You are correct Sir. I got a hold of a local Unity Guru and the power supplies work in parallel/tandem with two out of the 3 supplying the juice. When I only restored one of the 3 ups units it fired up but ended up overloading the ups and I found it didn't trip the circuit breaker at the box but the breaker at the top of the rack power strip. Taking all the loads off the ups units allowed me to fire them up and run self tests etc... Then I shut the all off and reconnected and turned them all on at once so no one unit bares the heavy load. I don't know what decides which of the 3 power supplies are the two active units. Is that hardware slot based or who gets power first? Given the rats nest of ac cables I didn't take the time to see if there was a rhyme or reason as to how the ac power was distributed across the ups units but I assume each unit feeds one of the 3 AC inputs on each chassis. For those more savvy would it make sense to have the top power supply in each chassis go to ups 1, the middle plug to ups 2 and the bottom plug to ups3? Would that make two of the ups do all the heavy lifting unless there was a failure then the redundant backup would fire up.
---In Avid-L2@yahoogroups.com, <jb30343@...> wrote :
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Friday, March 31, 2017, 3:06 PM -0500 from bigfish@... [Avid-L2] <Avid-L2@yahoogroups.com>:
That may be correct but then when I got one of the units powered up it should have worked without showing an overload and ultimately taking down the breaker. If the power supplies are truly redundant then I should not have seen the behavior I did.
It looks like each of the 3 ups units in the rack feed one of the three ac inputs to the unity chassis. Perhaps one of the Unity gurus can shed some light on this. Perhaps we have been running on the very edge with our power draw and for whatever reason without all the ups units up it somehow overburdens the one that is back up. Some sort of load sharing is the only thing I can think of. Perhaps the unit I powered up is hooked to backup supplies in some of its' outputs and without the primary ups on it gets more load than normal that would explain the behavior if the power feeds are truly just redundant.
---In Avid-L2@yahoogroups.com, <cutandcover@...> wrote :I don't think there's any such thing as parallel power done this way. Those would be redundant power supplies. Each one on its own can power the chassis. Try it plugged straight into the wall, just one of them.You use redundant power supplies so that in case one fails, the other can still keep the unit operating.On Fri, Mar 31, 2017 at 3:13 PM, bigfish@... [Avid-L2] <Avid-L2@yahoogroups.com> wrote:Looking further in the rack it appears each unity chassis has 3 power cord inputs so I imagine all 3 of the problematic ups units are feeding a 3rd of the power to the chassis. Hence when all go out at the same time due to the power hit each unit is overwhelmed when trying to power back up. Just a guess but it makes sense in my head.
Posted by: bigfish@pacbell.net
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