ACIS Users Guide -- Currents

ACIS Users Guide, Rev. A

Appendix A. ACIS Power Table

The following table lists the power consumed by ACIS due to its various components. This table was derived (stolen) from information gathered by Bob Goeke from the results of a series of Short Form and Long Form tests performed at Lincoln Laboratory (NOTE: This is taken from a note dated 19 May 1997, with some corrections from Ellen Sen on Sept. 9, 97). All the numbers shown include losses in the PSMC (order of 20% total):

**Table 17. ACIS Power Table**
State	Side-A	Side-B	A or B	Summary
PSMC Overhead	3w	3w		Total Overhead := 6w

BEP On and Running	14w	10w		Total BEP := 24w
2 FEPs On	-	-	16w
3 FEPs + 3 FEPs On	25w	25w		Total FEP := 50w
All BEPs and FEPs On (idle)				Total Static DPA := 74w

DEA 11th Board On	24w
DEA 12th Board On		18w
2 Video Boards On (idle)			7w
6 Video Boards On (idle)			21w
DEA 11th or 12th and 6 Video Boards On (idle)				Total Static DEA := 45w

Additional power with 3 + 3 FEPs processing images	1w	1w
Additional power with 6 Video Boards Clocking			8w
Total Additional Power while clocking 6 CCDs				Extra for clocks := 10w

Additional power of remaining 4 video boards are powered (idle)			15w
Focal Plane Heater Operating at Nominal Cold (-120C)			2w/6w peak
FP Heater Bakeout (30C)			52w peak
Detector Housing Heater Operating at nominal cold case (-60C)			8w/72w peak
Detector Housing Heater Bakeout (25C)			72w peak

Totals:
Normal, clocking ACIS				145w
2 CCD Calibration				90w
Standby while maintaining thermal control				54w
Memory Save Mode (no thermal control)				20w
Bakeout slewing to temperature				168w
Bakeout at stable temperature (approx.)				128w
All ACIS On (not useful, but possible)				276w

The following table indicates the total current draw by ACIS, from the perspective of the service from the spacecraft:

**Table 18. Total ACIS Current Draw**
Voltage	Current (nominal)	Current (max)*
30VDC	4.8A	9.2A
22VDC	6.6A	12.5A

* Note that 10.8A is the maximum one could draw from one service, A or B

James E. Francis

Last modified: Wed Jan 12 16:46:44 EST