Network InitiativesDiscussion Topic

Community Insights Conference

August 20-22, 2014

Vail, CO

2014 Electric T&D Benchmarking

Agenda

◼ Introduction Purpose of this Discussion Topic Schedule

◼ Background – Secondary Networks Secondary Networks Secondary Network History Current Status

◼ Results Existing networks of participating companies Future Plans – expand, contract, stay the same?

◼ Discussion by participating companies Oncor …

◼ Wrap-up

2

Introduction

• Many utilities have underground network distribution systems serving center-city areas with mostly high density loads and a few smaller customers.

• Many of these systems were originally established in the 1920’s; many of the components are approaching end-of-life.

• The character and design of these systems are essentially unchanged since they were established

• Is it time to change to a more modern design, or is the original design, with technological updates, still the best solution?

3

Detailed Discussion Topic Process

4

Primary Purpose•Plan 2014 Program•Determine Discussion Topics

•Review Questionnaire

Deliverables•Discussion Topics to pursue

•Draft Questionnaire

Deliverables•Schedule of events

• Interview questions

• Identify questions in core questionnaire that provide information

•Plan analysis•Deliverables expected

Primary Purpose•Flesh out Discussion Topic and expectations

Leader’s Conference

Discussion Topic Plan

Webinar: Set Plan

Primary Purpose•Discussion groups on Discussion Topics

•Review analysis so far

Actions/Deliverables•Group Discussions•Analysis and synthesis of data

•Presentations

Primary Purpose•Share learning

Actions/Deliverables•Presentations by stand-out companies

•Analysis/synthesis of data•Discussion groups•Action Steps •Using the analysis template

Review Meeting

Insights ConferenceOn-site

Presentations

Primary Purpose•Review Discussion Topic Plan for alignment with utility expectations

Webinar: Review Plan

Primary Purpose•Run one webinar that brings together subject matter experts on the topic and allows them to share practices and insights

Discussion Webinars

What is an “Underground Secondary Network”?

◼ Many utilities have underground network distribution systems serving center-city areas with mostly high density loads and a few smaller customers. In these areas, it is not practical to use overhead distribution systems due

to clearance problems with high-rise buildings coupled with narrow sidewalks and streets.

In many cases, local authorities have mandated that all utilities be placed underground.

◼ Though they may differ in voltage, capacity and redundancy, these systems are similar in the following ways: They use multiple primary circuits, paralleled on the secondary side. Primary circuits are protected by a breaker at the source, and by

secondary breakers, known as “network protectors”, at each transformer, relayed to open for a fault on the primary circuit (reverse power flow), and to automatically close when conditions are such that forward power flow will occur when the primary circuit is restored.

5

What is an “Underground Secondary Network”? (cont’d)

The primary circuits are paralleled with one or more transformers on different primary circuits in the same underground vault(s), and cables in the streets paralleling multiple vaults (street grid).

In this way, large loads can be served by one or more transformers at the building site, augmented by power served from the street grid in the event of the failure of a primary circuit.

Very large loads are served by “spot networks”, individual installations of several transformers, paralleled as in a normal secondary network, but not connected to the grid; most of these are at 480v, 4kv, or higher voltages to accommodate the customer’s needs.

Small loads (store fronts, parking lots, signal lights, etc) can be served by connecting only to the street grid without the necessity of installing a transformer.

Street grids are normally grounded wye 125/216v to allow single phase service to small loads.

6

Secondary Network Simplified Schematic

7

Second Illustration of Network Physical Layout from ConEd

8

Secondary Network History*

• The first “modern” secondary network, using network protectors relayed to open and close automatically, was put in service in New York City in 1922 by the United Electric Light & Power Company.

• By 1925, the secondary network had become an accepted way of serving combined power & lighting load, with 6 networks serving a total of 27.5MW

• This type of system gained rapid acceptance, and by 1952, 82 companies operated 414 networks.

• In 1974, 315 US companies used the low-voltage network system. Today's 208Y/120 V network grid systems are very similar in configuration and basic operation to the first systems.

• Today, there are over 350 cities, throughout the world, operating low voltage network systems.

9

* Information on this page from “A History of Underground Secondary AC Networks”, Robert J. Landman, H&L Instruments, L.L.C., IEEE PES, Life Senior Member, available at http://ieee-nh.org/Docs/2010-05-BL.pdf

Network Characteristics Of Participants

◼ Description of Underground Network System Age Characteristics

• Number of Customers• Load served• Number of primary circuits and voltage• Secondary voltage(s)• Physical area (square miles)

× Is the area exclusively network or are there other customers? Contingency design (first, second, or other)

◼ Current State of Network System Are new loads served from the network system, or in some other way? Have network protectors been retrofitted with solid state relays? Describe remote monitoring and control. Do you have any issues maintaining cable splicing expertise? Have you expanded or reduced your underground network system area in the

last several years? What level of new customer growth are you seeing in your network area?

