From: Corkran, Jerry L [mailto:Jerry.Corkran@CooperIndustries.com] 

Sent: Tuesday, December 13, 2011 9:36 PM To: jerry.schoen@aksteel.com Cc: Andrew Delaski; Alex Hofmann; Aris Marantan; Art Rosenfeld; Robert Berman; Brenda Edwards; Brian Coffey; Hirsch, Bolduc; Caitlin Johnson; Carlos Gaytan; Charlie Drexler; Chris Brown; Simmons, Chuck; Clark Silcox; Charlie Stevens; Dan 

Flaten; Dan Mulkey; Daniel Young; Emily Marchetti; Eric Peterson; Gary Fernstrom; Greg Rosenquist; Greg Coulter; James Freeman, Jeremiah; Jerry Hodge; Creevy, Jim; Jim Raba; Joanna Mauer; Caskey, John; John Cymbalsky; John Rossetti; KaMahesh P. Sampat; Matthew Nardotti; Maxine Savitz; Michael Hyland; Michael Rivest; Meg Waltner; Pamela Costello; Ryan

Hopkinson; Puesh Kumar; Polinski, Raymond; Rob Greeson; Richard Parker; Rick Anderson; Bob Saint; Robert van Buskirk

Nadel; Steve Rosenstock; Tim Ballo; Tom Eckman; Ted Johnstone; Thomas Petrosino; Wes Patterson; Zhimei Luo Subject: RE: FW: Distribution Transformer loading 

Jerry,The memo called attention to the PG&E practices, because we believe that what they are doing is what most of the other 

it is an intelligent way to use the smart meter capabilities. It is smart not just for the transformers, but also for the cable 

The DOE study locked in a 50% target for the maximum efficiency, likely because that is what the 2007 study used for the 

50% maximum efficiency target is wrong now for new transformers purchased by PG&E and it is either wrong now or it w

the entire industry. It is logical that the industry will follow the PG&E lead and load their transformers to a load which giv

of their equiptment. If a 70% average RMS load is the expected target when smart meters are in widespread use, then t

maximum transformer efficiency at 70%.

Another reason we encourage the DOE to use the correct average RMS load is so that the transformer efficiency payback 

accurate. If the predicted average transformer loads are incorrect, then the payback calculations are incorrect such that 

efficiency performance of the designs evaluated.

Thanks to Katie Coughlin who sent out the email which is copied below. It explains the percentages of full load for the tr

the DOE calculations. Katie’s sample population was 10,000 transformers while the PG&E population data was 6 million t

Hello all,Load losses are calculated based on the annual average of the squared load, i.e. the RMS. The LCC analysis sum
population of 10,000 transformers, each of which is loaded differently, so we work with a distribution of RMS loa

The shape of this distribution is approximately triangular. The shape of the distribution was developed based on 

building loads for several hundred commercial, residential and industrial buildings. The building load data can give us the average load is relative to the peak load. For the transformer analysis we 

the peak load relative to the transformer capacity. In the LCC, this "peak load factor" is also chosen from a distr

Uncertainty about how transformers are sized relative to their peak loads is handled by defining an additional pa

entire RMS load distribution up or down. The value of this parameter determines the average RMS loading, relafor the transformer population. Initially the Department's estimates for the population-average RMS loading were taken from the previous rulemrulemaking, the utility representatives on the committee have provided us with data on transformer loads, primacapacity units connected to residential loads. Based on their input, our current assumptions are: - for smaller capacity transformers the average RMS is about 32% - for smaller capacity transformers in low population density areas the average RMS is 25% These assumptions apply to design lines 1 and 2. Note that these design lines also serve small commercial and m

not have data on average loading for those customer classes. For the larger capacity transformers and 3-phase transformers, the loading is currently set to about 40% populado a sensitivity with the RMS load set equal to 50%. We do not currently have data for the larger capacity range

regards, Katie

Recommendations: The DOE should correct the average and peak load factors used for all lines anticipating that the good 

managers will lead them to follow the PG&E lead to result in an electric utility industry loaded at about the 70% of full loa

payback calculations and the maximum efficiency target points should also be corrected.

