Not just lost communications as from 20333. This is an SEI system. If this system has only lost communications then sure do nothing. But that state should be confirmed. If it isn't actually running then more action is call for.
At the end station, the controller computers front panel heartbeat light is not flashing. The VFD Frequency output to the motor is not changing. These two indicators convince me that the control is in fact not running. The analog pressure gauge at the pump station is reading about 78 PSI. This indicates that we got lucky and the fixed output to the VFD is pretty close to what we need to maintain the ideal pressure. About 80psi out of the pump station is nominal. Looking at the trends of the pressures and motor drive, attached, it appears they latched below the average of the normal variation. So while the pressures are trending down (only based on where the trends froze and the analog gauge,) they are doing so at a slow rate and we could be lucky and make it to Tuesday.
The IFO just dropped and Evan gave me the okay to restart. The SSH failed though so a power cycle of the computer is called for. This will certainly take down the Pump Station and therefore the SEI platforms. So we elect to wait.
If the trend had been steeper, the next indicator would have been a tripping of the HEPI as the pressures dropped too low to drive the requested offset. Meanwhile the performance of the platform would likely have become weird as the actuators were attemping to work at a pressure outside their design. Had the trend been up rather than down, if the actuators were still working at 125psi, next the in-line pressure relief valve would have opened and closed repeatedly as the pressure exceeded and dropped below the threshold. Who knows if the HEPI platform would survive this but eventually enough fluid would have been lost to the pressure relief path that the reservoir fluid trip would abruptly trip the pump station and of course the platfrom, ISI, IFO and recovery would be more painful.
