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

Sent: Wednesday, November 02, 2011 3:02 PM 

To: Rosenstock, Steven; Richard Parker 

Cc: Caitlin Johnson; rick.anderson@faypwc.com; tballo@earthjustice.org; ScottB@lvmetals.com; 

john.caskey@nema.org; john.cymbalsky@ee.doe.gov; adelaski@standardsasap.org; 

Teckman@nwcouncil.org; gbf1@pge.com; carlos.gaytan@ge.com; rgreeson@federalpacific.com; 

bruce.r.hirsch@bge.com; mhyland@appanet.org; dave.millure@metglas.com; Nadel, Steve; 

wes.patterson@us.abb.com; Eric.Petersen@aksteel.com; Raymond.Polinski@atimetals.com; 

rroy@nrdc.org; robert.saint@nreca.coop; chuck.simmons@pgnmail.com; mark.stoering@xcelenergy.com; 

cabolduc@lbl.gov; kcoughlin@lbl.gov; Brian Coffey; gjrosenquist@lbl.gov; Michael Rivest; John Rossetti; 

Jerry Hodge; jrossetti@mlgw.org; Jim.creevy@nema.org; Meyers, Aaron; Daniel.Cohen@hq.doe.gov; 

jmauer@standardsasap.org; greg.coulter405@gmail.com; bsmith@federalpacific.com; 

pkumar@publicpower.org; Trujillo, Antonio; Phil Hopkinson; ahofmann@publicpower.org; 

BermanEconomics@gmail.com; Paul.Ryan@hitmet.com; jerry.schoen@aksteel.com; mwaltner@nrdc.org; 

kwinder@mleainc.com; chad.kennedy@us.schneider-electric.com; Kampa, Michael; Marusinec, Richard M 

Subject: RE: Impact of Electric Vehicle battery charging on distribution transformers 

Steve – Can you supply the reference data for the papers mentioned.   

The working group members are urged to read the paper before deciding on the significance of the

added loads being discussed.   The existing auto and light truck batteries range from 6 kilowatt‐hours

to 35 kilowatt‐hours of energy capacity.   The paper listed 2.5 kVA as the typical evening peak

residential load without the electric vehicle charging load.  The plug in vehicles have the option of fast

charging in 1 hour and a slow change in about 6 hours.  Smart charging may help to avoid overloading

the transformers, but it does not reduce the added load on the electrical systems required to charge

the batteries.  Charging electrical vehicles is expected to increase the residential load much more the

reductions in consumption due to efficiency improvements which Steve listed below.

The referenced paper on electrical vehicles does not state this, but it seems likely that the batteries on

electric cars will continue to increase in kilowatt‐ hour capacity  when  plug‐in electric cars larger than

the Chevy Volt are produced.

If the added load for plug‐in electric cars results in an increase from the 50% average RMS to a higher

load such as 70% of the transformer rated kVA, it would have a very significant effect on the

transformer designs that would best fit the anticipated load levels.  Because the DOE study focuses on

the next 30 years of service for the transformers being considered, it seems likely that the loads will

be higher than 50% with the addition of electric cars.  We know that some areas presently have higher

loads than 50%, because we all received Kenneth Winder’s summary for the North Carolina Coop that

currently has a 70% average load for their residential transformers.

Jerry Corkran

From: Rosenstock, Steven [mailto:SRosenstock@eei.org] 

Sent: Tuesday, November 01, 2011 8:53 AM 

To: Corkran, Jerry L; Richard Parker 

Cc: Caitlin Johnson; rick.anderson@faypwc.com; tballo@earthjustice.org; ScottB@lvmetals.com; 

john.caskey@nema.org; john.cymbalsky@ee.doe.gov; adelaski@standardsasap.org; 
Teckman@nwcouncil.org; gbf1@pge.com; carlos.gaytan@ge.com; rgreeson@federalpacific.com; 

bruce.r.hirsch@bge.com; mhyland@appanet.org; dave.millure@metglas.com; Nadel, Steve; 

wes.patterson@us.abb.com; Eric.Petersen@aksteel.com; Raymond.Polinski@atimetals.com; 

rroy@nrdc.org; robert.saint@nreca.coop; chuck.simmons@pgnmail.com; mark.stoering@xcelenergy.com; 

cabolduc@lbl.gov; kcoughlin@lbl.gov; Brian Coffey; gjrosenquist@lbl.gov; Michael Rivest; Jerry Hodge; 

jrossetti@mlgw.org; Jim.creevy@nema.org; Meyers, Aaron; Daniel.Cohen@hq.doe.gov; 

jmauer@standardsasap.org; greg.coulter405@gmail.com; bsmith@federalpacific.com; 

pkumar@publicpower.org; Trujillo, Antonio; Phil Hopkinson; ahofmann@publicpower.org; 

BermanEconomics@gmail.com; Paul.Ryan@hitmet.com; jerry.schoen@aksteel.com; mwaltner@nrdc.org; 

kwinder@mleainc.com; chad.kennedy@us.schneider-electric.com; Kampa, Michael; Marusinec, Richard M 

Subject: RE: Impact of Electric Vehicle battery charging on distribution transformers 

Greetings! 

