Generator/Electricity: This morning, engineers Stan Piechocinski and Graham Mann were able to restore full power to the hab by electronic tuning of the Generac generator. The hab had been operating at reduced power from the 7kw backup gasoline generator after the Generac had unexpectedly failed last night. The Generac's engine speed is governed automatically by a circuit which monitors the altenator frequency and adjusts engine throttle by a stepper motor in order to keep it near the required mains line frequency (60Hz).

This governer circuit had been replaced recently and had apparently not been tuned properly. When started the engine would race, causing the AC frequency to rise far above allowed limits, and causing automatic shutdown. According to a data sheet from the manufacturer, the parameters controlling the behaviour of the governer - gain, stability and droop - are set by three potentiometers on the circuit board inside the front control panel (photograph will be uploaded to WebDAV separately).

The gain pot is used to stabilise the engine speed both loaded and unloaded. The droop pot is adjusted so that the engine speed settles at the preselected speed (60Hz for this unit). The stability pot sets the rate at which throttle changes are made based on the error signal from the governer. According to the manufacturer's notes, increasing stability will decrease recovery time after a disturbance, but may result in damped oscillations as the control system overshoots. Decreasing stability will soften the recovery time and reduce transients.

The optimal settings of Gain = +2 Stability =+ 1 and Droop = -1 were found by trial and error. Voltage is stable at 220v and the frequency is stable at around 60Hz with minor excursions. The system appears to be functioning normally after a full day with variable loads.

The frequency switch and stepper direction switches were left alone at the "OFF" positions (60Hz and lever set to open in the counter-clockwise position).

Propane: At 0900 hrs the tanks measured: South 50%, North - not read, Furnace - not read.

Water: Internal tank filled 2130 hrs from 3-55 gallons.

GreenHab: No progress made.

Everest Rover: Rover was prepared for multi-day EVA. 220V extension cord was removed and 2 110V plugs were wired to the Everest electrical connectors to allow compatibility with the backup Hab 7000W generator. New electrical connectors were successfully tested with generator. IRC and MOO chats were held with the Michigan rover team to go over rover use and safety procedures. ARES Rover: No progress made. Datalogger: No progress made.