3phase 120/208y service generator install.
- Thread starter ctaylo360860
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ctaylo360860
Senior Member
- Location
- colorado
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- ME
They won’t be plugged into genset directly. they will be in a sub panel that is fed by genset. Why wouldn’t you? Actually curious not being a smart a...
I will reword my earlier statement "I wouldn't supply thousands of dollars of servers and POS with a $900 generator"
The power coming out of these generators isn't "clean" or stable with regard to voltage and frequency, and god help you should the generator run out of fuel or the engine die while powering the load. It is generally understood that sensitive electronics should not be supplied by these types of generators. The right thing would be something like a "real" generator, diesel plant with frequency control and voltage/frequency monitoring. Or for such a small application like this I would consider using a Honda EU7000is which is a gas inverter generator with split phase output via a L14-30.
zbang
Senior Member
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- Roughly 5346 miles from Earls Court
The OP has already stated that the equipment is fed by a UPS, so I assume they'd feed that with the genset (via a transfer switch, etc).
ctaylo360860
Senior Member
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- colorado
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- ME
Yes sever wise everything is plugged into apc Schnieder battery back ups... I believe pos are as well....
zbang
Senior Member
- Location
- Roughly 5346 miles from Earls Court
smartups are generally line interactive (unless specifically one of the handful of online models) they will constantly cycle between line and battery when running on a small construction generator. And when they are on utility/gen theyre passing that through to the load. APC has some whitepapers on this, detailing how if you are going to run ups from small gas generator you have to go into powercute and turn the pq sensitivity all the way down, and oversize the generator 3x-5x. I will try to find the docs tonight.
might also want to check with h/w vendor to see if warranty will cover blown up power supplies if run from a small generator.
might also want to check with h/w vendor to see if warranty will cover blown up power supplies if run from a small generator.
zbang
Senior Member
- Location
- Roughly 5346 miles from Earls Court
(sorry about the quoting above, it's too late to fix)
b) the OP is talking about running what's probably 2KW on an 8KW generator (which many people would not consider "small"), we're not talking about an 800w lunchbox-size generator. As long as the loads are relatively constant, the speed & voltage will be, too. Just don't try starting a walk-in cooler compressor or something like that.
To the OP-
Which model UPSs are they really?
Have you done an actual load survey or are you leaving that to the customer?
Yes, generally line-interactive; not as good as Liebert full on-line, but pretty good.
a) evidence, please (I suspect the generator would need to be having a lot of problems to cause this).
b) the OP is talking about running what's probably 2KW on an 8KW generator (which many people would not consider "small"), we're not talking about an 800w lunchbox-size generator. As long as the loads are relatively constant, the speed & voltage will be, too. Just don't try starting a walk-in cooler compressor or something like that.
Which is exactly what it sounds like.
To the OP-
Which model UPSs are they really?
Have you done an actual load survey or are you leaving that to the customer?
from https://www.apc.com/us/en/faqs/FA158891/
A common characteristic of generators is the normal output voltage distortion when supplying power to nonlinear loads such as computers. This output voltage distortion can be interpreted by the UPS as unacceptable power quality, forcing the UPS to transfer to battery operation. When the load is transferred to the battery, naturally the generator distortion will be reduced or disappear, leading the UPS to attempt to transfer back to line operation. When the load is reapplied to the generator, the distortion will return, leading the UPS to once again transfer to battery. This cycle may repeat indefinitely at intervals of approximately 4 seconds. The answer in this case is to choose a generator which will not distort, when the nonlinear computer load is applied.
Another C10
Electrical Contractor 1987 - present
- Location
- Southern Cal
- Occupation
- Electrician NEC 2020
well .. Not sure which is more cost effective or practical,
Get a 3 phase generator as mentioned earlier or
Install a separate 120/240v single phase distribution panel dedicated to the servers and registers fed from a new transformer boosting the 208 to 240, then generate that new 120/240 distribution during failure.
Another point id like to make is the generators under discussion don't even publish their voltage regulation tolerance or frequency stability. You're relying purely on a mechanical governor to maintain the engine at 3600 rpm for your 60hz and very little rotating mass or inertia to dampen load transients. The APC smartups will only tolerate +/-3% variation of line frequency. Last, I just finished reading the manual for the pulsar (wanted to see the diagrams) and it happens to contain a disclaimer about not being responsible for damage to sensitive electronics and requiring use of a "approved line conditioner" whatever that is...
Strombea
Senior Member
- Location
- Prescott, Arizona, USA
Sorry corrections made... I should use a switched neutral double throw it will be considered a separately derived system and I will need to make sure grounded conductor snd egc at the genset frame are bonded and isolated at sub panel and double throw?
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Why would you want it to be separately derived?
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Switch Neutral Transfer Switch?
www.mikeholt.com
Why would you want it to be separately derived?
hillbilly1
Senior Member
- Location
- North Georgia mountains
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- Owner/electrical contractor
I had that issue on one install, the job was sold by another contractor, but they could not fullfill the install schedule (about 100 installs for a big box chain) 12 Kw Generac, the customer ran a business out of his basement, had a large server and UPS, with six workstations. UPS did not like the generator!
ctaylo360860
Senior Member
- Location
- colorado
- Occupation
- ME
Switch Neutral Transfer Switch?
www.mikeholt.com
Why would you want it to be separately derived?
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I can tell you I was on vacation with no code book. After looking at my book I would also agree that I need a solid neutral double throw... and it would be a non separate derived system.... for some reason I though it had to have grounding and grounded conductors bonded to be a non sep system... .... I just need to have a solid neutral. The service disconnect should have grounding and grounded conductors bonded and then everything else from there on out should have grounded and grounding conductors isololated
rlqdot
Member
- Location
- St. Louis, MO - USA
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- Professional Engineer (multiple states) - building design
I know I am extremely late to this party, but does anyone else see any problem with the operator wanting to keep power on to the point of sale equipment, which would imply occupants inside a building, without also providing power to the egress lighting circuits? "Lunchbox" or "bug eye" emergency lights are intended to evacuate occupants from the building, not provide lighting for continued occupancy. I would be cautious of giving them a power source they think will allow them to stay in the building - in the event the generator AND emergency lights fail and someone cannot exit during an emergency (isn't failed lighting considered an emergency?) be prepared to be named in the law suits that follow - IMHO.
- Location
- Placerville, CA, USA
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- Retired PV System Designer
One more wrinkle, if there is equipment that will accept it, would be to install a three phase UPS constantly online with battery charging, and then charge it normally from three phase grid power but at a reduced capacity from single phase generator power during an outage. Sort of like using a VFD to drive a three phase motor from a single phase source.
It might not be able to fully maintain the batteries, but it could extend their run time significantly.
It might not be able to fully maintain the batteries, but it could extend their run time significantly.
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