Running on backup cooling plant

Written on January 5, 2010 – 3:00 pm | by ac45

We ran fully on internal mechanical systems last week due to a scheduled central chilled water plant shutdown.  See how ATS3’s electrical load jumped up around midnight.


What’s really strange is the correlated dip in ATS2 and jump for ATS3 on Tuesday.  The dip is about 5 kW (which we think indicates the external free cooling air being turned off) which corresponds to a 15 kW increase in load on the compressors.  Makes sense but we need to understand what prompted the external cold air fans to be turned off — maybe it got too cold?  The control systems are not linked among the CRACS and AHUs.

The following three graphs are the IT load, variously on ATS4 and PP26&27: