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Power Supply PSS Certification. PSS Certification. PSS test conducted twice a year to verify operation of PSS enables and operation ARC1 Fails PSS certification. Will not turn off when PSS signal is disabled - PowerPoint PPT Presentation
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Power Supply PSS Certification
PSS test conducted twice a year to verify operation of PSS enables and operation
ARC1 Fails PSS certification. Will not turn off when PSS signal is disabled
Power Supply computer indicates that off signal has been sent, but hardwired signal indicates that Main Contactor is not de-energized. PSS will not drop to OFF/Safe status
Main contactor disables after a while, and problem is not easily repeatable.
PSS Certification
Power Supply Indicators
Power Supply Failure Indications
Main Contactor is sticking and does not decouple when control voltage is disabled.
Investigation finds that Auxiliary contacts have been attached onto Main contactor using screws that were too long
Long screws break through Bakelite material and small pieces onto rails of the armature assembly of the Main Contactor. This may have contributed to some of the “stickiness”, but not conclusive.
Failure Analysis
Main Contactor Sticking
Recreation of Sticking Contactor
Main Contactor Pictures
Debris
Main Contactor Picture
ALL power supplies with Auxiliary contacts have been checked for correct screw lengths.
9 Additional Supplies found to have incorrect screw length and minute debris in the Main Contactor
All Contactors cleaned, voltage tested and replaced
Additionally, power supply schematics are being revised for quicker diagnostics in the future
Corrective Actions
Changes or additions to existing equipment must be fully analyzed for correct configuration
Non-routine tasks must be evaluated before work is conducted
Test all equipment before installingUpdate schematics
Lessons Learned