Thanks for reading this,

Jerry Corkran
From: jerry.schoen@aksteel.com [mailto:jerry.schoen@aksteel.com] 

Sent: Tuesday, December 13, 2011 3:06 PM To: Corkran, Jerry L Cc: Andrew Delaski; Alex Hofmann; Aris Marantan; Art Rosenfeld; Robert Berman; Brenda Edwards; Brian Coffey; Hirsch, 

Bolduc; Caitlin Johnson; Carlos Gaytan; Charlie Drexler; Chris Brown; Simmons, Chuck; Clark Silcox; Charlie Stevens; Dan 

Flaten; Dan Mulkey; Daniel Young; Emily Marchetti; Eric Peterson; Gary Fernstrom; Greg Rosenquist; Greg Coulter; James 

Freeman, Jeremiah; Corkran, Jerry L; Jerry Hodge; Creevy, Jim; Jim Raba; Joanna Mauer; Caskey, John; John Cymbalsky; Ken Winder; Mahesh P. Sampat; Matthew Nardotti; Maxine Savitz; Michael Hyland; Michael Rivest; Meg Waltner; Pam Cos

Phil Hopkinson; Puesh Kumar; Polinski, Raymond; Rob Greeson; Richard Parker; Rick Anderson; Bob Saint; Robert van Bus

Steve Nadel; Steve Rosenstock; Tim Ballo; Tom Eckman; Ted Johnstone; Thomas Petrosino; Wes Patterson; Zhimei Luo Subject: Re: FW: Distribution Transformer loading 

Jerry.Thank you for a most interesting submission. In the analysis of watts loss versus load that you and Phil Hopkinson develop

2011 showed that above a 60% load factor, the lower conductor losses for silicon steel units resulted in lower total losses. Navigant, I suggested they look at evaluating efficiency at two points, 50% and something higher like 80%. 

What PG&E is saying is that they are going to design their unit selections to -- essentially -- rely on overloading transforme

that correct? If so, neglecting the issue of higher-load-factor efficiency should be reconsidered by the rulemaking team.
Thanks. Very interesting.

JerryJerry W. SchoenPrincipal EngineerProduct Development & Applications EngineeringAK Steel ResearchMiddletown, OH USA 45043-0001From: "Corkran, Jerry L" <Jerry.Corkran@CooperIndustries.com>To: "Dan Mulkey" <dhm3@pge.com>, "Phil Hopkinson" <phopkinson@hvolt.com>, "Aris Marantan" <amarantan@navigant.com>, "Katie Coughlin" <kcoughlin@<richardparkerdc@gmail.com>, "Brenda Edwards" <Brenda.Edwards@ee.doe.gov>, "Brian Coffey" <brian.coffey@navigant.com>, "Caitlin Johnson" <Caitlin.Johns

<daniel.cohen@hq.doe.gov>, "Jennifer Tiedeman" <Jennifer.Tiedeman@hq.doe.gov>, "John Cymbalsky" <john.cymbalsky@ee.doe.gov>, "Chris Bolduc" <caboldu<Jeremiah.Freeman@ee.doe.gov>, "Emily Marchetti" <Emily.Marchetti@ee.doe.gov>, "Zhimei Luo" <zhimei.luo@navigant.com>

Cc: "Puesh Kumar" <pkumar@publicpower.org>, "Alex Hofmann" <ahofmann@publicpower.org>, "Andrew Delaski" <adelaski@standardsasap.org>, "Art RoseSaint" <robert.saint@nreca.coop>, "Bob Smith" <bsmith@federalpacific.com>, "Carlos Gaytan" <carlos.gaytan@ge.com>, "Caskey, John" <john.caskey@nema.org
"Charlie Stevens" <cstephens@neea.org>, "Chris Brown" <chris.brown@cogentpowerinc.com>, "Clark Silcox" <clark.silcox@nema.org>, "Creevy, Jim" <Jim.Creev

<DYoung@energy-solution.com>, "David Flaten" <david.l.flaten@xcelenergy.com>, "Eric Peterson" <Eric.Petersen@aksteel.com>, "Gary Fernstrom" <gbf1@pge.c

<greg.coulter405@gmail.com>, "Greg Rosenquist" <GJRosenquist@lbl.gov>, "Hirsch, Bruce R" <bruce.r.hirsch@bge.com>, "James Lass" <James.Lass@cleco.co<Jerry.Corkran@CooperIndustries.com>, "Jerry Hodge" <jhodge@howard.com>, "Jerry Schoen" <jerry.schoen@aksteel.com>, "Jim Raba" <Jim.Raba@ee.doe.go

<jmauer@standardsasap.org>, "John Rossetti" <jrossetti@mlgw.org>, "Ken Winder" <kwinder@mleainc.com>, "Mahesh P. Sampat" <maheshsampat@bellsouth.n<matthew.nardotti@navigant.com>, "Maxine Savitz" <maxinesavitz@aol.com>, "Meg Waltner" <mwaltner@nrdc.org>, "Michael Hyland" <mhyland@appanet.org>, 

<mrivest@navigant.com>, "Millure, Dave" <dave.millure@metglas.com>, "Pam Costello" <pamela.costello@navigant.com>, "Phil Harter" <phil@pjharter.com>, "Po

