[Comm2011] Fwd: PPRS-041034-Updated-VST-CASSEGRAIN ROTATOR-Rotator Stuck, not possible to move it even by hand-Electronic
Konrad Kuijken
kuijken at strw.leidenuniv.nl
Thu Aug 29 17:43:58 CEST 2013
Begin forwarded message:
> From: Paranal_AREmail <esoarspl at eso.org>
> Subject: PPRS-041034-Updated-VST-CASSEGRAIN ROTATOR-Rotator Stuck, not possible to move it even by hand-Electronic
> Date: August 10, 2012 0:55:53 GMT+02:00
> To: kuijken at strw.leidenuniv.nl
> Reply-To: Paranal_AREmail <esoarspl at eso.org>
>
> Problem number PPRS-041034 in the Paranal PRS has now been updated.
> The new details of the ticket are listed below.
> This is for your information only.
>
>
> Problem Number : PPRS-041034
>
> Creation Date : 2011-08-04 14:09:19 by Ricardo Parra (rparra at eso.org)
> Type : Problem
> Keywords : Rotator Stuck, not possible to move it even by hand
> Priority : Critical
> Deadline :
> Status : Assigned
>
> ----- Minor Change Section ---------------------
>
> -------------------------------------------------
>
> Location : VST
> Area/Instrument Type : TELESCOPE
> System/Instrument : CASSEGRAIN ROTATOR
> Sub-system : ROTATOR
>
> Assigned to Group : Electronic
> Assigned to Person : rparra
> CC List :
> kuijken at strw.leidenuniv.nl
> par-tios at eso.org
> rtamai at eso.org
> sguniat at eso.org
> uweilenm at eso.org
> msterzik at eso.org
> vst at eso.org
> par-vst at eso.org
> akaufer at eso.org
> jspyromi at eso.org
> acarlier at eso.orgVst_all
>
> Telescope Downtime : 19:00
> Workload (hrs.) : 63
> Detailed Description :
> When investigating a possible backlash in rotator (see PPRS-041009), in the process of initializing the rotator it stopped moving near the negative end of travel, complaining of a maximum torque exceeded.
> Then we turned on the corresponding manual brake releasing key, and tried to move the rotator by hand. The rotator just moved a couple of milimeters (looking in the rotator periphery) forth and back, but nothing else.
>
> ----- Worklog & Comments Section ---------------
>
> Worklog and Comments :
> 2011-08-04 14:09:20 rparra
> For investigating in deep this problem it would be necessary to remove OmegaCAM. But for removing OmegaCAM the rotator should be at zero degrees, while at present rotator was near the limit and culdn't be moved, it was stuck.
>
> After trying many ways of getting the rotator free to move, it was found that one of the rotator motor brakes was not releasing. This was because of a bad contact somewhere in the electric feeding circuit going to the motor brake inside the rotator.
> As we don't have accesss to the rotator inside, we just tried to move the related cables in order to recover the connection and this was the case. The connection was recovered and brake released, and the rotator could move again after many hours and many people's work.
> Still pending further investigation in order to find the bad contact point and fix it, on the contrary it will happen again.
>
> This experience rises the following red flags:
> - It is necessary to improve reliability of connections, specially in zones which are quite difficult to reach, like rotator inner part, adapter, adc, etc.
> - There is no documentation. All the troubleshooting was done based just on deductions and assumptions.
> - A rotator brakes REAL STATUS is mandatory. Troubleshooting would be quite easier if we have this information.
> 2011-08-19 20:12:03 rparra
> In order to partially overcome the lack of brakes real status, today we installed reed switches detecting current presence corresponding to each of the 2 rotator brakes.
> Then LED's mounted on the brakes junction box and driven by these switches will give a visual indication of the brakes status. When the corresponding brake is consuming power the LED will illuminate.
>
> Something similar should be implemented, but instead of a led the switch must give a status signal to the VME electronics
> 2011-08-25 15:39:21 gutierrf
> This problem appeared again yesterday night, a fuse (F11, 8Amps) was found burned and the current measured in that point, was 9.0 and 9.7 Amp during the initialization. Finally, it was replaced for a new one (8Amp) and the rotator worked again. Having a copy of electrical plans, would have greatly facilitated the work.
>
> GUF/CCR
> 2011-09-09 01:28:11 vst
> This problem occured again tonight and it was impossible to fix.
> After the VST Startup, I tried to send the first Preset of the night but Rotator went to standby everytime.
> I put the system online, tried moving it from the Rotator Engineering Panel but system complained about "average torque exceeded".
> I didnt want to Initialized the device since i do not know if this could recovered so i better called E.Bugueno, he informed me that this issue is kind of known.
>
> At the end Electronic people ended up working on this problem for more than two hours, apparently one of the rotator motor brakes was not releasing.
