DOE Distribution Transformer Efficiency Regulation
Evaluation of Impact on the Industry
Carlos GaytanManager of Engineering
Distribution Transformers
April 29, 2008
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Agenda
Efficiency Calculations
Impact on Materials
Impact on Manufacturers
Impact on Customers
Customer Purchasing Practices
Outstanding Issues / Concerns
Summary and Next Steps
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Efficiency Calculations
Efficiency = Power OUT / Power IN
Where:
%EFF = Efficiency means the ratio of the useful power to the total power input; for DOE Rule it is calculated at 50% Load
kVA = Transformer Capacity in kilo Volt Ampere
NL = No Load (Core) Losses corrected to 20°C
LL = Load Losses corrected to 85°C
0.91 = Load Loss Temperature correction from 85°C to 55°C
)1000/)5.0*91.0*((5.0*
5.0**100%
2LLNLkVA
kVAEFF
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Efficiency Calculations
)/1000)]0.5 x 0.91 x LL((NL0.5 0.5/[kVA xkVA x x 100%EFF 2No Load Losses represent a critical portion of the
Transformer Efficiency
)1000/)5.0*91.0*((5.0*
5.0**100%
2LLNLkVA
kVAEFF
No Load Loss Impact25 kVA 1 Phase Designs having the same Total Losses
at 100% Load / 85°C
98.00
98.10
98.20
98.30
98.40
98.50
98.60
98.70
98.80
98.90
99.00
99.10
99.20
0 0.2 0.4 0.6 0.8 1 1.2
NL / LL Ratio (85°C)
Tr
ansf
orm
er E
ffici
ency
(%
)
Efficiency @ 100% Load / 85°C
Efficiency @ 50% Load / 55°C
DOE Minimum Efficiency
98.44%
98.91%
NL/LL=0.182
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Efficiency CalculationsExamples of No Load Loss Impact
Two 25 kVA 1-Phase Designs with Same Efficiency at 100% Load are evaluated at 50% load (DOE basis):
• Design #1: NL=75W, LL=325W, TL=400W (NL/LL=0.23)
• Design #2: NL=55W, LL=345W, TL=400W (NL/LL=0.16)
)1000/)5.0*91.0*32575((5.0*25
5.0*25*100%
2EFF
%82.98% EFF Does Not Meet DOE Rule of 98.91%
)1000/)5.0*91.0*34555((5.0*25
5.0*25*100%
2EFF
%94.98% EFF Meets DOE Rule of 98.91%
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Efficiency CalculationsLoad Loss Impact
25 kVA Single Phase Designs
97.50
97.70
97.90
98.10
98.30
98.50
98.70
98.90
99.10
99.30
99.50
Load Losses
Eff
icie
nc
y
Effic @100% & 85°C
Effic. @ 50% & 55 °C
DOE
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Loss Differential for 0.01 Percent Change in EfficiencySingle Phase 10 to 833 kVA
and Three Phase 15 to 2500 kVA
0
0.5
1
1.5
2
2.5
98.00 98.20 98.40 98.60 98.80 99.00 99.20 99.40 99.60
Efficiency
% R
educ
tion
of L
osse
s ne
eded
for
0.0
1 in
crem
ent
in
Effi
cien
cy
Delta (%) 1Ph
Delta (%) 3Ph
Efficiency CalculationsEfficiency vs Losses
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Efficiency Calculations
Around 50% of present designs available already meet the Efficiency Levels of the DOE Rule
Percent of available designs that meet DOE Rule
0
10
20
30
40
50
60
10 15 25 37.5 50 75 100 167
kVA Rating
Pe
rce
nt
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Impact on MaterialsCore Material:
• Silicon Steel – M5(12 mil), M4(11 mil), M3 and M0H (9 mil), M2(7 mil) As efficiency of material improves total market volume decreases Worldwide limited supply of Grain Oriented Silicon Steel 5-year cost increase = 65% M3, M2 or better grades will become the most popular for DOE compliance
• Amorphous Metal Supply is tight, price flat in last 5 years Not an option for a significant conversion from Silicon Steel
Conductor Material:• Copper Wire
5-year cost increase = 240% Preferred material for High Voltage Windings
• Aluminum 5-year cost increase = 20% Preferred for LV windings; limited application for HV windings
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Published Typical Losses of different Core MaterialsAt 1.5 Tesla / 60 Hz, (except for SA1 which is at 1.3 Tesla)
SA1 (Amorphous)
1 mil
M2, 7 mil M0H, 9 milM3, 9 mil
M4, 11 mil
M5 12 mil
M6, 14 mil
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1Core Material
Lo
sse
s (W
/kg
)
0.30
1.27
0.820.84
0.89
1.00
1.09
Impact on Materials
“M3 or Better” Grade Required to Meet DOE
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NIPPON STEELJapan13%
JFEJapan
9%
AK SteelUSA15%
TKES/W. Eur.12%Cogent/W. Eur.