As a response, I would ask that DOE and other researchers review the several papers that have been published by the 

Electric Power Research Institute on electric vehicle charging, with typical charging profiles showing very little 

charging at 5 PM (due to smart meters, smart chargers, EV or Time of Use rates that encourage off-peak charging or 

charging at times with minimal impacts on transformers). EPRI is also doing a study on grid impacts using field 

data and actual vehicles. 

Also, please also consider that DOE has increased efficiency for all major home appliances over the past 10 years. 

The Energy Star program has helped to make other appliances (the ones with no federal efficiency standards) more 

efficient. For example, a recent final rule mandated by DOE will go into effect on 1/1/2015 and will require new 

central air conditioners and heat pumps to be 14 SEER (in most areas of the country), which will replace the 10 

SEER units that were bought between 1992 and 2006. In addition, central units purchased in the Southwest states 

will also have EER mandates, which will reduce peak demands. Standards for dishwashers, clothes waters, water 

heaters, room air conditioners, and refrigerators have also been recently increased, with effective dates in the 2014-

2015 time period, which will also help reduce demands. 

Steve Rosenstock 

EEI 

-----Original Message----- 

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

Sent: Mon 10/31/2011 9:54 PM 

To: Richard Parker 

Cc: Caitlin Johnson; rick.anderson@faypwc.com; tballo@earthjustice.org; ScottB@lvmetals.com; 

john.caskey@nema.org; john.cymbalsky@ee.doe.gov; adelaski@standardsasap.org; Teckman@nwcouncil.org; 

gbf1@pge.com; carlos.gaytan@ge.com; rgreeson@federalpacific.com; bruce.r.hirsch@bge.com; 

mhyland@appanet.org; dave.millure@metglas.com; Nadel, Steve; wes.patterson@us.abb.com; 

Eric.Petersen@aksteel.com; Raymond.Polinski@atimetals.com; rroy@nrdc.org; robert.saint@nreca.coop; 

chuck.simmons@pgnmail.com; mark.stoering@xcelenergy.com; cabolduc@lbl.gov; kcoughlin@lbl.gov; Brian 

Coffey; gjrosenquist@lbl.gov; Rosenstock, Steven; Michael Rivest; Jerry Hodge; jrossetti@mlgw.org; 

Jim.creevy@nema.org; Meyers, Aaron; Daniel.Cohen@hq.doe.gov; jmauer@standardsasap.org; 

greg.coulter405@gmail.com; bsmith@federalpacific.com; pkumar@publicpower.org; Trujillo, Antonio; Phil 

Hopkinson; ahofmann@publicpower.org; BermanEconomics@gmail.com; Paul.Ryan@hitmet.com; 

jerry.schoen@aksteel.com; mwaltner@nrdc.org; kwinder@mleainc.com; chad.kennedy@us.schneider-electric.com; 

Kampa, Michael; Marusinec, Richard M 

Subject: FW: Impact of Electric Vehicle battery charging on distribution transformers 

Mr. Parker, 
 Two months age at the first DOE working group meeting, we requested that the added load from 

the addition of plug-in electric autos be analyzed by the DOE to determine the added load that could be expected 

over the interval the 30 year average life and 60 year maximum interval the DOE was considering for the efficiency 

analysis. So far we have not received any information. The technical paper listed below provides some insight. 

Also the paper has a list of technical references that may also provide information. The paper is addressed to 

consider the loss of life due to the overloads expected to exist when the owners of plug in electric autos arrive home 

from work and plug them in at 5 PM to recharge the batteries. The paper predicts over loading on the distribution 

transformer serving the homes studied. 

Jerry Corkran 

The impact of Electric Vehicle battery charging on distribution transformers 

ABSTRACT 

Electric Vehicles (EV) and Plug-in Hybrid Electric Vehicles (PHEV) have a limited share of the current market. 

However, it is widely expected that the situation will change in the near future and the penetration of batteryoperated vehicles will increase significantly. This paper addresses the impact of the mass operation and electricity 

consumption of EVs and PHEVs on the distribution utility and more specifically on distribution transformers. The 

charging effect of various types of EV batteries on the life of distribution transformers is analyzed. A typical annual 

base-load on the distribution transformer is considered and compared with different battery charging load scenarios. 

Simulation results show that distributing the load profile of the battery charging helps to decrease the distribution 

transformer loss of life. In addition, power management of the EV and PHEV battery charging and the interface with 

the Smart-Grid is explained. 

http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=5744627