ATS on single UPS

[Anonymous user]

I have one question. 

Can one ATS be connected to two different PDUs that are then connected to a single Symmetra 160K UPS? 

If I take out one power supply from ATS will it still provide power from another?

Thank you

[Brad_C]

It doesn't really matter how you supply power to the ATS inputs, as long as one of them has power that is within tolerance it will be routed to the output.

[Anonymous user]

That's what I thought. But funny thing happened. When I pulled out one power supply all equipment turned off and the ATS was powered. Is it maybe something with the ATS itself (hardware wise) or can be something with the configuration? 

[Terry_Kennedy_apc · Accepted solution]

The ATS has 2 DC power supplies, one powered by each source. If one of the power supplies is bad, when the source with the good supply drops, the ATS will lose power and will drop the load even though the other source is OK. However, a bad DC supply should raise an alarm. You could look in device status and see if it reports them both as OK.

It is good practice to have both sources on the same phase (the ATS will report "Phase sync: In sync"). Due to how fast the ATS needs to operate when switching sources, it is possible for both sources to be briefly connected due to physical delays in the relays in the ATS. If the sources are out of sync, unpleasant things can happen. That's also the reason for the warning to disconnect one source when updating the ATS firmware. If it is appropriate in your situation, you can also configure "Preferred source: None" which will prevent an un-necessary transfer back to the preferred source once that source is providing power again.