ATS7750 Unexplained source switch

[TheDan_apc]

We have an ATS7750 that every few days switches sources from preferred and back within a few minutes. No other log entries are present for this switch. We are in a datacenter environment with conditioned power. We have checked with the datacenter and they do not have any reports of power issues from other customers.

We bought the device used but a review of the logs indicate it has been doing this for quite some time, the events stretch back into the time the previous owner used it. 

It is not affecting the attached equipment but I don't think it should be doing this. Is this a configuration problem or could there be a hardware fault with the device?

I have attached sanitized versions of config.ini, data.txt, and event.txt.

Thank you,

Dan

[Terry_Kennedy_apc · Accepted solution]

You have sensitivity set to high, which may cause the ATS to "jump the gun" when it sees something that might lead to causing a transfer. For example, if it doesn't like the rise time of an AC cycle (perhaps due to something else causing a transient drop/spike) it may proactively do the transfer. Since it switches right back, that means it discovers its prediction was inaccurate and switches back to your preferred source.

You might also try updating the firmware. It looks like it is rather old. The firmware for the management card does not have anything to do with these switchover events, but updating the firmware card will also update the firmware in the actual transfer switch microcontroller (if it is out-of-date). Be sure to read the caution on the firmware download page - basically, you need to disconnect the source that is not in use before performing the upgrade, then reconnect it after a successful upgrade. Otherwise you can weld the source selection relay contacts.