1. Oncor Electric Delivery Study on Residential Electric Vehicle Charging SWEDE Conference 2012 Ron Shipman

2. 1 Oncor Electric Delivery Introduction Impact of EV chargers on our system? Problems? Severity? Required Actions?

3. 2 Oncor Electric Delivery Selection of Study Sites Voltage (kV) Peak Season AreaYear Built Construction Characteristics 12.5SummerFort Worth1965Overhead (OH) w/ secondary 13.2SummerDallas1965OH parallel transformers w/ secondary 12.5SummerFort Worth1976Underground (UG) w/o secondary 12.5WinterPlano1979UG w/ secondary (no flicker consideration) 24.9SummerRound Rock2006UG w/ secondary

4. 3 Oncor Electric Delivery Study Parameters Modeled Distribution System Coincident Peak AMS Data Simulated Chargers  Level 2 Charging  Penetration Levels  Multiple Scenarios

5. 4 Oncor Electric Delivery CYME Subdivision Modeling

6. 5 Oncor Electric Delivery CYME Subdivision Modeling (cont’d) Maximum local transformer impedance Minimum service size Modeled Triplex

7. 6 Oncor Electric Delivery AMS Generated 24-Hour Load Profile

8. 7 Oncor Electric Delivery Results Fuse Loading Primary Cable Loading Transformer Loading Secondary Cable Loading Service Cable Loading Voltage Drop Localized Issues

9. 8 Oncor Electric Delivery Locations EV and EVGO Requested 2011 – 157 Locations 2012 - 25 Locations to Date Addressed (2) Transformers Addressed (1) Secondary Cable Installed 19 EVGO Locations

10. 9 Oncor Electric Delivery Questions?