gregorian amp 32 failure nov13
Noises were reported coming from the
gregorian dome speaker (in the control room) on 25nov13. A visual
inspection found nothing out of the ordinary.
The dome motor torques for the month of november
were inspected. Motor 32 looks like it has been having problems
Some of these failures can be seen on the plots of the dome motor torques for
part of 26nov13 (.ps) (.pdf):
- plots are made of .2 hour sections (12 minutes)
- For each section there are 2 frames.
- The top frame of the pair shows the za vs time
- the 2nd frame of the pair shows the torques vs time for the
- Each motor in color coded.
- Page 1:
- 0 to .2 hours
- the dome was moving from 14 to 16.5 deg za.
- The dark red trace is motor 32 torque.
- HB means that a hydraulic brake is connected to this motor
- .2 to .4 hours
- mot32 was dropping out until .25 hours.
- At .25 hours the domed stopped moving.
- The torque from mot32 went to 0
- At .29 hours the dome started moving uphill fast.
- The mot32 torque was output ok
- At .3 hours the za rate slowed down, the torques started
- At .315 hours the dome started downhill
- moving downhill, there are no jumps (in this za range)
- At .375 hours, the dome started uphill again , mot32
started dropping out again
- Page 2:
- .4 to .6 hours
- Dome moved down and the up (must have been close to
- Moving downhill, there are no dropouts. Moving uphill
there are. this was repeatable.
- 2.65 to 2.85 hours
- at 2.69 th motors were turned on.
- no torque from mot32 while dome sits still
- At 2.75 start moving uphill at a fast rate. No mot32
- Page 3:
- 4.40 to 4.60
- mot32 torque starts oscillating when turnaround
approached (at 4.5 hours)
- when starting back up, dropouts start.
- 4.6 to 4.8
- moving uphill at a slow rate, mot32 had little torque with
- rapid uphill motion had more normal torque output for motor 32
- moving downhill had normal torque until the velocity
approached 0. The torque then began to oscillate
- When sitting still, the torque would go to 0 (rather than sit
and the normal holding torque).
- Looking at previous days, this problem with motor 32 has been
occurring since 12nov13.
- on 26nov13 around 14:00 the amplifier for motor 32 was
- The motor has performed normally (at least for the 3 hours
since the replacement).
- We should not have run for 2
weeks with the amplifier malfunctioning...
- We need to display the torque vs time in the control room
(both dome and azimuth)
- The programs to do this exist, we just need some video
monitors to display them on.