Rocky Mountain Power Five Year Study Findings & Kick Off Meeting Attachment K Rocky Mountain Power Five Year Study Findings & Kick Off Meeting

Findings Reports Kickoff Studies Study Areas for 2016 Findings Reports Kickoff Studies

Grace Study Findings AREA PLANNER: Prepared by:

System Overview Covers 1,030 square miles Main Sources are Grace and 3 Mile Knoll, contributions from Treasureton 26 substations, 14 being customer owned Area has 161, 138 and 46 kV lines There are 14 transmission lines in/out of the area Bancroft Conda Soda Springs McCammon Lava Hot Springs Grace Arimo

Load Growth Base System Loads Growth: Projected System Loads Summer 2016: 276 MW (Industrial 80%) Winter 2016-17: 271 MW Growth: Average Summer Percentage 1.1% Average Winter Percentage 1.5% Projected System Loads Summer 2020: 289 MW Winter 2020-21: 288 MW Distribution capacity: 72 MVA Area Utilization Factor: 28%

N-0 Conditions – Replace CB’s Grace Plant Replace CB’s, 2018 CB 123 will be loaded to 132 % (3 ᶲ rating, continuous 800 Amp, 10.5 kA) CB 126 will be loaded to 132 % (3 ᶲ rating, continuous 1200 Amp, 10.5 kA) Solution: Increase both CB’s with 2000 Amp (continuous) 40 kA (interrupting) Estimated cost: $0.9m

N-0 Conditions – Replace CB’s Bancroft Replace CB’s, 2018 CB 12 will be loaded to 108 % (1 ᶲ rating, continuous 100 Amp, 2 kA) Solution: Increase both CB with at least 6 kA (interrupting) rating. Estimated cost: $100k

N-0 Conditions – Upgrade Switch Arimo Upgrade Switch, This switch lacks the full load break and line dropping capability Solution: Upgrade switch 5A at Arimo to a LO/LD capability Estimated cost: $75k

N-0 Conditions – Upgrade Switch Trail Junction Upgrade Switch, This switch lacks the full load break and line dropping capability Solution: Upgrade switch 61A at Trail Junction to a LO/LD capability Estimated cost: $75k

N-0 Conditions – Upgrade Switch Lund Tap Upgrade Switch, 42A switch at Lund Tap lacks the full load break and line dropping capability Solution: Upgrade switch 42A at Lund Tap to a LO/LD capability Estimated cost: $75k

There were no prominent N-1 conditions

Total Construction Costs Construction Item 2016 CONSTRUCTION Cost Investigate the loading discrepancy at Cove substation O&M Subtotal $0.0 2018 CONSTRUCTION Grace Plant ~ Replace CB 123 and CB 126 $900k Bancroft ~ Replace CB 12 $100k $1.0m Reliability Work Plan Projects Arimo ~ Upgrade switch to LO/LD $75k Trail Junction ~ Upgrade switch to LO/LD Lund Tap ~ Upgrade switch to LO/LD $225k TOTAL COST $1.225m

Any questions or comments?

Smithfield/Preston Study Findings AREA PLANNER: Prepared by:

System Overview Covers 450 square miles Main Sources are Treasureton, Wheelon and Bridgerland Generation: Oneida, Preston, Mink Creek and 2 customer 23 substations, 3 being customer owned Area has 230, 138 and 46 kV lines

Load Growth Base System Loads Growth: Projected System Loads Summer 2015: 238 MVA Winter 2015-16: 161 MVA Growth: Average Summer Percentage 2.0% Average Winter Percentage 2.0% Projected System Loads Summer 2020: 279 MVA Winter 2019-20: 199 MVA Distribution capacity: 180 MVA Area Utilization Factor: 79%

N-0 Conditions – Low Voltage Franklin Change No-Load Tap There is 35 miles of 1/0 and 3/0 ACSR conductor that causes voltage drop between Franklin and Downey Solution: Change the no-load tap at Franklin to tap #4 (134.5 kV) on the 46 kV system and install a 1.2 Mvar capacitor bank on 12.47 kV Downey system Estimated cost: O&M

N-0 Conditions – Bypass Hyrum Bus East Hyrum Bypass Conductor bus size is 7-#2 Cu will load to 114% (18 MVA) Solution: Connect the Hyrum City line to the western Nibley-East Hyrum line (capacity is 25 MVA) Estimated cost: $30k

N-0 Conditions – Increase Capacity Lewiston Upgrade, 2018 Lewiston transformer loads to 101% (14 MVA) Solution: Install a 22.4 MVA transformer spare equipped with an LTC Estimated cost: $700k

N-1 Conditions - Disable Auto Throwover Richmond Auto –Throwover, 2018 The loss of Franklin 138-46 kV transformer will cause Smithfield transformer to load to 106% (33 MVA), with the auto-throwover scheme on Solution: Disable the Richmond auto-throwover during the summer to prevent overload Estimated cost: N/A

N-0 Conditions – Install Cap Bank Downey Install Cap Bank, 2019 Low voltage happens on the line between Franklin and Downey substations Solution: Along with the change of the no-load tap at Franklin, a 1.2 Mvar capacitor bank installed at Downey Estimated cost: $200k

