# Presentation: 157391

## Section 16

_***Section 16***_
***Electrical***

*** ******. . . Bruce Zink***
*EO-1 Electrical Lead, Swales Aerospace, Inc.*

## Contents

***Contents***

***System Block Diagram***
***Verification Matrix***
***Failure Free Time***
***Changes since last review***
***Remaining Work to be Performed***
***Critical RFAs***
***Status of Open Actions***
***Residual Risk***
***Launch Readiness***

## System Block Diagram

## Power System Block Diagram

## “As Run” Verification Matrix

## Projected Power On Time

## Changes Since Red Team Review

***Changes Since Red Team Review***

***WARP re-integration***
***Following WARP repair and test***
***Calorimeter integration and verification***
***ACDS removal, rework, and re-integration***
***Interpoint converter stiffener installation***
***GPS Power Converter Unit removal, rework, and re-integration***
***Interpoint converter stiffener installation***
***AST removal, rework, and re-integration***
***Interpoint converter stiffener installation***

## Changes Since Red Team Review (continued)

***Changes Since Red Team Review ****(continued)*

***IRU re-integration***
***Following removal to prevent Helium exposure***
***1773 Bus Characterization***
***Verify bus performance following breaking connections to ACDS, WARP, Hyperion, and AST***
***Minimum system margin >9dB over temperature range***
***Trickle Charge Diode Installation***
***Replaced fuse with diode and tested successfully***
***S-Band Transponder Removal***
***Returned to manufacturer due to AGC oscillations***
***Integrated command uplink bypass to continue powered testing***

## Remaining Work To Be Completed

***Remaining Work To Be Completed***

***Harness Closeouts***
***Remaining work related to re-installation of S-Band transponder and bay closeouts for flight.***
***S-Band Transponder Repair***
***S-Band Transponder Re-Integration***
***Repeat of previous successful integration following repair***
***Hyperion Re-Integration***
***Repeat of previous successful integration following removal to allow integration of S-Band Transponder***

## Remaining Work To Be Completed (continued)

***Remaining Work To Be Completed ****(continued)*

***S/A Integration***
***Repeat of previous successful integration for Vibration & Acoustic Test***
***1773 Bus Characterization (following Hyperion final integration)***
***Required due to Hyperion de-mate***
***Repeat of previous successful integrations***
*Performed 7 times to date*

## Status of Open Actions

***Status of Open Actions***

***1773 Bus Fault During MOC Sim (WOA 876 PR20-1, 20-3)                                          ***
***Modification of PSE “default” power on configuration mitigated problem***
*PSE SW Build 8.1 performs load shed of all non-essential loads following special command reset*
***Solar Array Deployment Test***
***All testing to date successful***
***Planned for launch site***
*Primary side with flight fuse plug*

## Residual Risk“One Time Events” (Redbook Items)

***Residual Risk****“One Time Events” (Redbook Items)*

***Chassis current Transient (WOA #770-20-3,  PR20-3)***
***One event of ~300mA, also seen on stripchart recorder***
***EMC testing was taking place with probes connected to spacecraft power bus***
***No recurrence since event on 11/22/99***
*1390 Hours of powered testing*
***Chassis current event (WOA #572-30-10)***
***Prolonged chassis current event reaching a peak of 925 mA***
***Ad Hoc testing immediately following event caused brief recurrence of anomaly***
***Solar Array Simulator cable (EGSE) found to have split insulation on multiple wires within backshell***
***Following inspection a new Solar Array Simulator cable was fabricated***
***No recurrence since 8/20/99 ( with exception of 770-20-3 which was a brief event )***
*2370 Hours of powered testing*

**16 - **

## Residual Risk(continued)

***Residual Risk****(continued)*

***1773 Bus Fault during MOC Sim (WOA 876-20-1 and 876-20-3, PR20-1, 20-3)***
***1773 bus susceptible to “babbling” transmitter***
*Low risk of fault (TRMM and XTE heritage)*
***Change in PSE “default” services mitigated risk associated with this problem (Version 8.1)***
*Special command reset sheds all non-essential loads*
***Operational ability to re-set or power down all non-essential RT’s***
*Ability to remove babbling RT, or re-set and stop babbling*
***Low likelihood of occurrence combined with operational workarounds results in low risk associated with this issue***
***S-Band Transponder Anomaly***
***AGC oscillations must be diagnosed and repaired***
***See Special Topic***

## Launch Readiness

***Launch Readiness***

***Complete troubleshooting of S-Band Transponder***
***Locate problem***
***Fix problem***
***Integrate and Test S-Band Transponder***
***Repaired unit***
***Complete system level testing (CPT, S/A deployment)***
***Previous success suggests low risk***
***Complete remaining activities ***
***See previous section on Remaining Work to be Completed***
***Low risk S/C closeouts and repeats of previous integrations***
***Ready for launch following previously mentioned activities***

