Salt Lake County Electrical Plan Task Force

October 29, 2009

Stan SpencerCapital Investment Manager

Rocky Mountain Power

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– E = IR

Voltage (volts) = Current (amps) X Resistance (olms)

– P = IE

Power (volt-amperes) = Current (amps) X Voltage (volts)

Power (volt-amperes) has two components:

Watts

Vars

Voltage & Power Equations

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– Voltage is a measure of electrical “pressure.”

Think of voltage as similar to water pressure in a hose.

– Current is the movement of electrons through a conductor, measured in amperes or amps.

Current is analogous to water flow in a hose.

Voltage & Current

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– The basic unit of measure for power is the watt (W)

1,000 watts = 1 kilowatt = 1 kW

1,000,000 watts = 1 megawatt = 1 MW

– The maximum amount of power a transmission line can carry is referred to as capacity.

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Power (Demand)

– Energy is power multiplied by time.

In the electric utility industry energy represents the amount of power used or transmitted over a given period of time.

The basic unit of measure for electrical energy is the watt-hour.

1,000 watt-hours = 1 kilowatt-hour = 1 kWh

1,000,000 watt-hours = 1 megawatt-hour = 1 MWh

Energy

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– An electrical system is designed to provide two physical quantities:

Capacity - Demand (MW)

Energy (MWh)

– Capacity describes the maximum amount of electricity a line is capable of carrying at any instant.

– Energy describes the flow of power over a period of time.

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Capacity (Demand) versus Energy

– Your power bill at home is based on energy usage in kilowatt-hours (kWh).

– A 100 watt light bulb operated for 10 hours uses 1,000 watt-hours or 1 kWh. That would cost about 8 cents.

In 1886 Park City electric customers paid $2 per light bulb each month for electricity. That would cost $166 per month for a typical home with 83 light bulbs.

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Capacity (Demand) versus Energy

– Draw a line across a highway.

– In one direction, only 1 car can cross this line at a time. So the capacity of the highway at any instant is 1 car.

– This is like the capacity of a wire measured in kilowatts.

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Highway Analogy

– Now if we add time to the equation and a total of 500 cars can cross the line in an hour, we can say we have accommodated 500 car-hours.

– If 500 cars per hour cross the line for 2 hours we have 1,000 car-hours.

– This is analogous to kilowatt-hours of energy.

– When more people need to travel the highway we must increase the number of lanes to accommodate additional traffic = $$$.

Highway Analogy

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– As peak load grows there are 3 options

Increase system capacity to provide more power

New lines

Additional power generation

Decrease load during peak hours so less capacity is needed. This is called demand response.

Decrease load via energy efficiency.

– Rocky Mountain Power anticipates using all three options.

Load Growth

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Power Delivery

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– Assume a 10 MW load to be served

– Assume 397.5 ACSR conductor

– Assume a voltage drop from 1.0 to .95 pu

Voltage Distance

12.5 <2 miles

34.5 11 miles

46.0 20 miles

69.0 45 miles

138 >500 miles

345 unlimited

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Load versus Distance

– Assume a 397 ACSR conductor – 550 amps

Voltage Capacity cost/mile (oh) 12.5 11.9 MVA $300,00034.5 32.9 MVA $350,00069.0 65.7 MVA $500,000138 131.5 MVA $550,000345 328.7 MVA $900,000

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Capacity versus Cost

– Energy is transmitted via high voltage lines (230kv, 345kv, 500kv) from the power generator to the “city gate.”

– High voltage is used for long distance, bulk energy transmission.

– High voltage transmission lines are to electricity as an interstate freeway is to cars. There are few off-ramps or exits.

High Voltage Transmission

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– Sub-transmission voltage – 46 kilovolt to 161 kilovolt.

– Used to transmit energy between substations.

– Sub-transmission = state highway or arterial road

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Sub-Transmission Lines

– Distribution voltages range from 7.2 kilovolt to 34.5 kilovolt.

– These lines deliver electricity to your home.

– Distribution line = residential street

– Service drop = driveway

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Distribution Voltage

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Typical Line Structures

– A substation is used to transform or change voltage levels and contain equipment to protect and control power lines.

– Substations can contain the following:

Transformers

Switches

Circuit breakers

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Substations

– Think of a high voltage substation as an on-ramp or off-ramp from an interstate or an intersection connecting an arterial to a collector road.

– Generally power flows from a high voltage substation to a local substation; then to a distribution substation.

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Substations

– Using the highway analogy, electricity travels through lines and substations in the same way a commuter might go home from work.

