1、Lessons Learned Entry: 0282Lesson Info:a71 Lesson Number: 0282a71 Lesson Date: 1993-07-12a71 Submitting Organization: JPLa71 Submitted by: Jim TaylorSubject: Relay Hangup Upon Power Removal Abstract: One Voyager Solid State Amplifier (SSA) failed to operate upon application of input power during spa
2、cecraft system test. Post-test analysis determined that a relay hangup had occurred following the previous application of power, and the original analysis had not considered decaying stored energy in the relay. Take all operating modes into consideration in circuit design. Design relay circuits so t
3、hat the circuit can still apply energy to activate relay coils, even if the relay hangs up between contacts.Description of Driving Event: One Voyager 20-watt Solid State Amplifier (SSA) failed to operate upon application of input power during spacecraft system test. The SSA provides RF power for the
4、 downlink. This problem had not occurred during many previous power applications to this SSA nor on any other SSA. In flight, this failure would render the SSA useless. Post-test analysis determined that a relay hangup had occurred following the previous application of power. The relay anomaly invol
5、ves OP-AMP operation below normal voltage, energy stored in capacitors, and the relay switching voltage threshold. The original analysis had not considered decaying stored energy.Lesson(s) Learned: Circuits can behave in an unexpected and unacceptable manner when applied power is removed and the sto
6、red energy decays.Recommendation(s): 1. In the design of circuits, all operating modes must be taken into consideration.2. Relay circuits should be designed so that the circuit can still apply energy to activate relay Provided by IHSNot for ResaleNo reproduction or networking permitted without licen
7、se from IHS-,-,-coils, even if the relay hangs up between contacts.Evidence of Recurrence Control Effectiveness: N/ADocuments Related to Lesson: N/AMission Directorate(s): N/AAdditional Key Phrase(s): a71 Energya71 SpacecraftAdditional Info: Approval Info: a71 Approval Date: 1985-12-19a71 Approval Name: Carol Dumaina71 Approval Organization: 125-204a71 Approval Phone Number: 818-354-8242Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
