NOAA Office of Satellite and Product Operations

NOAA 12 EPS Subsystem Summary

Component Status:

Component
Description
Status
ADESolar Array Drive ElectronicsGreen
BAT 1Battery # 1Green
BAT 2Battery # 2Green
BRU 1Battery Reconditioning Unit 1Green
BRU 2Battery Reconditioning Unit 2Green
PSEPower Supply ElectronicsGreen
SASolar ArrayGreen
SADSolar Array DriveGreen
SATCUSolar Array Telemetry Commutator UnitGreen
SHUNT ASolar Array Shunt Drive AGreen
SHUNT BSolar Array Shunt Drive BGreen

Subsystem History:

Date Time Component Description
08/04/200719:45:00SAMoves array to + 80 degrees (from + 65)
08/02/200720:15:00PSEBOOST REGULATOR TO PRIMARY
08/02/200720:15:00PSEMODE CONTROLLER TO PRIMARY
08/02/200720:15:00PSERESETS PMS STATUS
08/02/200719:00:00SAMove solar array offset to +65 degrees (from -60). Caused EPS Primary Mode Controller and Boost Regulator switched from Primary to Back-up
05/23/200721:10:00SAMove solar array offset to -60 degrees (from +60).
11/28/200612:00:00SHUNT BShunt performance degraded resulting in bus voltage surges and reduced regulation of bus voltage.
09/22/200608:25:00 Sun-moon eclipse event occurred on 3 OF 4 sequential orbits between 08:25z and 14:15z. Deepest percentage of solar array occlusion was approx. 50%.
08/30/200614:20:00SAMoved solar array offset to +60 degrees (from -60) to prevent sun sensor from being shaded by the solar array while sun angle is below 20 degs because this may cause autonomous switches to YGC attitude control mode.
08/14/200612:00:00 Eclipse season ended. Spacecraft again full sunlight orbit.
06/28/200616:55:00SAMove solar array offset to -60 degrees (from +70) to reduce record high battery-1 temps.
06/09/200602:45:00SAMove solar array offset to +70 degrees (from +60)
06/08/200620:25:00SADFiltered bus voltage exceeded 28.5 so SADBIAS backed of solar array offset with 2, 8 deg steps (starting from 60 deg offset) to 76 deg offset returning back to 60 after next night-day transition. Spacecraft experiencing maximum/saturated shunt loading at this time. Array reconfiguration to reduce power generation under cconsideration.
06/06/200618:00:00SADFiltered bus voltage exceeded 28.5 so SADBIAS backed of solar array offset with 2, 8 deg steps (starting from 60 deg offset) to 76 deg offset returning back to 60 after next night-day transition. Spacecraft experiencing maximum/saturated shunt loading at this time.
06/05/200613:05:00BAT 1Battery temps exceeding 10 degs C. Command B1VT2 sent to spacecraft to change battery-1 VT curve from 4 to 2. Transmission was nominal, CV returned was nominal, VT did not change. Suspect anomolous relay or corrupt FSW bit.
06/05/200613:05:00BAT 1Battery-1 to VT level-2
05/01/200612:00:00 New eclipse season started with the first battery current discharges.
04/30/200620:55:00SADVerify SADBIAS is disabled
04/30/200620:55:00SADDisable SABIAS because it is driving the array in the wrong direction when activated.
04/30/200612:00:00 Eclipse season onset for 2006. Peaks in late-June at 20% darkness per orbit.
04/29/200618:00:00SADOverloaded shunts resulted in unregulated filtered bus voltage (above 28.5 V). SADBIAS autonomously implemented and incorrectly reduced array offset to +55 degs (from +60) instead of increasing it to +80 as was expected thus exacerbating the shunt loading problem. Problem due to change in FSW default values implemented prior to the year 2000.
03/28/200608:00:00 Sun-moon eclipse event occurred on 2 sequential orbits between 08:00z and 12:30z. Deepest percentage of solar array occlusion was approx. 50%.
10/03/200508:46:00SASolar (sun-moon) eclipse on 3 successive orbits: First and deepest eclipse was between 08:46 and 09:00Z resulting in approx. 50% loss of sun and battery discharges from 08:50 through 08:56z. No reconfigurations required, Spacecraft remained nominal throughout.
08/22/200512:00:00 N12 2005 eclipse season end.
06/23/200510:47:00SAMove solar array offset to +60 degrees (from +50). Reduces power generation and shunt stress during daylight portion of orbit.
04/21/200512:00:00 Start N12 eclipse season for 2005
04/08/200519:09:00SASolar (sun-moon) eclipse on 3 sucessive orbits: 19:09-19:25, 21:29-21:42, 23:16-23:22Z. No reconfigurations required, Spacecraft remained nominal throughout.
10/14/200400:30:00SASolar (sun-moon) eclipse intermittently for 4 hours between 00:30 and 04:30 No reconfigurations required, Spacecraft remained nominal throughout.
08/31/200415:40:00SAMoves array to +50 degree offset (from -50) while turning on tramsitters to increase load during the move then turnoff transmitters.
07/29/200417:00:00 Power subsystem back to nominal and UVTRIP threshold was lowered to 18.7 volts from 19.25. Status upgraded to Green.
07/27/200419:55:00SAChange array offset from -60 to -50 to increase power generation.
07/26/200418:40:00BAT 1 and BAT 2Reset V/T levels to 4 after on board power safe state program (STESM) set it to level 2.
07/25/200423:18:30 Battery-2 undervoltage trip (19.05 volts) placed spacecraft in power safe state mode. Electrical power load shed initiated (62 items). Subsystem declared yellow in status until recovery complete.
04/19/200412:00:00SASolar eclipse intermittently for 4 hours between 11:00 and 15:00 No reconfigurations required, Spacecraft remained nominal throughout.
11/23/200323:18:00SASolar eclipse for 19 minutes. 88% was maximum percent shading on solar array. Spacecraft remained nominal.
11/23/200321:21:00SASolar eclipse for 17 minutes. 75% was maximum percent shading on solar array. Spacecraft remained nominal.
08/27/200312:00:00 Eclipse season for 2003 ended. Spacecraft again full sun.
07/30/200313:03:00SAChange the solar array offset to -60 degrees from -45degs for shunt maintenance
07/10/200314:40:00SAChange solar array offset to -45 degrees from -30 degrees.
04/22/200300:00:00 Eclipse season started on 22 Apr 03
10/22/200213:27:00BAT 1Command battery charges to low rate charge
10/22/200213:27:00BAT 2Command battery charges to low rate charge
09/05/200215:41:00BAT 2Battery 1 and 2 to trickle rate charge
09/05/200215:41:00BAT 1Battery 1 and 2 to trickle rate charge
01/29/199800:00:00SASolar Array was changed from 55 degrees to 30 degrees to reduce shading of sun sensor.
05/15/199100:00:00SASolar Array hinge #7 telemetry readout is intermittent.
05/14/199115:26:00BAT 1On Orbit
05/14/199115:26:00ADEOn Orbit
05/14/199115:26:00SATCUOn Orbit
05/14/199115:26:00PSEOn Orbit
05/14/199115:26:00SADOn Orbit
05/14/199115:26:00SAOn Orbit
05/14/199115:26:00SHUNT BOn Orbit
05/14/199115:26:00SHUNT AOn Orbit
05/14/199115:26:00BRU 2On Orbit
05/14/199115:26:00BRU 1On Orbit
05/14/199115:26:00BAT 2On Orbit