International space station (ISS) truss orbital replaceable unit (ORU) overvoltage transient resolution

On the international space station (ISS), power quality specifications are designed to ensure system stability and operability of electronic hardware. System-level test data and model analysis results are verified against the power quality specifications. The process of mitigating power quality violations involves two main options: 1) redesign the hardware to meet the requirements or 2) process power quality requirement exceptions after a thorough and careful impact analysis on the system and its loads, called orbital replaceable units (ORUs). During the ISS system integration testing, system voltage transients were observed on the secondary bus that violated power quality requirements during start-up of one of the ORUs. The system overvoltage transient test data are presented and analyzed. The system overvoltage resolution plan is outlined. Finally, the impacts of the voltage transients on other ORUs connected to the power bus are assessed.