From: Robert Berman [mailto:bermaneconomics@gmail.com]

Sent: Tuesday, December 13, 2011 10:24 PM

To: Corkran, Jerry L

Cc: jerry.schoen@aksteel.com; Andrew Delaski; Alex Hofmann; Aris Marantan; Art Rosenfeld; Robert

Berman; Brenda Edwards; Brian Coffey; Hirsch, Bruce R; Bob Smith; Chris Bolduc; Caitlin Johnson; Carlos

Gaytan; Charlie Drexler; Chris Brown; Simmons, Chuck; Clark Silcox; Charlie Stevens; Dan Cohen; Millure,

Dave; David Flaten; Dan Mulkey; Daniel Young; Emily Ma rchetti; Eric Peterson; Gary Fernstrom; Greg

Rosenquist; Greg Coulter; James Lass; Jennifer Tied eman; Freeman, Jeremiah; Jerry Hodge; Creevy, Jim;

Jim Raba; Joanna Mauer; Caskey, John; John Cymbal sky; John Rossetti; Katie Coughlin; Ken Winder;

Mahesh P. Sampat; Matthew Nardotti; Maxine Savit z; Michael Hyland; Michael Rivest; Meg Waltner;

Pamela Costello; Ryan, Paul; Phil Harter; Phil Hopkin son; Puesh Kumar; Polins ki, Raymond; Rob Greeson;

Richard Parker; Rick Anderson; Bob Saint; Robert van Buskirk; Robin Roy; Scott Beck; Steve Nadel; Steve

Rosenstock; Tim Ballo; Tom Eckman; Ted Johnstone; Thomas Petrosino; Wes Patterson; Zhimei Luo

Subject: Re: Distribution Transformer loading



### Actually the opposite is true. With increasing emphasis on energy conservation, loads will likely

continue to fall. This is especially true if you assume that system peaks are weather driven and

transformer capacity must be there to maintain system reliability even (or especially) on hot

summer days.



## Regards,

Robert A. Berman, Principal

Berman Economics

www.BermanEconomics.com

1915 Grand Court

Vienna, VA 22182

703

‐ 281

‐ 0490

703

‐ 655

‐ 8398 (cell)

BermanEconomics@gmail.com

On Dec 13, 2011, at 9:36 PM, Corkran, Jerry L wrote:

Jerry,

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

most of the other utilities will do soon, because it is an intelligent way to use the smart meter

capabilities. It is smart not just for the transformers, but also for the cable capa cities.

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

study used for the maximum efficiency point. The 50% maximum efficiency target is wrong now for new

transformers purchased by PG&E and it is either wrong now or it will sooner or later be wrong for the

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

load which gives them maximum utilization of their equiptment. If a 70% average RMS load is the

expected target when smart meters are in widespread use, then the DOE should targe t the 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 calculations will be more accurate. If the predicted average transformer loads are

incorrect, then the payback calculations are incorrect such that they distort the actual 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 transformer evaluations used in the DOE calculations. Katie’s sample population was

10,000 transformers while the PG&E population data was 6 million transformers.



### Hello all,

Load losses are calculated based on the annual a verage of the squared load, i.e. the RMS. The

LCC analysis sums the results from a sample population of 10,000 transformers, each of which

is loaded differently, so we work w ith a distribution of RMS loadings.

The shape of this distribution is approximatel y triangular. The shape of the distribution was

developed based on an analysis of hourly building loads for several hundred commercial,

residential and i ndustrial buildings.

The building load data can give us the average load is relative to the peak load. For the

transformer analysis we also need to know what is the peak load rela tive to the transformer

capacity. In the LCC, this "peak load fact or" is also chosen from a distribution.

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

an additional parameter that scales the entire RMS load distribu tion up or down. The value of

this parameter determines the average RMS l oading, relative to transformer capacity, for the

transformer population.

Initially the Department's estimat es for the population-average RMS loading were taken from the

previous rulemaking. For the current rulemaking, the utility representatives on the committee

have provided us with data on transformer l oads, primarily for single- phase, smaller capacity

units connected to residentia l 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. No te that these design li nes also serve small

commercial and multi-family loads, but we do not have data on average loading for those

customer classes.

