The 20 ft. Ash Dome is equiped with slip rings to bring AC power to the
dome mounted systems (shutter, work light, flat field target). This eliminated
the need to connect a shutter control cable to operate the shutter. The
dome systems include dome rotation, shutter opening and closing, control
of the lower and upper shutter segments, and dome position and status
reporting. Particular care has been taken to design a system that protects
against the dome being left open due to AC power or computer failure.
The shutter is operated by a 1/5 HP 12 volt DC motor which is powered
by a sealed 46 Ah battery. A “smart” battery charger continuously
charges the battery without allowing overcharging. The computer system
sends “open” and close” commands by X10 control signals
over the AC wiring (connected to the dome by slip rings). In the event
of a loss of AC power (likely sign of a nearby thunder storm) or a failure
of the computer to update a “watchdog” timer, the shutter will
automatically close.
