Is the DL3000RM3U generator compatible?

[mlewis_apc]

I've been looking at the forums, reading all I can about this but the only way to confirm is to ask.

I have a single 8Kva UPS taking care of a server room, with a generac 12Kw generator as backup.
It is a single phase UPS with an average of 20Amps on each phase on the load for a total of 5000Kva.

I've run tests and while I only have 3 minutes of battery time, with the geny running, I am able to get some 10 minutes out of the UPS as it keeps trying to use the geny but fails, yet gets enough to charge it's batteries just a little, thus, getting that 10 minutes from 3 minutes of actual battery time.

The problem seems to be that the geny is putting out noisy power. I've looked at this also and without load, it is fluctuating between 62/63Hz. The manual says to adjust it to 63/63.5 without load. Some folks have been telling me I should in fact get it closer to 61Hz. This I can do.

Either way, the current UPS won't sync up with the geny. I have a few DL3000RM3U units in my racks which aren't being used at this point. Is there any chance that they might be more willing to work with my geny and if so, I could easily transfer the loads from the main UPS, turning it off and allowing the APC's to take over.
I would probably run 4 units, with about 1200Va or so on each. A little more if I could get away with it but that's what I would need constant at least.

I know about sizing the geny to the UPS and my ultimate hope is to slowly lower the consumption amount which is why I didn't why to invest in a 2-3 times size geny.

Mike

[BillP]

The DL units have a sensitivity setting you can play with. Dell DL units dont have the sensitivty LED/button them to adjust it so you'd have to configure this with software. The units, out of the box, are set on "high" which may cause an issue with a generator. The other settings are medium and low.

[Here is an article on sensitivity settings.|http://nam-en.apc.com/cgi-bin/nam_en.cfg/php/enduser/std_adp.php?p_faqid=62] You'd need either a network management card in the UPS or Powerchute Business Edition with either a USB cable or a serial cable attached to a computer so that you can change this setting to medium or low, because majority of the time, high wont work that well with a generator.

The DL units have a tolerance of +/- 3 Hz for frequency, so you'd want it within that range - 57-63Hz

What is the larger UPS you have? Is it an APC UPS, possibly a Symmetra?

[mlewis_apc]

So I bit the bullet and tested the APC Smart-UPS 3000 units on the geny.

Taking the transfer switch out of the mix, I wired the common and two hots direct to a new breaker panel which feeds the Smart-UPS 3000 devices. I had that panel setup because I wanted to feed those separate from the main UPS.

The generator cabinet ground goes to an earth rod. However, the transfer is connected to ground/common so it does go back to the geny. So what's happening is that the geny has an earth rod ground and a shares ground with the utility. Not quite sure if I should connect the utility ground to the geny chassis as well?

So, powered it up, waited a few moments, then switched the breakers on. Had to adjust the sensitivity on the UPS devices to medium in order to get them to sync up to the geny. Once they did, I applied some loads and all went just fine.
I was happy that I only had to set to medium as this seems to mean that the geny will do fine with these machines.

The geny is a 12Kw unit so I am hoping to power 4 Smart-UPS devices, each with about 1200/1500Kva max in order to allow for plenty of battery backup for geny turning on and off. Basically, around the 5000Kva range which the geny should be able to handle ok.

I'm not sure what else I might need to do? Do these units have to have their loads balanced across the plugs on the rear or anything like that?

Mike

[BillP · Accepted solution]

i'd have to dig up something on monday but as far as i can tell from the picture on the website, the circuits on the back of the UPS should be labeled and have their own breakers. so two or three outlets may have their own breaker and then another two or three.

i was looking at the APC branded unit, SU3000RM3U

http://apc.com/resource/include/techspec_index.cfm?base_sku=SU3000RM3U&tab=documentation