10

Results – Existing Networks At Participating Companies

CompanyNetwork

Age CharacteristicsContingency

Design New Loads?Solid State

Relays?Remote

Monitoring?Problems with cable splicing?

Expanding or Reducing? Growth Rate

Austin Energy  

125/216 grid,625 xfmrs spot networks n-1

all on network, grid or spot in process  

replacing lead with eppr expanding high

BC Hydro 55 yrs120/208 grid, 347/600 v spots     yes  

replacing failed pilc with xlp  

growing, don't know rate

CenterPoint 80-90 yrs120/208 grid, 64 spots n-1

only <300kW, no spots some

spots, not grid no no new spots

heavy, new loads served w/o spots

Exelon BGE 80 yrs120/208 grid, spot networks  

try to move new loads to radial

started this year  

replace failures on pilc with epr

reducing by moving new development off grid  

KCPL

original network 90 yrs, rebuilt 60 yrs ago

611 cust,48 MVA, 12 fdrs n-1

only on network if capacity exists yes yes no no none

Oncor 1920's

120/208 grid, spot networks, 1130 xfmrs n-2   yes   no    

Westar Topeka 80 yrs

255 cust,15 MVA, 13 fdrs n-1

some from network, large not. yes

no, but adding

Yes, added training no none

Westar Wichita 80 yrs

256 cust,15 MVA, 13 fdrs n-2 network yes

no, but adding

Yes, added training no none

11

Summary of Network Characteristics

12

• All are at least 50 years old, most 80-90 years• All have ~120/208 v grids, plus spot networks• A significant percentage are making an effort to serve new, large loads in

some other way• All either have, or are in the process of installing solid-state relays• Little remote monitoring• Several are in some stage of converting PILC cable to some type of solid

dielectric (EPR or XLP)

Summary of Future of Networks

Future of Underground Network System◼ What are future plans for your underground network system?

Expand, contract, stay the same? Most staying the same Continue to serve new customers from the network, or serve in some other

way, to let network load diminish until it becomes practical to eliminate the network. Many are only serving small loads from the grid, no new spots

If you haven’t already done so, retrofit network with solid-state relays and monitoring and control. All either have, or are in process• if you have already retrofitted, what was the business case to justify the

retrofit? Business case mentioned was to do during normal protector overhaul.

Continue to use paper insulated lead covered cable, or transition to another type of cable. A few are replacing failed PILC with solid dielectric, one transitioning.• If transition, what are the details and justification for your transition• Are you doing anything to maintain paper insulated cable splicing skills? 2 companies

added training, those replacing failed cable are using premade splices.

13

Participant Input

• Oncor – Jesse Medlock• Others…

14

Wrap-up

• There are a lot of Underground Secondary Network systems out there, many are approaching 100 years old.

• Several of our participants are moving away at least from new spot networks, but they recognize that the lower voltage grid will be around for many years.

• Use of solid-state relays is predominant and practical, since network protectors must be overhauled on a regular basis.

• There is some use of the communication and monitoring capabilities of the newer relays.

• A significant number of companies are not installing new Paper Insulated Lead Covered cable, but using solid dielectric cable to replaced failed PILC, but only one is changing out all PILC.

• It is difficult to maintain PILC splicing skills if you don’t have a significant amount of the cable

15

Thank you for your Input and Participation!

16

Corporate Offices

California

400 Continental Blvd. Suite 600El Segundo, CA 90245(310) 426-2790

Maryland

3 Bethesda Metro Center Suite 700Bethesda, MD 20814(301) 961-1505

Ken Buckstaff Ken.Buckstaff@1QConsulting.com310-922-0783

Tim SxybalskiTim.Szybalski@1QConsulting.com925-878-5066

New York | Texas | Wyoming| Wisconsin

Debi McLain Debi.McLain@1QConsulting.com760-272-7277

Dave CanonDave.Canon@1QConsulting.com817-980-7909

Your Presenters

First Quartile Consulting is a utility-focused consultancy providing a full range of consulting services including continuous process improvement, change management, benchmarking and more. You can count on a proven process that assesses and optimizes your resources, processes, leadership management and technology to align your business needs with your customer’s needs.

Visit us at www.1stquartileconsulting.com | Follow our updates on LinkedIn

About 1QC

Satellite Offices

Dave CarterDavid.Carter@1QConsulting.com414-881-8641