For the larger capacity transformers and 3-phase tr ansformers, the loading is currently set to

about 40% population-average RMS. We also do 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 judgment of the utility managers will lead them to follow the PG&E lead to

result in an electric utility industry loaded at about the 70% of full load level chosen by PG&E. Th e

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, Bruce R; Bob Smith; Chris Bolduc; Caitlin Johnson; Carlos Gaytan; Charlie Drexler;

Chris Brown; Simmons, Chuck; Clark Silcox; Charlie Stevens; Dan Cohen; Millure, Dave; David Flaten;

Dan Mulkey; Daniel Young; Emily Marchetti; Eric Pete rson; Gary Fernstrom; Greg Rosenquist; Greg

Coulter; James Lass; Jennifer Tiedeman; Freeman, Jere miah; Corkran, Jerry L; Jerry Hodge; Creevy, Jim;

Jim Raba; Joanna Mauer; Caskey, John; John Cymbal sky; John Rossetti; Katie Coughlin; Ken Winder;

Mahesh P. Sampat; Matthew Nardotti; Maxine Savitz; Michael Hyland; Michael Rivest; Meg Waltner; Pam

Costello; Ryan, Paul; Phil Harter; Phil Hopkinson; Pu esh Kumar; Polinski, Raymond; Rob Greeson; Richard

Parker; Rick Anderson; Bob Saint; Robert van Bus kirk; Robin Roy; Scott Beck; 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 ve rsus load that you and Phil

Hopkinson developed and sent out on 31 October 20 11 showed that above a 60% load factor, the lower

conductor losses for silicon steel units resulted in lower total losses. In my earlier discussions with

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 desi gn their unit selections to -- essentially -- rely on

overloading transformers during peak demand times. Is that correct? If so, neglecting the issue of higherload-factor efficiency should be reconsidered by the rulemaking team.

### <image001.gif>

Thanks. Very interesting.

Jerry

Jerry W. Schoen

Principal Engineer

Product Development & Applications Engineering

AK Steel Research

Middletown, OH USA 45043-0001

From: "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@lbl.gov >, "Richard Parker" < richardparkerdc@gmail.com >, "Brenda Edwards" < Brenda.Edwards@ee.doe.gov >, "Brian Coffey" < brian.coffey@navigant.com >, "Caitlin Johnson" < Caitlin.Johnson@navigant.com >, "Dan Cohen"

< daniel.cohen@hq.doe.gov >, "Jennifer Tiedeman" < Jennifer.Tiedeman@hq.doe.gov >, "John Cymbalsky" < john.cymbalsky@ee.doe.gov >,

"Chris Bolduc" < cabolduc@lbl.gov >, "Freeman, Jeremiah" < 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 Rosenfeld" < artrosenfeld@gmail.com >, "Bob Saint" < robert.saint@nreca.coop >, "Bob Smith"

< bsmith@federalpacific.com >, "Carlos Gaytan" < carlos.gaytan@ge.com >, "Caskey, John" < john.caskey@nema.org >, "Charlie Drexler"

< charlied@uus.org >, "Charlie Stevens" < cstephens@neea.org >, "Chris Brown" < chris.brown@cogentpowerinc.com >, "Clark Silcox"

< clark.silcox@nema.org >, "Creevy, Jim" < Jim.Creevy@nema.org >, "Daniel Young" < DYoung@energy-solution.com >, "David Flaten"

< david.l.flaten@xcelenergy.com >, "Eric Peterson" < Eric.Petersen@aksteel.com >, "Gary Fernstrom" < gbf1@pge.com >, "Greg Coulter"

< greg.coulter405@gmail.com >, "Greg Rosenquist" < GJRosenquist@lbl.gov >, "Hirsch, Bruce R" < bruce.r.hirsch@bge.com >, "James Lass"

< James.Lass@cleco.com >, "Corkran, Jerry L" < Jerry.Corkran@CooperIndustries.com >, "Jerry Hodge" < jhodge@howard.com >, "Jerry

