I have an auto-switching 3600W isolation transformer which has been working well for a couple of years. Lately it has started to cycle on/off about every 2 seconds when powered up. The green power LED is on, the yellow 120V LED cycles and the red temperature LED is off. Several relays can be heard clicking within the transformer. The transformer is cool (20 degC) and the fans are not running. I’ve checked input shore power and it is stable at 118.4 +/- 0.1 VAC, 60Hz.
When this problem first started, it would happen once/24h, usually around 1AM. At that time our current draw is around 3A. I would simply disconnect shore power and go back to bed. In the morning on power up it would work normally, even with 20+A loads.
Lately, the frequency of the cycling has increased and it could happen at any time of the day with no discernible relation to whatever loads were on or off. It has now reached the point where it begins this cycling behaviour as soon as it is powered up and I have had to bypass it completely.
Any thoughts/suggestions on what the problem might be?