I am electrician and I work at testing field of a frequency converter factory. Recently one of my colleagues wondered if the product of our factory is actually a hoax. Because electrical load our testers use are either electric motors or chokes in soundproof enclosures, so we really don't see anything happening except on computer screen, which would be easy to program to show canned data. That reminded me of certain hoax claims regarding compartmentalization and how workers wouldn't know if the top few had designed useless prop.
How do I know our frequency converters are real? Firstly we were taught installing and basic configuration in vocational school which had zero affiliation with said manufacturer. Altough I really don't know control theory or electronics of FCs, the high power side is in harmony with everything I know about electricity.
Sadly our assembly workers don't really know or care what they are assembling and work mostly on rote memory which leads to many errors. That leads to second point: when FC is assembled correctly and all components are working it passes all the tests. If there is error in assembly or defective component, it won't work. Also different errors or defects cause different defects. If the power supply wire harness to "brain" card hasn't been installed, the unit won't wake up or receive software. If there is loose connection in high current busbars it results either explosion or current imbalance trip. If thermal paste is missing or there is debris between IGBT and heat sink, that IGBT will run hot and cause a trip etc. After rectifying the defect, the unit passes.
Third thing is, production line I work for produces units to order. If they are delivered late or have undetected defects, the customer complains. We workers don't interact with customers but after a gaffe there are white collars prowling in production asking guestions, making changes to procedures and the gaffe will be harped on in staff meetings.
In conclusion I know our product is real because there is independent evidence of it's existence, it works according to principles of electricity I was taught in vocational school and it passes tests if it is defect free. If there are defects, trouble they cause is in line of what I know about electricity. If defect passes, there will be fallout from customer.
I don't know how aerospace works but based on my experience, a competent tradesman knows whether or not they are building something that works or not.
Lurky
