ECONOMIC BENEFITS OF USING HIGH(ER) EFFICIENCY TRANSFORMERS IN LOW LOAD CONDITIONS Florida Electrical Cooperative Association Statewide Engineers Conference Clearwater, Florida June 11, 2014 David Nathasingh & Paul Ryan Metglas Inc

INTRODUCTION Transformer Efficiency Varies As a Function of Load Conditions Low No Load Loss (Core Loss) Transformers Perform Best When Loading is <50% DOE Compliant Amorphous Metal and Silicon Steel Transformers Have Different Efficiency Levels When Loading <50% *Low No Load Loss Transformers May Cost More But are More Economical to Operate in Both the Short and Long Term *Depending on specification level, first-cost can be lower or higher

Core Materials Used in High(er) Efficiency Transformers Saturation Magnetization Core Losses Silicon Steel Amorphous Metal Amorphous Metal

CASE 1 TOBACCO FARM – South Carolina Two Curing Barns Curing Period – August Thru September DOE 75 kVA Single Phase Polemount Amorphous Metal and Silicon Steel Transformers Transformers Idle for 10 months; Loaded for 2 months Average Load of Transformers <50% CASE 2 WINDFARM – California Farm With 70 Turbines 2600 kVA Generator Step Up Amorphous Metal and Silicon Steel Transformers 83% Annual Turbine/Transformer Loading ≤37.5%

DEFINITIONS DOE Transformer – Transformer manufactured to meet DOE Minimum Efficiency Standards 72CFR Designed for an average loading of 50%. Generator Step Up Transformer (GSU) – Used on Wind Farms to step up turbine voltage of 690V to 34,500V. They are sized to meet peak turbine output and NOT governed by DOE Minimum Efficiency Standards. Higher Efficiency Transformer – Transformer optimized to minimize core losses – no load losses. Efficiency higher than DOE current Standards. Capitalized Losses – Cost of losses over the life of the transformer. Total Owning Costs – Capitalized Losses + Purchase Price of Transformer. Present Value of Losses – Future cost of losses in today’s dollars.

Use Amorphous Metal and Silicon Steel Transformers Made To DOE Standards Record load Currents and Voltages For Parts of Curing Period And Idle Period Use One Curing Period Data to Calculate Losses During Entire Curing Period Use 2 Week Idle Period Data to Calculate Losses During Rest of Year CASE 1 – TOBACCO FARM Test Procedure

The efficiency levels in each TSL can be characterized as follows: Baseline is our existing required efficiency. TSL 1 represents an increase in efficiency where a diversity of electrical steels are cost-competitive and economically feasible for all design lines. (DOE settled on this) TSL 2 represents EL1 for all design lines TSL 3 represents the maximum efficiency level achievable with M3 core steel. TSL 4 represents the maximum net present value (NPV) with 7 percent discounting. TSL 5 represents EL 3 for all design lines. (Advocates wanted this) TSL 6 represents the maximum source energy savings with positive NPV with 7 % discounting. TSL 7 represents the maximum technologically feasible level.

Core Material No Load Loss (Watts) Load Loss (Watts) %IX%IRDOE Efficiency (%) Est Transformer Price ($) Amorphous Silicon Steel kVA TRANSFORMERS USED IN STUDY DOE Standard 72 CFR Average Loading 50% Minimum Efficiency 99.17%

No Load and Load Loss During Idle Time AMORPHOUS METAL TRANSFORMER

No Load and Load Loss During Idle Time SILICON STEEL TRANSFORMER

AMORPHOUS METAL TRANSFORMER No Load and Load Loss During Typical Curing Cycle

SILICON STEEL TRANSFORMER No Load and Load Loss During Typical Curing Cycle

ANNUAL LOSSES kWh CoreCoil Idle Coil Loaded Total Loss Ratio AM/SiFe AM % SiFe AM-Sw % SiFe-Sw Sw – Transformers rotated between Loads

ANNUAL LOSSES kWh CoreCoil-Idle Coil-Loaded Total Delta AM SiFe AM-Sw SiFe-Sw Sw – Transformers rotated between Loads 555 kWh 415 kWh

TOBACCO STUDY CONCLUSION DOE Amorphous Metal Transformer had 25-32% less losses over one year DOE Amorphous Transformer saves % of the total load delivered to Curing Barns Both DOE Transformers have the same efficiency at 50% Load. BUT at Loads <50%, Amorphous Transformer exhibits higher efficiency than Silicon Steel. NOTE: 50% AVG load is not realistic. DOE data indicated the national AVG to be 33%. Savings equate to about $1,500 over 30 year Transformer life. Simple Payback ~ 2.5 Years.