First the commuter leaves the interstate by way of an off-ramp or high voltage substation.

Then high voltage moves down a smaller state highway, leaving the highway to a major intersection or local sub-transmission substation onto a city street.

Next it turns off the city street via a minor intersection or distribution substation into a subdivision.

Finally the commuter turns into the driveway via a pole or pad mount transformer.

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Highway Analogy

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SALT LAKE CITY VICINITYTRANSMISSION LINES

Lake Point

Par rish

Centervi lle

Wood Cross

North Sal t LakeCudahy

Rose ParkNorthwestGrow

Terminal

Lake Park

Cente nnia l

Ridgeland

Redwood

ParkwayDecker Lake

Midval ley

C annonKensington

13th South

6th South

Mort on Ct.Snarr

J ordan

5t h West 3rd West

Wes t TempleBrunswick

McClelland

North eastUnivers ityResearch

S outhwes tSoutheast

Oakland

E migration

ProposedHogle Sub Site.New Su b in 2009.

Parleys

Olympus

Cast o

Hol laday

Val ley Center

CottonwoodEast M il lcreek

Hammer

Meadowbrook

Granger

Hunter

KearnsTaylorsvi1le

Hoggard

Welby

West Jordan

South Park

Midvale Union

90th South

Altaview

Quarry

Butlerv ille

Sandy

Dimple Del l

Bingham

Oquirrh

Lark

BangerterBluffda le

Draper

118thSouth

Dumas

SouthM ountain

Camp Wi lliams

Capi tolNorth Bench

Medical

Gadsby

Orange

Riter

Salt lake ValleyArea Map

Proposed70th SouthNew 138-12.5 kV, 30 M VA Subst ationin 2005

S. SmithArea PlanningHogle Area Map11/8/04

Jordan Park

Proposed Copper Hil lsSub s ite. New Sub in 200 8

UG Line

SouthJordan

Sunrise

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138 kV Lines46 kV LinesMain StreetsCompany Owned Subs

Other Ownership

Circuit BreakersAir Break Switches

Northeast - Install 2nd 46-12.5 kV XFMRand 4.2 kV to 12.5 kV Conversion

2008 Summer

Stein Sandber g Area Plann ing EngineerDr awn by S. S mith P lanning Technologi esNortheas t - 2nd 46-12.5 kV XFMR ARE A MAP.cdr

8/16/2006

I-1

5

300

WE

ST

500

EAS

T

700

EA

ST

300

EA

ST

900

EA

ST

1100

EA

ST

190

0 E

AS

T

NORT H TEM PLE

S OUTH TEMP LE

2 00 SOUTH

4 00 SOUTH

6 00 SOUTH

600 NORTH

SU NNYS IDE

500 SOUT H

8 00 SOUTH

9 00 SOUTH

1 300 S OUTH

1 700 S OUTH

130

0 E

AS

T

MA

IN S

TR

EE

T

STA

TE

STR

EE

T

1.6

8 m

i50

0 A

AC

1.07 m i500 A A C

0.2 7 mi

500 A AC

1.59 m i500 A A C

1 .04 mi5 00 A AC

0.6 3mi0.79mi

1557 A CSR

0.33 mi 1.1 mi500 AAC

0.17 mi150 0 AL UG

0.91 mi795 A AC

1.1 m i1020 ACCC

1.05 mi795 AAC

0.8 mi795 A A C0.65 mi

795 A AC

1.4 mi155 7ACS R

0.9 mi795 A AC

2.6 mi795 A AC

2.6 m i795 A AC

1.1 mi795 AAC

0 .53 mi3 97 ACS R

0.2 mi397 A CSR

Capitol

Nor th Bench

Wes t Temple3rd West5th West

Northeast

Brunswick

13thSouth Kensington

Emigration

UniversityR esearch

Medical

M edical

N orth Tap

H ogle

6th South

Morton Court

Snarr

McClelland

Rosepark Northwest

Jordan

To Gadsby

To Gadsby

Gadsby

To MidValley

To Southeast To Southeast

To Southeast

To Cottonwood

Ma y

Tesoro

U PRR

Ref.EIMCO

Eva ns & Suthe rlan dVA Hosp ital

S tarF ire

EIM CO

AMFPor tland

n.o.n.o.

n.o.

n.o.

Remove

46-4.2 kV, 5 MVAX FMR #2 & C onvert

4.2 kV to 1 2.5 kV

Install 2nd46-12.5 kV

25 MVA XFMR

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