## Special Topic Follow-Up:

***Nadir Deck Heater Short***

*** ******. . . Bruce Zink***
*EO-1 Electrical Lead, Swales Aerospace, Inc.*

## Nadir Deck Short Circuit

***Nadir Deck Short Circuit***

***Summary of Event (WOA 676-20-8)***
***Mis-wired heaters caused high current events in first TVAC***
***Repair Implementation***
***Heater circuits and switched services in question abandoned***
***New heaters installed on nadir deck***
***Re-wiring performed to re-establish lost services***
***Test and Verification***
***Circuits tested by jumpering thermostats***
***Circuits verified in T/V II cold plateau***
***Negligible residual risk***

## Special Topic:

***Umbilical Console Operational Issues***

*** ******. . . Bruce Zink***
*EO-1 Electrical Lead, Swales Aerospace, Inc.*

## Description of Problem

***Description of Problem***

***GPIB bus internal to Umbilical Console suffers from periodic “crashes”***
***Conflict on bus (cause not fully understood) results in loss of commanding and status telemetry from solar array simulators and Direct Power Converter supply***
***Existing configuration of supplies remains following a “crash”***
***Commanding of output relays for the solar array simulators and DPC is not affected by GPIB “crash”***
***Communications with ASIST is not affected by a “crash”***
***Does this situation create risk associated with Launch??***

## Umbilical Console Block Diagram

- Windows NT Computer

- HP Solar Array Simulator

- Sorenson DPC/Master

- Sorenson SAS 3

- Sorenson SAS 10

- GPIB
- Bus

- Sorenson
- Bus

- Switch
- Control

***ASIST used to command UC and acquire telemetry***
***GPIB Bus used to control settings on power supplies***
***Sorenson Bus mimics GPIB bus for remaining supplies***
***Output relays controlled via dedicated hardware not on GPIB bus***

- To Spacecraft

- Ethernet ASIST Link

## Umbilical Command Timeline

***Umbilical Command Timeline***

***Power up***
******Configure DPC to +30V***
***Close DPC output relay***
***Bring S/C Battery On-Line***
******Adjust DPC to match battery voltage***
***Send battery on pulse***
***Open DPC output relay***
******Adjust DPC voltage to 22VDC***
***Configure Solar Array Simulators***
******Adjust HP SAS and all Sorenson supplies to standard settings***

- *** Denotes use of GPIB Bus

## Umbilical Command Timeline

***Umbilical Command Timeline***

***Standard Spacecraft Operations***
***Cycle SAS output relays to control battery charging***
***Launch (T-5 minutes)***
***Open all SAS output relays to go to internal power***
***Scrub/Power Down Spacecraft***
******Adjust DPC to match battery voltage (iterative process)***
***Close DPC output relay***
***Issue battery off pulse***
***Open DPC output relay***

- *** Denotes use of GPIB Bus

## Umbilical Recovery Procedure

***Umbilical Recovery Procedure***

***Wait for spacecraft “night”***
***SAS supplies reconfigured during recovery, no effect on spacecraft when SAS output relays are open***
***Exit Umbilical SW program***
***Performed using remote administration from remotely located computer***
***Cycle AC power to Sorenson DPC supply***
***Performed using remote controlled power switch***
***Controlled via fiber link from remote PC***
***Re-start Umbilical SW program***
***Performed using remote administration from remotely located computer***
***Continue testing***

## Summary 

***Summary ***

***Problem has seen extensive effort by a large group of people***
***Definitely related to Sorenson internal bus***
***Unable to precisely locate and fix problem***
***Further attempts to fix problem are counter-productive***
***Configuration changes this close to launch carry risk of other problems***
***Recovery procedure is in place, and exercised regularly***
***Problem cannot threaten launch***
*See command timeline, which shows no GPIB activity required to handle launch (following initial configuration)*
*Power up and SAS configuration completed >8 hours prior to launch *
*Recovery time is on the order of ~10 minutes*
*UC “crash” occurred during last Launch Sim, S/C launched successfully and on time!!!*

## Special Topic:

***Solar Array Cable Damage ***
- PR 1045-40-1

*** ******. . . Bruce Zink***
*EO-1 Electrical Lead, Swales Aerospace, Inc.*

## Solar Array Cable Damage

***Solar Array Cable Damage***

***Background***
***During final panel closeout inspections on June 6 a hair line mark (centered around three o'clock) was noticed on the 86 wire bundle that comes out of the SADA***
***The hair line mark was further inspected and determined to be a cut of the insulation for seven wires.  The geometry of the cut indicated damage due to a sharp object.  It must be noted that this cut was very difficult to see due to fine cut.  The location of the cut is approximately 0.75 inches off the face of the SADA interface which is approximately at the start of the bend radius for the cable bundle as it is folded up against the Solar Array Yoke.  This obviously is a high stress area.***
***Under higher magnification (10 - 20x) it was determined that at least three wires had exposed copper.  In addition oxidation has occurred indicating the damage was done some time ago.***

