Residential Generac 22kw generator in Commercial Application...any thoughts

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TrickleCharge

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I have a small IT business that is proposing to install a residential 22kw 120/240 3W standby generator shown below. They are going to be using it to back up a 150A server subpanel. They had some issues with their plans in regards to their service tap conductors along with some feeder callouts. This comes in a kit that has a matching ATS that goes with the generator. I have never seen one of these residential units used in a commercial application....anything I should be looking for specifically...just odd that they are using the residential unit.


Z
 
It is probably one of the classic "you get what you pay for" deals.
My first concern in a commercial application would be to verify the actual load on the panel and determine if any of that load is motor load such as HVAC. Secondly, since IT is involved, I would want to make sure to discuss the "quality" output in the event the IT equipment is connected directly to the incoming power.
I have often seen instances where IT equipment does not "play well" with generators.
 
generac is great... don't pay mind to the old timers who aren't used to them in the commercial market. Generac specializes in paralleling small generators which is great when expanding your business or wanting redundancy of generators. they also have many different kinds of transformers which can provide considerable benefit. for example one can shut off two loads automatically so that the generator can handle the load. for example maybe an elevator, the AC compressor or a non critical sub panel.
 
the generator service techs in my classes don't like Generac. Generac is hard to get tech support for. Many of their generators are 2 pole, meaning when it runs its going 3600 RPM.
 
The item I would suggest giving consideration is how much amperage the IT equipment will draw. Typically a standard generator such as the residential model, with automatic voltage regulator can be loaded ,think 25% with skewered neutral loads such as computers, ups, servers. Typically a permanent magnet exciter generator is used in these applications, allowing for greater amperage from IT equipment. Have seen phone switch stations have generator voltage regulator issues from this. Causes voltage regulator to ramp voltage up, shutting down ups systems .
 
TrickleCharge said:
I have a small IT business that is proposing to install a residential 22kw 120/240 3W standby generator shown below. They are going to be using it to back up a 150A server subpanel. They had some issues with their plans in regards to their service tap conductors along with some feeder callouts. This comes in a kit that has a matching ATS that goes with the generator. I have never seen one of these residential units used in a commercial application....anything I should be looking for specifically...just odd that they are using the residential unit.


Z
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Several things to keep in mind here.

A) What fuel supply is being used? If Natural gas this 22Kw unit is only rated at 19.5Kw.

B) This unit as with most industry residential generators is listed and cataloged as an HSB (Home Stand-By) unit.

C) Stand-by units continuous load MUST NOT exceed 60% (22Kw unit = 11.7Kw continuous load) of the full load rating except as noted below.
1) One hour out of every 12
2) Two hours out of every 24
3) 250 hours out of any 12 month period

D) Your fuel supply and piping to the generator MUST be capable of supplying 100% of the full load fuel requirements of your generator.


Most IT equipment contain switching power supplies which can cause serious problems with small standby generators. I would highly recommend that you measure the load on the 150a panel during full system operations and realize that unlike a residence where the loads are mostly light except for motor starting this load will be steady at a much higher level 24/7 during any power outage.

I suspect that the owner is trying to get by on the cheap and this proposed install will have major problems.

Best bet here is to consider the following:

1) Get your load information from the panel in question during normal system ops on utility power.

2) Contact the server mfg. and get their exact power requirements for the servers, including the power quality specs.
a) Voltage
b) Frequency
C) Total Harmonic Distortion (THD)

3) With the information noted above in hand contact the generator manufacturer's Tech Service Dept. for their recommendations.
 
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