This test has been completed. The IFO configuration has been reverted to nominal.
For future reference: yes, both the V4 and V5 hardware interlocks were found to still be connected and work. A TTL signal from the analog output port of each pump controller (TP2 and TP3) is connected to an auxiliary relay inside the main valve relay box. These serve the purpose of interupting the (Acromag) control signal to the primary V4/5 relay. This interrupt is triggered by each pump's R1 setpoint signal, which is programmed to go low when the rotation speed falls below 80% of the low-speed setting.
This afternoon Jordan is going to carry out a test of the V4 and V5 hardware interlocks. To inform the interlock improvement plan , we need to characterize exactly how these work (they pre-date the 2018 upgrade). I have provided him a sequence of steps for each test and will also be backing him up on Zoom.
We will close V1 as a precaution but there should be no other impact to the IFO. The tests are expected to take <1 hour. We will advise when they are completed.