Документ взят из кэша поисковой машины. Адрес оригинального документа : http://www.stsci.edu/smov/NICMOS_NCS/STIS%20MAMA%20NCS%20mgmt%20%2020mar01.doc Дата изменения: Thu Jun 21 00:26:49 2001 Дата индексирования: Sat Mar 1 07:27:24 2014 Кодировка:

Recommendation for the operation of the STIS MAMAs during NCS initial turn-
on and cool down:

It is recommended not to turn on the STIS MAMAs until after 100 hours after
the NCS initial turn-on, assuming that the valve heaters are shown to be
cycling properly and controlling the value temperatures above their leak
level. This recommendation may change depending on the final assessment
from the CHAMPS Thermal group of the following risk periods. This final
assessment is dependent upon the NCC portion of the model finalized. The
Thermal group expects this work to be completed by the end of April.

There are three times of high risk times for turning on the high voltage on
the MAMAs due to potential leaks from the NCS during initial turn-on and
cool down:

Risk #1: There is a risk of a potential leak during the initial fill of
the NCC. The initial fill will be done prior to the first maximum cool-
down.
a. The initial fill will be done via the command plan, and the
instruments will be safed during this time. Since STIS will be
safed during this time period this is a non-issue for managing
the MAMA high voltage.

Risk #2: Preliminary thermal assessment shows the first 10 hours of NCC
operation as the greatest rate of temperature change for the cool down of
the values and bayonets.
a. Recommendation is to wait until approximately 48 hours after the
inlet value and bayonet have stabilized (~10 hours after initial
cool down). During the first 48 hours, the system is reaching
equilibrium and a possible leak could occur.

Risk #3: Another risk period for a potential leak could occur as the NCC
begins its cool down before the valve heaters are shown to be cycling
properly and controlling the value temperature above their leak level.
Preliminary thermal assessment show that the valves settle into their
cycling in approximately 100 hours.