<Raymond.Polinski@atimetals.com>, "Rick Anderson" <rick.anderson@faypwc.com>, "Rob Greeson" <rgreeson@federalpacific.com>, "Robert Berman" <bermane

Buskirk" <Robert.VanBuskirk@ee.doe.gov>, "Robin Roy" <rroy@nrdc.org>, "Ryan, Paul" <Paul.Ryan@hitmet.com>, "Scott Beck" <ScottB@lvmetals.com>, "Simm<chuck.simmons@pgnmail.com>, "Steve Nadel" <snadel@aceee.org>, "Steve Rosenstock" <srosenstock@eei.org>, "Ted Johnstone" <ted.johnstone@cogentpow<tpetrosino@carolina.rr.com>, "Tim Ballo" <tballo@earthjustice.org>, "Tom Eckman" <Teckman@nwcouncil.org>, "Wes Patterson" <wes.patterson@us.abb.com>Date: 12/13/2011 03:30 PMSubject: FW: Distribution Transformer loadingDan Mulkey and Phil Hopkinson – the attached loading data and the explanation of how PG&E loads their new transformers at a targe

very factual and the most accurate explanation I have heard about how the utilities load their new transformers. We have all heard t

appears to be an example of a smart customer using the latest technology to lead the way on efficient use of new transformers.

For the 30 year time frame that is being considered for the DOE transformer efficiency rules, it seems logical that most utilities will ad

being used by PG&E to size the transformers and that a loading target similar to the 70% loading target used by PG&E will be adopted 

expected to result in load levels much higher than the 25% to 40% loads used by the DOE to calculate the pay backs for the various lo

question is what loading will be used on new transformers to be installed and not what loading exists on some unit installed long befo

Dan – Are you available to answer emails if the DOE WG has additional questions?Members of the DOE WG who are utility employees: Please comment about the practice that PGE is using to load their new transform

currently do to size transformers and what will your company do in the future to efficiently load the new transformers installed on yo

Members of the DOE and Navigant who are involved in the evaluations of the transformer designs: Please comment ‐ Would the DOE 

higher load factor in the DOE payback calculations? Based on the 70% load factor targeted by PG&E for 6 million customers, it seem

results are not accurate and that they should be revised to some load factor that reflects the latest technology that the utilities will ro

future 30 year time frame being considered.

Regards,

Jerry Corkran

From: Mulkey, Dan [mailto:DHM3@pge.com] 
Sent: Tuesday, December 13, 2011 1:42 PM

To: Phil HopkinsonCc: Corkran, Jerry L; Meyers, Aaron; Trujillo, AntonioSubject: RE: Distribution Transformer loading

Phil:It is good to hear from you again as I missed attending the last IEEE Transformers Committee Meetings in Boston.You have asked about load cycles at Pacific Gas & Electric and in fact we have public information that is readily available on our we

5.1 million meters on the PG&E system. The average data from test meters for each rate class from residential to commercial and i

basis for all 8760 hours in a year. Multiple years of data are available on the public website. The attached EXCEL spreadsheet is an 

rate classes are defined in the second attachment.

This data is not organized by transformer type but there are a number of factors that are significant to understanding the displays:1. The summary data by rate class is shown at the very bottom of the spreadsheet.2. A snapshot of the summary data is shown below:3.4. The hourly readings are the kWHrs consumed which is also the average kW load during that hour.5. Rate class E1 is the most abundant class. I estimate that it accounts for approximately 80% of the meters.6. Rate class E7 is also residential but is Time of Use service, and probably accounts for ~5% of the meters. This class is most often 

people can shift their energy consumption to off‐peak times.
7. The various other rate classes are also defined in attachment 2.

8. The yearly load factor is equal to the average load divided by the max load.9. For PG&E the average transformer is loaded to approximately 70% of nameplate. While the peak loads are normally within the 

peak loads will often exceed the nameplate rating of the transformer.

10. It is usually the physical location and grouping of the customer service points that determines the needed transformer.11. For most transformer installations the limiting factor is usually the voltage or flicker drop rather than the kVA size of the transfor12. A given transformer can be placed into service for a wide variety of loads. For instance, the same 25 kVA single‐phase pad‐moun

everything from a single signal light, to a single isolated residential customer, to fifteen or so residential customers in a subdivision in 

13. While the average distribution transformer serves 5 customers, the range is from one to several hundred.14. PG&E attempts to take advantage of the full capability of our transformers to achieve favorable economics for our ratepayersI hope that this explanation helps.Best regards,Dan MulkeySr Consulting Electrical EngineerDHM3@PGE.COM415‐973‐4699 office415‐264‐9260 cell[attachment "Electric Rate Schedules.xls" deleted by Jerry W Schoen/AKSTEEL] [attachment "2006 Load Profile.xls" 

Schoen/AKSTEEL]

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