You guys have done things right. You made sure you took your time, listened to the users and got it right.
Great idea. We figure about 1 in 4 transformers are usually faulty. If you will know which one has the fault, you won’t waste any time on that transformer.
Up to now, there has not been a sound, reliable test (without disconnecting the transformer and applying voltage) to detect faulted pole-mount transformers.