Primary Distribution Voltages in California 5

[dmortimer]

Our company is evaluating the feasibility of supplying some temporary equipment into the California area around Fresno that will reqire a source of electricity at primary (above 750 volt) levels. Can anyone tell me what the predominant primary distribution voltages are in California? For example, 12.5 kV, 13.8 kV, 25 kV, etc. Who would we contact to source the power and provide transformation to the voltage levels we require and at the kVA levels we require?

Thank you, Doug from Canada

 

[jbartos]

Suggestion: Visit

http://ora.ca.gov/distribgendocs/PhaseI_ORA DG OIR_Ch7.pdf

for:
23.9 kV, 13.8 kV, and 4.16 kV.

 

[busbar]

The area is likely served by Pacific Gas and Electric—probably 12000Y/6930 or 20780Y/12000.

Their boilerplate is §B in

http://www.pge.com/tariffs/pdf/ER2.pdf

 

[alehman]

34.5kV is common in the Los Angeles area.

 

[davidbeach]

Having once worked in Fresno, busbar is very close. The two likely voltages are 12000V delta and 20780Y/12000V, with the remaining 12000V slowly being converted to 20780Y/12000V. As temporary installations, you are likely to get one or the other and not have to worry too much about it changing. Any permanent installation in 12000V territory should be designed with the capability (dual primary rated transformers) for conversion to 20780V.

 

[alehman]

A recent project I worked on in Santa Clara was also 12.0kV.

 

[busbar]

Aside — In NorCal a rule of thumb for larger data centers is 600 amperes for feeders, as a load limit for 12 or 21kV distribution circuits. For larger loads, subtransmission or transmission voltage is needed.

 

[dmortimer]

Thanks again, everyone! It seems like 12/21 kV is the most likely. We are trying to make contact with the utility in Fresno at the moment. In our area here in Canada we have a combination of old 12.5Y/7.2 kV and new 25Y/14.4 kV systems. BC Hydro is upgrading to the higher voltage system, but you'll note that the new system is a 2 times multiple of the old. Thus, most of our existing equipment will not tap down far enough to reach the new 21 kV system being installed in Fresno. However, if it turns out that we are located on an older feeder at 12 kV, we can tap down from our 12.5 kV voltages to reach 12 kV comfortably. We'll keep our fingers crossed. Thanks again to everyone who responded.

 

[jbartos]

Suggestion: Considering the temporary power for the temporary equipment, it may be a good idea to check with the Fresno Utility, whether or not the more standard voltages elsewhere, e.g. 13.8kV, are available and can be provided.

 

[davidbeach]

Standard voltage somewhere is what the utility provides at that location. In Fresno the standard voltages are 12kV and 20.78kV (referred to locally as 21kV). 13.8kV is not a standard and would not be available, why would the utility build a special substation just to serve a temporary load? It's just not going to happen. In fact, as a temporary load, you will pay all utility costs, there will be no line extension allowances or credits as the loads won't be there long enough for the utility to recover their costs.

 

[jbartos]

Comment: The Utility can provide non-standard voltages if applied for and paid for.

http://www.rp-l.com/commercialrates.htm

for:
Should the Customer require a non-standard voltage, Customer shall, at his own expense, furnish and maintain all transformers and protective equipment therefore necessary in order to obtain such nonstandard voltage.

 

[busbar]

Review of some links might save a few phone calls…

http://www.pge.com/docs/pdfs/custom...ces/greenbook/service_requirements/sect13.pdf

http://www.pge.com/docs/pdfs/suppli.../solar_wind_generators/expanded_e_net/toc.pdf

[Clearly, the IPP/QF aspects of this info do not apply.]

Provisions for EUSERC metering in medium-voltage service equipment/metalclad gear may be more complex than in some other areas.

 

[davidbeach]

jbartos, what relevance does a Richmond Indiana utility have to a question about utility practices in Fresno Ca? Sure, if you want to define it broadly enough, the utility will provide 13.8kV if you are willing to pay for a 12kV (or 21kV) to 13.8kV transformer. But what's the point if the 13.8kV is then just going to be transformed down to another utilization voltage? What is gained by the second level of transformation?