## Solar Array Cable Damage

***Solar Array Cable Damage***

***Background ****(continued)*
***All seven wires were verified as follows:***
*Connector Pin # Description - Function*
*Cable Wrap J2 7 Inboard S/A panel structural ground*
*Cable Wrap J2 37 Circuit 11+ (outboard panel fixed string)*
*Cable Wrap J2 19 Circuit 4- (Outboard panel, shuntable)*
*Cable Wrap J2 38 Guard (ground wire shield for CSS)*
*Cable Wrap J2 14 Guard*
*Cable Wrap J2 42 Guard*
*Cable Wrap J2 27 Coarse Sun Sensor 2+*

## Solar Array Cable Damage

**Detail View**
**“****A”**

***Solar Array Cable Damage***

## Solar Array Cable DamageClose-up

***Solar Array Cable Damage******Close-up***

**Detail View “A”**

## Solar Array Cable Damage

***Solar Array Cable Damage***

***Probable Cause***
***It is believed that this damage occurred while in the 238 TV chamber in the preparation of the Spacecraft for TV (October ‘99) or while clearing out the GSE blankets in and around the SADA .  This can not be verified and it is more than likely an accident which went unnoticed.  The SADA and cable wrap were thoroughly inspected via bore scope shortly before TV and was found to be nominal.***
*Prior to TV #1, a through inspection was performed in this area without issue*
*No work has been done in this area since leaving TV, until recently*
*Cutting instruments are generally used in chamber operations (TC number cutting, GSE MLI clearing,etc.)*
*One TV GSE cabling was found damaged in similar manner following TV*
*Configuration in chamber was not conducive to “ideal working  conditions for technicians” due to extremely tight configuration and poor lighting*
*QA oversight was from distance during T/V buildup and T/V teardown in chamber due to continuous monitoring of Oxygen level at chamber door due to concern of nitrogen Purge in closed chamber.  Safety of personnel was first priority!  Also there was insufficient room to have two people in the same physical area.*
***Other post TV activity require use of razor blades (Radiator tape cutting, excess adhesive removal/trimming, etc.) however this has been limited and is under constant monitoring by QA***

## Solar Array Cable Damage

***Solar Array Cable Damage***

***Corrective Action***
***Based on the type of damage & critical location it was determined by both Swales Aerospace & GSFC Quality (M. Kelly) that this damage could not be repaired by splicing or any other means. The wires associated with pin J2-7, J2-37, J2-19, & J2-27 would need to be replaced by swapping with existing spares within assembly.***
***Implementation of swap was made using a patch cable due to access restrictions.***
*Make use of current internal Bay 5 SADA cabling interface connection*
*Fabricated “Connector Bracket Assembly” which essentially swaps wires (J2-7, J2-37, J2-19 & J2-27) with the spares*

## Bay 4 View of SADA

***Bay 4 View of SADA***

**Detail View**
**“****B”**

## Bay 4 View of SADA

***Bay 4 View of SADA***

**Detail View “B”**

## Solar Array Cable Damage

***Solar Array Cable Damage***

***Corrective Action ****(continued)*
***In addition to the fabrication of “Connector Bracket Assembly”  the following other actions were taken***
*Millohm & insulation resistance (cross pin) testing of entire cable to verify all wires prior to initiating of change & rework of damaged cables*
*Although J 2-7, J2-37, J2-19, & J2-27 wires were abandoned, exposed copper & insulation wiring was covered. Guard wires were also reworked.*
*Millohm & HiPot entire cable following rework. (Connector Bracket Assembly testing which also includes HiPot testing performed prior to delivery to Spacecraft)*
*Integrated Connector Bracket Assembly with Cable Wrap Assembly*
*Verified all SADA signals with Connector Bracket Assembly installed*
*Followed by full SADA functional*
*Following completion of S/C bay closure a S/C Aliveness Test was performed*

## Solar Array Cable Damage

***Solar Array Cable Damage***

***Corrective Action ****(continued)*
***Other Global actions taken:***
*Inspected all external cabling prior to blanket installation.  *
*Fabricated Red Tag Item to cover critical area of Solar Array cable.  It will be removed prior to Solar Array installation. *
*Rework of cable harness will have no effect to overall deployment of Solar Array*
*Deployment Hinge has >4x Torque margin for worst case environmental effects*

## Connector Bracket Assembly Fitcheck on SpacecraftMonday 6/12/00 - 1400

***Connector Bracket Assembly Fitcheck on Spacecraft******Monday 6/12/00 - 1400***

## Summary

***Summary***

***All repairs and preventative measures implemented successfully***
***All changes documented in appropriate drawings***
***Extensive spacecraft testing has taken place since repair, including a full TVAC test with no anomalies related to the cable wrap assembly***
***Negligible residual risk***
***Ready to fly***