Schoen" < jerry.schoen@aksteel.com >, "Jim Raba" < Jim.Raba@ee.doe.gov >, "Joanna Mauer" < jmauer@standardsasap.org >, "John

Rossetti" < jrossetti@mlgw.org >, "Ken Winder" < kwinder@mleainc.com >, "Mahesh P. Sampat" < maheshsampat@bellsouth.net >, "Matthew

Nardotti" < matthew.nardotti@navigant.com >, "Maxine Savitz" < maxinesavitz@aol.com >, "Meg Waltner" < mwaltner@nrdc.org >, "Michael

Hyland" < mhyland@appanet.org >, "Michael Rivest" < mrivest@navigant.com >, "Millure, Dave" < dave.millure@metglas.com >, "Pam Costello"

< pamela.costello@navigant.com >, "Phil Harter" < phil@pjharter.com >, "Polinski, Raymond" < Raymond.Polinski@atimetals.com >, "Rick

Anderson" < rick.anderson@faypwc.com >, "Rob Greeson" < rgreeson@federalpacific.com >, "Robert Berman"

< bermaneconomics@gmail.com >, "Robert van Buskirk" < Robert.VanBuskirk@ee.doe.gov >, "Robin Roy" < rroy@nrdc.org >, "Ryan, Paul"

< Paul.Ryan@hitmet.com >, "Scott Beck" < ScottB@lvmetals.com >, "Simmons, Chuck" < chuck.simmons@pgnmail.com >, "Steve Nadel"

< snadel@aceee.org >, "Steve Rosenstock" < srosenstock@eei.org >, "Ted Johnstone" < ted.johnstone@cogentpowerinc.com >, "Thomas

Petrosino" < 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 PM

Subject: FW: Distribution Transformer loading

Dan Mulkey and Phil Hopkinson

– the attached loading data and the explanation of how PG&E loads their new

transformers at a targeted 70% of the nameplate rating is very factual and the most accurate explanation I have

heard about how the utilities load their new transformers. We have all heard th e terms “Smart Grid”. This

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 adopt a similar smart process as is 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 ado pted by the utility industry. This isexpected 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 loss levels considered. The key question is what loading will be used on new transformers to

be installed and not what loading exists on some unit i nstalled long before the smart meters existed.

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 transformers. What does your company currently do to size transformers and what will your company

do in the future to efficiently load the new transformers installed on your systems?

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

comment

‐ Would the DOE and Navigant consider using a higher load factor in the DOE payback calculations?

Based on the 70% load factor targeted by PG&E for 6 million customers, it seems that the DO E study payback

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

the utilities will routinely be using based on the 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 Hopkinson

Cc: Corkran, Jerry L; Meyers, Aaron; Trujillo, Antonio

Subject: 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 website. There are approximately 5.1 million meters on the PG&E system. The average data

from test meters for each rate class from residential to commercial and industrial is dis played on an hourly basis

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

spreadsheet is an extract of the data for 2006. The 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. 

### <image002.png>

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 advantageous for homes where 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 capability of the transformer, 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 transformer.

12. A given transformer can be placed into service for a wide variety of loads. For instance, the same 25 kVA

single

‐ phase pad

‐ mount could be used to supply everything from a single signal light, to a single isolated

residential customer, to fifteen or so residential customers in a subdivision in a coastal area.

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 ratepayers

.

I hope that this explanation helps.

Best regards,

Dan Mulkey

Sr Consulting Electrical Engineer

DHM3@PGE.COM

415

‐ 973

‐ 4699 office

415

‐ 264

‐ 9260 cell[attachment "Electric Rate Schedules.xls" deleted by Jerry W Schoen/AKSTEEL] [attachment

"2006 Load Profile.xls" deleted by Jerry W Schoen/AKSTEEL]

Confidentiality Notice

This message is intended exclusively for the individual or

entity to which it is addressed and may contain privileged,

proprietary, or otherwise private information.

If you are not the named addressee, you are not authorized

to read, print, retain, copy or disseminate this message or

any part of it. If you have received this message in error,

please notify the sender immediately by e-mail and delete

all copies of the message.