CASE 2 – WIND FARM Financial Analysis Amorphous Metal and Silicon Steel Transformers Designed for Lowest Total Owning Costs (TOC) Use Transformer Average Loading Data from California Wind Farm Analysis Use Average Loading of 37.5% to Calculate Economic Benefit

Source : American Wind Energy Association (AWEA) No established Wind Farms ---- Wind Maps----

Wind Power Installations Source: American Wind Energy Association (AWEA) Production Tax Credit Expired ($0.02 kWh)

690v to 34.5kV

© ABB Group Wind Energy Case Study Generation Profile Base case generation profile based on actual wind site in the United States 83% generation hours at or less than 37.5% of generation capacity It’s been reported that most wind sites operate on average at less than 50% of capacity during the year (EIA Data) 83% annual turbine output < 37.5% Buying power from the 3 times wholesale to keep Collector network energized.

SILICON STEEL kVAV1, V2No Load Load LossesAverageEffective Load Total Losses % No Load Losses(W)LoadingLosses(W)of Total (W) (%)(W) Losses 10020,81624, ,93719, ,60034,5003,96620, ,13112, ,9276, , , AMORPHOUS METAL kVAV1, V2No Load Load LossesAverageEffective Load Total Losses % No Load Losses(W)LoadingLosses(W)of Total (W) (%)(W) Losses 10022,19422, ,99217, ,60034, , ,6709, ,1212, , Data Courtesy ABB Group GENERATOR STEP UP (GSU) TRANSFORMERS USED IN STUDY

COSTS of LOSSES - Annual & PV 6% and 20 Year Life Silicon Steel Transformer Load FactorTotal Losses kWh/yrEnergy Costs ($)Present Value 10024,782217,09014,111161, ,903174,35211,333129, ,097105,9726,88879, ,89360,3853,92545, ,29137,5912,44328, ,96634,7422,25825,902 Amorphous Metal Transformer Load FactorTotal Losses kWh/yrEnergy Costs ($)Present Value 10022,949200,94613,061149, ,737155,37910,100115, ,41582,4715,36161, ,86633,8662,20125, ,0929, , , ,866 Data Courtesy ABB Group $0.065/ kWh estimated to Generate,Transmit and Distribute

FINANCIAL ANALYSIS (Average Loading %) Simple Payback Amorphous Metal Transformer Price : $38,400 Silicon Steel Transformer Price : $32,000 Price Difference : $ 6,400 Price Difference $6,400 Annual Energy Savings $1,724 – 1,821 Payback ~3.5 YRS ABB 2600 kVA GSU 2011 Pricing Present Value 6%, 20 YRS Silicon Steel COL $25,249 – 45,020 Amorphous Metal COL $ 7,130 – 28,026 Difference $19,771 – 20,896 Δ Transformer Price -$6,400 Amorphous Metal Costs $13, ,496 Less to Operate in Today’s Dollars

Wind Farm Study Conclusion Transformer Efficiency Determined by Turbine Output - Loading Profiles Show Average Loading ≤ 50%. Actual US Avg 12.5%. Low Core Loss Amorphous Metal Transformers Are More Efficient Than Silicon Steel Transformers Under These Low Load Conditions. Amorphous Metal Transformers May Have a Higher Initial Cost But Payback is ~3.5 Years. Annual savings equivalent to about 2% of expired Federal Production Tax Credit. Not Economical to Purchase ‘Off The Shelf’ Transformers When Average Loading ≤ 50%.

FINAL THOUGHTS COOPs tend to have Lower Loading profiles than MUNIs or IOUs. Higher Efficiency (Low Core Loss) transformers should be considered as part of installation mix. The Rural Utility Service (RUS) will offer 30 year to purchase Amorphous Metal transformers. Generation of Renewable Energy tend to be more expensive. Use of Higher Efficiency transfomers during distribution would improve economics. Transformer Efficiency is the starting point. Average Loading takes it to the next economic level.

Thermal Parameters During Curing Cycle

Load Current During Curing Cycle