N-0 Conditions – Install Fans Weston Install Fans In summer 2013, transformer loaded to 95% of its rating (3.75 MVA). The peaks have gone down but the capacity should be raised. Solution: Install additional fans on the Weston transformer fins, to increase the rating Estimated cost: $15k

N-0 Conditions – Replace CB Green Canyon Replace CB CB L33 will be loaded to 113% (3 ᶲ rating, continuous 600 Amp, 6.3 kA) Solution: Increase CB L33 with 2000 Amp (continuous) 40 kA (interrupting) Estimated cost: $640k

N-0 Conditions – Replace CB’s Treasureton Replace CB’s CB L101 & CB L102 will be loaded to 115% (1 ᶲ rating, continuous 1600 Amp, 18 kA) & 99% (1 ᶲ rating, continuous 1200 Amp, 21 kA) Solution: Increase both CB with higher fault duties to prevent circuit breakers from failing Estimated cost: $1.3m

N-0 Conditions – Upgrade Switches Lewiston Upgrade Switches 41A & 42A switches at Lewiston lacks the full load break and line dropping capability Solution: Upgrade switch 41A & 42A at Lewiston to a LO/LD capability Estimated cost: $100k

There were no prominent N-1 conditions

Total Construction Costs Franklin ~ Low Voltage: change no-load tap O&M East Hyrum ~ Connect Hyrum City feed to Nibley-East Hyrum line $30k Subtotal 2018 CONSTRUCTION Lewiston ~ Increase Capacity $700k Richmond ~ Disable the auto-throwover during summers 2019 CONSTRUCTION Downey ~ Install 12.47 kV 1.2 Mvar capacitor bank $200k NO TIMELINE CONSTRUCTION Weston ~ Install additional fans $15k Green Canyon ~ Replace CB L33 $640k Treasureton ~ Replace CB’s L101 and CB L102 $1.3m Lewiston ~ Install LO/LD switches in place of 41A and 42A $100k $2.06m TOTAL COST $2.985m

Any questions or comments?

Price (Utah) Study Findings AREA PLANNER: Prepared by:

System Overview Covers 5,200 square miles Main Sources are Huntington and Hunter (Emery), contributions from Sunnyside gen Approximately 60 substations, 31 being customer owned Area has 345, 138, 69 and 46 kV lines

Load Growth Base System Loads Growth: Projected System Loads Summer 2015: 130 MW (Industrial 66%) Winter 2015-16: 131 MW Growth: Average Summer Percentage 1.3% Average Winter Percentage 1.1% Projected System Loads Summer 2020: 149 MW Winter 2020-21: 146 MW Distribution capacity: 107 MVA Area Utilization Factor: 50%

N-0 Conditions – Increase Capacity XFMR name Upgrade, 2017 Spanish Fork XFMR at 108% ( MVA Rating) Install a MVA pole mount substation (North Arm) Scofield Reservoir Scofield Reservoir Estimated cost: $200k

N-1 Conditions – Install Breakers Helper Install Circuit Breakers, 2018 Loss of the Carbon-Helper 138 kV line results in overloading between Price City Tap and Mill Creek Tap 46 kV line to 116% (36 MVA, emergency) Also, results in low voltage on the 46 kV system being served by Helper Solution: Place breakers on the second Carbon-Helper 138 kV line, which is normally open producing a second feed to the area. Estimated cost: $8.3m

There were no prominent N-1 conditions

Total Construction Costs Construction Item 2017 CONSTRUCTION Cost Scofield Reservoir ~ Increase capacity $200k Subtotal 2018 CONSTRUCTION Helper Substation ~ Install new 138 kV yard with Circuit Breakers $8.3m TOTAL COST $8.5m

Any questions or comments?

Study Areas for 2016 Kickoff Studies

Lakeside is to the North Tooele (Utah) Study Service Area Lakeside is to the North Dividing line is the Tooele county border Terminal & Oquirrh are the main sources for the area

Tooele (Utah) Study Info Covers 800 square miles in Tooele county. 2 sources – Terminal & Oquirrh serving 4 -138 kV lines. Approximately 32 substations, 14 are customer owned 1 Alt. (46 kV) Source at Terminal Transmission voltages 46 & 138 kV

Any questions or comments?

Southeast Utah Study Service Area Area is located in Grand and San Juan counties Pinto (via 345 kV Huntington to Four Corners), Abajo & Moab are the main sources for the area Dividing lines are counties lines & the Utah border

Southeast Utah Study Info Covers 6,500 square miles in Grand & San Juan counties Serves NTUA loads (Navajo Tribal Utility Authority) Approximately 31 substations, 14 are customer owned Transmission voltages 46, 69, 138 & 345 kV Study will concentrate mainly on the 138 kV system & below

Any questions or comments?

North Salt Lake Study Service Area Dividing line is North Temple to the South & Farmington to the North. 3 - 138 kV lines origination at Terminal 46 kV sources at Parrish, Gadsby & Jordan subs.

North Salt Lake Study Info Covers 67 square miles in southern part of Davis & north part of Salt Lake County Main sources are Terminal, Parrish, Gadsby & Jordan. Major sources include 3 - 138 kV lines originating from Terminal. Municipalities: Kaysville City & Bountiful City Approximately 29 substations, 12 are customer owned Transmission voltages 46 & 138 kV

Any questions or comments?