4%
East Europe2%
Viz StalRussia
17%
AcesitaBrazil
2%
POSCOS.Korea
12%
AlleghenyUSA4% Wuhan/China
13%
EBG/India0%
Total = 2.1 Million (MT)
2007 World Installed Production of Grain Oriented Silicon Steel*
* Data Courtesy of Sumitomo Corporation
Impact on Materials
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PoscoS. Korea
23%
JFEJapan19%
TKES/ W. Eur.17%
AK SteelUSA8%
COGENTW. Eur.
1%
Nippon SCJapan32%
2007 World Installed Production of Hi B Silicon Steel*
Total = 0.64 Million (MT)* Data Courtesy of Sumitomo Corporation
Impact on Materials
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World Installed Capacity of Grain Oriented Silicon Steel*(Thousands of MT)
400 400 400 410 440
60 75 120250 250130
200
200
400
160
230
240
250
250
250
100
110
111
111
114
310
310
330
330
380
230
230
270
304
320
80
80
80
90
90
130
0
0
40
30
30
30
40
40
0
500
1000
1500
2000
2500
2004 2005 2006 2007 Proj 2008Year
Acesita
Alsco
AKS
Russia
Other European
TKES
Baoshang
Wuhan
Posco
Japan
* Data Courtesy of Sumitomo Corporation
Impact on Materials
75%+ of Growth in Capacity in Asia; intended for domestic market
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Manufacturer Key Issues:
• Amorphous Material
Possible difficulty of access to the technology; limited sourcing options
The high level of capital equipment investment required (rendering obsolete a large portion of the equipment used in the liquid-immersed industry, particularly core-cutting equipment and annealing furnaces)
• Core steel price volatility and uncertainty
• Dimensional and physical constraints
Meeting DOE efficiency standard and their customers’ dimensional and physical constraints simultaneously
Impact on Manufacturers
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Manufacturer Key Issues:
•Backsliding
Market may move from a highly customized market, to a commoditized market
Customized designs become less common
•Testing Methods and Systems
Manufacturing Process capabilities with Max. target Std. Deviation of 4%
The bigger the sample size, the closer the mean has to be to the Required Efficiency
Test Equipment Accuracy
•Design Optimization Customers’ response to DOE Rule
Will buyers purchase on Minimum Efficiency only or include a TOC evaluation?
