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\large
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\centerline {\bf 3.2\_V2.0 EMERGENCY LOAD SHED PROCEDURE } 
\vspace{0.25in}

\normalsize
\noindent{\it Last Revised: June 28,1999}\\
\noindent{\bf Filename: SILSSCS} \\

\noindent {\bf BRIEF FUNCTIONAL DESCRIPTION:} \\
\normalsize
This procedure is to turn the ACIS instrument off within $\sim62$~s in
the case of a spacecraft power emergency. The procedure is intended to
work for any ACIS configuration and thus sends commands to the A and B
sides without checking if they are actually on. 
The procedure first interrupts the current
science run then turns off the DH bakeout heater (which may or may not
be on), turns off the DH heater, powers off the DEA video boards,
FEPs, DEA power supply and DPA power supply, while allowing enough
time to get the interesting telemetry out of the instrument.  At the
end of the procedure, the ACIS power consumption should be 6~W 
(the parasitic load of the PSMC).
All the commands have been doubled to be consistent with the general
paranoid hysteria.


\vspace{0.25in}
\noindent The sequence of actions will be: 
\be
\item interrupt the current science run
\vspace{-0.10in}
\item turn off and disable the Detector Housing bakeout heater
\vspace{-0.10in}
\item turn off and disable the Detector Housing heater
\vspace{-0.10in}
\item turn off and disable the Focal Plane bakeout heater
\vspace{-0.10in}
\item turn off the DEA video boards
\vspace{-0.10in}
\item turn off the FEPs
\vspace{-0.10in}
\item Turn off the DEA 
\vspace{-0.10in}
\item Turn off the DPA
\vspace{-0.10in}
\item Verify that ACIS is off by checking input currents and voltages
\ee


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\normalsize
\noindent {\bf ASSUMED INSTRUMENT STATE:} \\
\normalsize
None, procedure is intended to work for any ACIS configuration. \\

\vspace{0.25in}
\normalsize
\noindent {\bf SPECIAL INITIAL CONDITIONS:} \\
\normalsize


%\newpage 

\vspace{0.25in}
\normalsize
\noindent {\bf OPERATIONAL CONSTRAINTS/CAUTIONS:} \\
\normalsize
This procedure leaves ACIS completely off; therefore there is no
active thermal control.\\
The SW TLM verifiers are only available if the spacecraft is in FMT 1
or 2.


\vspace{0.15in}
\normalsize
\noindent {\bf REFERENCES:} \\
\normalsize

\normalsize
\noindent {\bf CHANGE HISTORY:} \\
\normalsize

{\bf V1.3}
\begin{itemize}
\item added SW TLM verifiers throughout the procedure
\item fixed typos in steps 3.7 and 3.8
\item added step 9 to confirm that ACIS is indeed off
\end{itemize}

{\bf V2.0}
\begin{itemize}
\item ACIS Team signed-off version
\item changed version number in ``Change History'' to 1.3 from 1.2
\item changed HW TLM verifier in step 9.3 to ``1DEN1AVO''
\item changed HW TLM verifier in step 9.4 to ``1DEN1BVO''
\end{itemize}

\newcommand{\tablecaptiontext}{ACIS Emergency Power-Down Procedure}
\input{SILSSCS.tab}

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