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The Ramifications of the New Transformer Efficiency Standards
from DOE
IEEE REPC MeetingCharleston, SC
4/29/08
Alan L. WilksChief Technical Officer
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Discussion Outline
1. How the DOE Rule Impacts: Cost Delivery Size Loss Formulas Testing Future Changes
2. Example Calculations
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Impact on Cost
Major factors on Cost Raw Material Cost
Core Steel – UP (DOE uses more, all high quality)Copper – UP (DOE uses more)Aluminum – UP (DOE uses more)Oil – UP (DOE uses about same or less)
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Raw Material Cost History
Raw Material Cost
1.0
1.5
2.0
2.5
Apr-04 Apr-05 Apr-06 Apr-07 Apr-08
Co
st M
ult
iplie
r
Oil
CU
Core Stl
AL
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Impact on Cost
Availability of Raw Materials Core Steel – Limited Supply (High Quality)
Major factors on Cost (Cont.)
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Availability of Raw Material – Core Steel
XX
XXX
X – High quality (M3 or better) steel producers
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Continued high demand in China Domestic steel vendors plans:
Modest production increases by 2010 No plans on adding significant capacity
Takes 3 years after deciding
Availability of Raw Material – Core Steel
World shortage of high quality core steel
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Core Steel Consumption
Consumption based on 2007 usage, an average production year.
2007 Actual 2007 Converted toDOE
Transformer Plant@ Full Capacity
M6
M2
M3
Allotment
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Impact on Cost
Major factors on Cost (Cont.)
Production CapacityHigher efficiency transformers require:
Larger cores More winding turns
Results in more manufacturing time, slightly limiting production capacity
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Overall Impact on Cost
DOE estimated an increase in first cost of 6-12% Based on 2006 material costs and no escalation
This estimate was a generalization and too low Impact on cost depends upon individual utility
purchasing techniques Difficult to predict costs next month, let alone
2010 Best way to determine cost impact is to get
quotes on DOE and non-DOE transformers
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Impact on Delivery
Delivery will be impacted as materials are in short supply
Steel vendors will continue to have manufacturers on allocation
Core steel rationing may cause transformer production to be limited
ERMCO will support long-standing customers as first priority
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Impact on Delivery
Storm emergency transformers will be greatly impacted
Options will be:Build storm restoration units and delay othersUtilities carry more inventoryDistributors carry more inventoryPetition DOE for a temporary waiver for storm
units
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Impact on Size (1Ø)
DIM.kVA Eval. Wt. Gal. Dia. x Ht.
15 Pole Non Eval 247 10 13 x 24$3/$1 262 9 13 x 24DOE 274 9 13 x 24
25 Pole Non Eval 358 18 15 x 30$3/$1 363 13 15 x 26DOE 401 13 15 x 26
Width x Depth
25 Pad Non Eval 533 25 32 x 28 $3/$1 553 24 32 x 28 DOE 601 26 32 x 29
50 Pad Non Eval 711 32 32 x 31$3/$1 710 28 32 x 31DOE 757 30 32 x 34
+27#, =Size
+43#, -4”H
+68#, +1”D
+46#, +4”D
Change
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Impact on Size (3Ø)
DIM.kVA Eval. Wt. Gal. Width x Depth
500 Non Eval 5,202 260 60 x 45$3/$1 4,967 180 56 x 45DOE 4,824 207 56 x 45
1500 Non Eval 9,979 430 66 x 55$3/$1 9,942 418 66 x 55DOE 9,864 417 66 x 55
2500 Non Eval 13,423 580 72 x 59$3/$1 13,956 496 72 x 59DOE 13,588 527 72 x 59
-378#, -4”W
-115#, =Size
+165#, =Size
Change
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Impact on Loss Formula
Non-Compliant
Compliant
98.91%
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Impact on Loss Formula
Generally Speaking – Loss formulas of $4.50/$1.00 for 1Ø and
$3.00/$1.00 for 3Ø usually meet DOEHigher formulas will result in more efficient
units than DOELower formulas will have no effect on
efficiency, but may shade the loss ratio in one direction or another to minimize TOC
No formula will result in lowest cost without regard for TOC
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Impact on Loss Formula
Since formulas reflect the Total Owning CostContinue to use a formula if believed to be
accurate.Using a formula will result in:
An optimum ratio of core to winding lossA most cost effective design based on TOC
Not using a formula will result in:A DOE design at minimum cost.
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Impact on Testing
Manufacturers must verify compliance by:100% testing, orAlternative Efficiency Determination Method
(AEDM) sampling plan Enforcement is by the Honor System
Manufacturers must report lowest efficiency models to DOE
Violators will be found by whistleblowersDOE may seek civil penalties for non-
compliance
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Tolerances
The stated DOE efficiency levels are minimum averages for a modelA model is defined by electrical characteristics
However, DOE allows a toleranceThe average efficiency of the sample X must be:
Avg.Eff.(X) ≥ 100 / (1+(1+0.08/SQRT(n))*(100/RE-1))
Where: n = number of units in sample RE = represented efficiency (DOE’s specified value)
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Example Tolerance (25 kVA)
Avg.Eff.(X) ≥ 100 / (1+(1+0.08/SQRT(n))*(100/RE-1))
RE = 98.91% Efficiency
For: n Avg.Eff.≥
1 98.824
10 98.883
100 98.901
1000 98.907
25 kVA Tolerance
98.80
98.82
98.84
98.86
98.88
98.90
98.92
1 10 100 1000
X Units Tested
Eff
icie
ncy
DOE EFF (RE) MIN AVG EFF (X Units) ABS MIN (1 Unit)
DOE Specified (RE)
Minimum Average (X Units)
Absolute Minimum (1 Unit)
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Future Changes ?
Lawsuits may affect future efficiency levelsEarthjustice has filed suit on behalf of:
Sierra ClubNational Resources Defense Council (NRDC)
California Attorney General’s office has filed a similar suit
Both suits claim the standards are too weak and will lead to excessive energy consumption and unnecessary global warming pollution
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Future Changes ?
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Future Changes ?
Fast track temporary waiver of DOE efficiency requirement in the event of storm emergencies.
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Supplemental Information
Example Calculations
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Example Calculations
Efficiency = Output / InputkVA*1000 / (kVA*1000 + Losses)
DOE BasisNo Load Losses @ 20°CLoad Losses @ 55°C (exc. auxiliary losses)50% load
Eff = kVA*1000*0.5 / [kVA*1000*0.5 + NL20°C + LL55°C*(0.5)2]
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Example Calculations (cont.)
Temperature Corrections No Load
If quoted at 85°C, then
NL20°C = NL85°C * TCF where TCF =
1.04225 = 1 + 0.00065 * (85° - 20°)
No LoadIf quoted at 85°C, then
LL55°C = LL85°C * TCFwhere TCF =
0.9032 for AL/AL (225+55)/(225+85)0.9045 for CU/AL (229+55)/(229+85)0.9061 for CU/CU(234.5+55)/(234.5+85)
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25 kVA Example
Losses: NL20°C = 60 watts
LL85°C = 334 watts (CU/AL)
Efficiency Calculations:
LL55°C = 334 * 0.9045 = 302.1
Eff = 25,000*0.5/(25,000*0.5 + 60 +
302.1*0.52)
Eff = 98.93%
DOE Rule = 98.91%, therefore this unit meets DOE