Design optimization processes will change in response to purchasing practices
Impact on Manufacturers
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Impact on Customers
• For this rulemaking, DOE identified rural electric cooperatives and municipal utilities as transformer consumer subgroups that could be disproportionately affected
• NRECA commented that standards may encourage some utilities to stop evaluating transformer purchases for efficiency because the small differences between the energy savings and costs of evaluated and standard compliant transformers may no longer justify the cost of performing evaluations
• Impact to Customers of DOE efficiency standard will be proportional to their present purchasing practice
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Impact on Customers
• For Non-Evaluated Market:Expected Price Increase of 15% to 20%Weight Difference of –5% to +10%
• For Mid-Evaluated Segment (e.g., A=$3.00; B=$1.00):Expected Price Increase of 5% to 10%Weight Difference of 0% to +5%
• For High-Evaluated Segment (e.g., A>$4.50; B>$1.50):Typical current offerings meet or exceed DOE minimum efficiencies
DOE Impact on Designs Quoted
)/1000)]0.5 x 0.91 x LL((NL0.5 0.5/[kVA xkVA x x 100%EFF 2Equivalent A & B factors will be driven by NL/LL ratio to meet
DOE Min. Efficiency
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Customer Purchasing PracticesCurrent Purchasing Practices:
• Non-Evaluated Decision based on Lowest Price meeting ANSI/IEEE Standards
Leads to Low Efficiencies
• Total Owning Cost (TOC) Loss Evaluation TOC = (NL × A) + (LL × B) + Price
where:
o TOC = total owning cost ($),
o NL = no-load loss (Watts),
o A = equivalent first-cost of no-load losses ($/Watt),
o LL = load loss at the transformer’s rated load (Watts),
o B = equivalent first-cost of load losses ($/Watt), and
o Price = bid price (retail price)($).
TOC with Band of Equivalence (BoE)
• Efficiency Standards Evolution Energy Star ®
NEMA TP 1
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TOC and Band of Equivalence (BoE) ConceptsCustomer Purchasing Practices
Total Losses
$Cost of Losses
Transformer Cost
Total Owning Cost
3% BoE
~4 - 6 % lower First Cost
Lowest TOCDesign
A higher TOCdue to a 3% BoE, leads us to a ...
... lower First Cost Transformer, roughly 4-6%
$
$
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Customer Purchasing PracticesPurchasing Practices in a DOE Rule environment:
• For Non-Evaluated Segment:DOE Min. Efficiency will result in lower loss designsPurchase on lowest price from compliant bids?
• For Mid-Evaluated Segment (e.g., A=$3.00; B=$1.00):DOE Min. Efficiency will typically result in lower loss designPurchase Lowest Price only, or TOC, or TOC with BoE?
• For High-Evaluated Segment (e.g., A>$4.50; B>$1.50):Some DOE designs could result in less efficient, higher TOC unitsCustomers may choose to continue with TOC evaluations
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• Multiple winding connections
Dual Voltage
120/240 V on the secondary.
• Efficiency must be measured on the winding connection that produces the highest losses.
• This requirement imposes a significant additional burden on manufacturers
Outstanding Issues / Concerns
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Summary and Next Steps
From a Manufacturer’s Perspective:
• Understand how customers will purchase in a DOE standards environment
• Impact on Design Optimization Programs based on minimum efficiency and lowest material cost
• Review of standard materials
• Impact of global supply chain
• Flexibility of manufacturing and test processes
• IEEE Transformer Committee – assess impact on total industry
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Thank You!
Carlos GaytanManager of EngineeringDistribution TransformersEmail: [email protected]
April 29, 2008
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Bibliography.
10 CFR 431 Part III Energy Conservation Program for Commercial Equipment: Distribution Transformers Energy Conservation Standards; Final Rule. Issued Oct 12, 2007
10 CFR 431 Part III Energy Conservation Program for Commercial Equipment: Test Procedures for Distribution Transformers; Final Rule. Issued Apr 27, 2006
EERE Appliances and Commercial Equipment Standards, Distribution Transformers Web Page, last consulted on 12th Feb 2008.http://www.eere.energy.gov/buildings/appliance_standards/commercial/distribution_transformers.html
EERE Appliances and Commercial Equipment Standards, Technical Supporting Documentation for Final Rule (Distribution Transformers)http://www.eere.energy.gov/buildings/appliance_standards/commercial/distribution_transformers_fr_tsd.html
AK Steel Product Catalog, 2007
Personal communications with NEMA.
Report on Global Production of Silicon Steel by Sumitomo Corporation