Εδώ το purge αναφέρεται στον καθαρισμό ενός μετασχηματιστή ρεύματος και το credit στο περιθώριο αναβολής/αποφυγής του καθαρισμού, επειδή δεν χρειάζεται.

purge -> καθαρίζω, εκκενώνω
purging -> καθαρισμός (Αγγλοελληνικό Λεξικό Όρων Ηλεκτρονικής, https://www.academia.edu/29744298/English_Greek_Lexicon_of_E...

"The purge credit, simply defined, is when, during a normal CT shutdown, there is sufficient CT post-purge airflow to remove any residual combustible materials from the CT and HRSG system. If gases cannot seep into the ductwork, then the post-purge meets the NFPA requirements and a redundant start purge is not required." (...) "When these enhanced system isolation upgrades are completed, the revised NFPA 85 (2011) provides a purge credit that allows startup to proceed without an additional purge prior to CT light-off." (https://www.powermag.com/startup-purge-credit-benefits-combi... (CT -> Μετασχηματιστής Ρεύματος)

"In fire and explosion prevention engineering, purging refers to the introduction of an inert (i.e. non-combustible) purge gas into a closed system (e.g. a container or a process vessel) to prevent the formation of an ignitable atmosphere." [https://en.wikipedia.org/wiki/Purging_(gas)]

purging gas -> αέριο καθαρισμού (https://glosbe.com/en/el/purging gas)

"Purging is the act of removing the contents of a pipe or container and replacing it with another gas or liquid. Purging is crucial in pipeline, piping, welding and industrial process. It removes contaminants from the piping and vessels, which reduces chances of corrosion. Purging can prevent a hazardous mixture of gas and air." (https://www.corrosionpedia.com/definition/950/purging)