>
> Logs showed:
>
> After sending the Preset:
> --------------------------------------------------
> 2011-09-08 23:34:16.451112 ltvadc trk trkOB2f7ac08 trkPendingCmd.c:161 64 -351131369 1 W trkERR_AXIS_CNTRL : Axis control returned with FAILURE
> 2011-09-08 23:34:16.838373 wtvst evh trkwsControl evhDB_CMD_SEND.C:866 191 -351131369 2 W evhERR_CMD_ERR_REPLY : Received an error reply to command OBJSTAR from process rottrkServer on environment ltvadc
> 2011-09-08 23:34:16.839504 wtvst prs prsControl PRESET: Command PRESET failed
> ---------------------------------------------------
>
> Trying to move rotator from Engineering Panel:
> ------------------------------------------------------
> 2011-09-09 00:02:45.281162 ltvadc axis rotPresetTask absolute preset of +0d 6m 0.0s -> target position: 0.100000(deg) timeout: 720(sec)
> 2011-09-09 00:02:56.182076 ltvadc axis rotPresetTask axisPreset.c(243) 32 8822 1 S axisERR_TIMEOUT : Timeout on reaching position
> 2011-09-09 00:02:55.889910 ltvadc rot rotServoTask disabling hardware
> 2011-09-09 00:02:56.180891 ltvadc axis rotServoTask axisServoBodyOH.c(93):"rot: Hard switch off due to handled Trigger interlock [0x 2000000] in state Servo State PosPreset"
> 2011-09-09 00:02:55.887921 ltvadc axis rotServoTask axisVelocityControl.c(169) 34 60178 1 W axisERR_ABORT : Movement aborted : maximum average torque exceeded
> -------------------------------------------------------
>
>
> Thanks all the people involved trying to find a solution,
>
> Susana.
> 2011-09-10 22:39:14 fsalgado
> Hi!
>
> Today we continued removing covers to get access to brakes and
> as soon as Matteo could touch the connector in the brake side it reacted,
>
> When the cable was taken out nothing obvious was found on it nor the connectors...
> but anyway we replaced it... (Thanks to Fernando G. and Cristian E.)
>
> so we think that there is still some possibility that the problem could be in the other connector in the brake side
> but we hope not...
>
> for the moment the rotator could go ONLINE.
>
> We left out some covers and cable trays waiting to see how it behaves next days...
> soon we will normalize it.
>
> let's cross fingers...
> Cheers!
> Fdo
> (Special thanks to Juan and Matteo for persisting to find an alternative way to reach the cable)
> Workload added: 3 people x 6 hours + 2 people x 1 hour = 20 hours
> 2011-09-12 21:57:35 vst
> The rotator was stuck again between Sept. 8 and 10, 2011, TSz
> 2011-11-27 11:29:56 rparra
> New occurence: PPRS-042849
> SYMPTOM : Rotator went to standby while tracking
> Problem Type : Electronic
> Detailed Description : Rotator went to standby while tracking with the following
> error:
> 2011-11-27 00:07:32.847871 ltvadc rot
> rotServoTask Active Interlocks: <alias>DRVOK3I
> 2011-11-27 00:07:32.849929 ltvadc rot
> rotServoTask Active Interlocks: <alias>DRVOK3I
> 2011-11-27 00:07:32.850128 ltvadc rot
> rotServoTask disabling hardware
> 2011-11-27 00:07:32.910650 ltvadc axis
> rottr2499460 axisSendRefs.c(282) 58 60178 1 W
> axisERR_TOO_LATE : New reference already in past or not enough margin:
> the delay was 150938.000000 (neg means already in the past)
> 2011-11-27 00:07:32.910890 ltvadc rot
> rottr2499460 vstrotSendRefs.c:195 23 60178 2 S
> vstrotERR_SEND_REFS : Failure from rotator from SendRefs
> 2011-11-27 00:07:33.144083 ltvadc axis
> rotServoTask axisServoBodyOH.c(93):"rot: Hard switch off due to
> handled Trigger interlock [0x 2000000] in state Servo State Pos"
> 2011-11-27 00:07:33.145035 ltvadc axis
> rotServoTask axisServoBodyI.c(72) 71 60178 1 W
> axisERR_INVALID_TRIGGERSTATE_CONT : [41]S:Servo State HwOff
> 2011-11-27 00:07:33.145470 ltvadc axis
> rotServoTask axisServoBodyI.c(72) 71 60178 2 W
> axisERR_INVALID_TRIGGERSTATE_CONT : [132]S:Servo State HwOff
> 2011-11-27 00:07:38.312434 wtvst msw
> trkwsControl Command STOP completed by @ltvaz:aztrkServer
> 2011-11-27 00:07:39.044043 wtvst msw
> trkwsControl Command STOP completed by @ltvalt:alttrkServer
>
>
> R. Parra came to fix the problem. No time lost as we still are in
> twilight
> Time Lost : 00:00
> ACTIONS : 11/27/2011 11:27:49 AM rparra
> Fuse F!! replaced.
> Closed since it is followed on pprs 41034
>
> Status Changed: Open
> Modified By: rparra
> Modified Date: 2011-11-27 11:27:49
> Status Changed: Open
> Modified By: rparra
> Modified Date: 2011-11-27 11:27:49
>
>
> __________________________________________________________________________________
> 2012-08-09 22:54:49 fsalgado
> Assignee changed: rparra
> Modified By: fsalgado
> Modified Date: 2012-08-09 22:54:49
> Assignee changed: rparra
> Modified By: fsalgado
> Modified Date: 2012-08-09 22:54:49
>
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