File $Source: /home/juda/www/hrc_flight/RCS/failsafe_negy.html,v $
Version $Revision: 1.3 $
Last Update $Date: 1999/05/10 18:08:08 $
HRC CCB Status Approved

OP03 Procedures op03:

HRC Contingency Command Sequences

Fire -Y Shutter Failsafe

Description:

This sequence operates the -Y shutter failsafe. First, the Failsafe Master Relay, cal source, +Y shutter, and -Y shutter relays are disabled. The master relay is enabled, the configuration is verified, and then the -Y shutter failsafe relay is enabled. After verifying the failsafe actuation, the master, cal source, +Y, and -Y shutter relays are disabled.

Cautions/Restrictions:

This sequence must only be used as a last resort; once the failsafe has been executed the -Y shutter can no longer be used.

Flow Diagram

Delta-Time Command Mnemonic Description Cmd Field Mnemonic Data Parameter Telemetry Verifier Expected Value Notes
00:00:01.000 2FSMRDI Disable Failsafe Master Relay     2FSMRST DISA hlp24
00:00:01.000 2FSCSDI Disable Failsafe Cal Source Relay     2FSCAST DISA hlp28
00:00:01.000 2FSPYDI Disable Failsafe +Y Shutter     2FSPYST DISA hlp66
00:00:01.000 2FSNYDI Disable Failsafe -Y Shutter     2FSNYST DISA hlp6a
00:00:01.000 2FSMREN Enable Failsafe Master Relay     2FSMRST ENAB hlp22
Verify proper failsafe configuration
00:00:01.000 2FSNYEN Enable Failsafe -Y Shutter     2FSNYST ENAB hlp69
Wait for -Y shutter failsafe actuation
00:00:01.000 2FSNYDI Disable Failsafe -Y Shutter     2FSNYST DISA hlp6a
00:00:01.000 2FSCSDI Disable Failsafe Cal Source Relay     2FSCAST DISA hlp28
00:00:01.000 2FSPYDI Disable Failsafe +Y Shutter     2FSPYST DISA hlp66
00:00:01.000 2FSMRDI Disable Failsafe Master Relay     2FSMRST DISA hlp24

$Log: failsafe_negy.html,v $

Revision 1.3 1999/05/10 18:08:08 jhc

corrected initial time delay to 1 sec

Revision 1.2 1999/04/07 18:42:27 juda

HTML changes: added "name" tags to sub-sequences

Revision 1.1 1999/03/03 20:09:10 juda

Initial revision

Revision 1.2 1998/11/16 21:19:50 juda

removed commands to turn off the power bus - changed order of enables of failsafes (master first then -Y shutter after a verification)

marked as approved

Revision 1.1 1998/11/03 21:11:02 juda

Initial revision

Dr. Michael Juda
Harvard-Smithsonian Center for Astrophysics
60 Garden Street, Mail Stop 70
Cambridge, MA 02138, USA
Ph.: (617) 495-7062
Fax: (617) 495-7356
E-mail: mjuda@cfa.harvard.edu