S21 LCS cooling system has sufficient capacity for the SAGAs.
    1. The cooling system has sufficient capacity for the SAGA lasers if the current usage is at or below 28 kW.
    2. Open the archiver (FACETHOME→Archive Viewer) and load (File→Open) ‘S21_LCS_SAGAs_July_2021.xml’ file to load the correct PVs for the S21 LCS chiller.
    3. Click the Plot button on the middle right of the panel.

  1. The black line is the ‘chiller load’ in kW. You may have to adjust the range for chiller load using the min/max fields above the plot. The black line should be below 28 kW when the SAGAs are off.
  2. The red line (the input water temp) should be < 77° F. It is usually at 63° F or below.


Chiller system information

If the red line is below 77° F and the black line is below 33.25 kW, then the chiller system is working as intended.

The chilled water system can handle a maximum heat load of 33.25 kW. If the heat input exceeds the chiller capacity, the input water temperature will continuously climb and exceed 77° F, at which point the lasers start getting unhappy. In particular the LCLS injector lasers will get unhappy and FACET will be asked to turn the SAGA lasers off. Each SAGA requires 2.5 kW of cooling capacity, 33.25 kW - 2*2.5 kW = 28.25 kW sets the maximum load that still has capacity for the SAGA lasers.

A side note, the regen requires 1.6 kW of cooling, but, since it is typically always on, its chiller load doesn't need to be taken into account during normal operation.

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