Date: October 7, 2011 

TO: Richard Parker, DOE, Navigant, LBL and Negotiated Rulemaking Committee 

Members and NEMA Transformer Section Members 

SUBJECT: Comments on First Sessions of DOE Negotiated Rulemaking process for 

MVDT/LF and LVDT Distribution Transformers 

First, NEMA would like to thank the DOE and the Facilitator for providing an opportunity 

for NEMA to participate in the distribution transformer energy efficiency standards 

rulemaking process. We are confident that the Committee will arrive at a consensus on 

the best path forward that promotes energy efficiency and carbon reduction while still 

maintaining a reasonable payback for the consumers and keeping a vibrant transformer 

manufacturing industry in the United States. 

As you may know, NEMA is a leader in Smart Grid and Energy Efficiency. We hold 

leadership positions in the Smart Grid Interoperability Panel and High Performance 

Buildings related organizations. In addition, we spearheaded energy efficiency 

advancements by developing and promoting NEMA Premium Efficiency programs for 

motors, ballasts and low voltage dry-type distribution transformers. 

NEMA believes that a negotiated rulemaking can create a win-win situation for all the 

stakeholders. However, in order to be successful in the long run, we need to start with 

an engineering cost model and input assumptions that have been fully vetted by the 

stakeholders. At this point, there is a lot of confusion as to whether we have a 

reasonable model or not. We feel that validating the existing model and input 

assumptions is a critical starting point. 

NEMA, various transformer manufacturers, H-Volt and others have documented serious 

errors and problems with the OPS model and the technical analysis results reported in 

both March 2011 and August 2011. The transformer manufacturers have been working 

aggressively with Navigant and DOE to resolve the discrepancies and create a model 

that accurately estimates the cost effectiveness of various proposed energy efficiency 

levels. 

As Raymond Polinski of ATI Allegheny Ludlum stated in his written comments of 

September 23, 2011, “Until the committee’s transformer design specialists and utility 

engineering experts sign-off on the analysis (basis on which the committee will make 

our recommendation) it is difficult to propose or debate new efficiency standards. “ 
Several transformer manufacturers and utility organizations have already provided 

specific comments and recommendations concerning needing greater clarity on the 

input assumptions used in the modeling. We support those requests and will not repeat 

them here. The general observation is that the entire approach and analysis is 

extremely complicated and only a few people on the committee fully understand the 

entire analysis process or the results. However, these results will drive the discussion 

that may ultimately become a consensus position for the industry and the committee. 

NEMA therefore requests that the DOE and its consultants take extra care to validate 

the results and explain the results in a logical, simple manner. 

RECOMMENDED VALIDATION PROCESS: 

NEMA recommends the following validation process for developing a consensus 

position on the energy efficiency levels for distribution transformers: 

1. Have the transformers manufacturers and users validate the results of the OPS 

model and the Navigant analysis in terms of price per efficiency level for Medium 

Voltage Dry-Type (MVDT), Liquid Filled (LF) and Low Voltage Dry-type (LVDT) 

transformers. Currently, a least a few liquid-filled transformer manufacturers feel 

that the most resent Navigant results are “in the right ball park”. However, the 

MVDT and LVDT results have not been validated yet. 

2. Once the price per efficiency level results of the three transformer classes have 

been validated, then the input assumptions for the life-cycle cost analysis need to 

be reviewed and approved by a consensus of the negotiated rulemaking 

committee. These input assumptions should include: electricity costs, load factor, 

average lifetime of transformers, etc. 

3. Review and validate the results of the life-cycle cost analysis performed by 

Lawrence Berkeley Lab. Verify that the concerns noted in this document are 

considered in the LCC particularly with regard to ensuring that selected efficiency 

levels provide multiple designs and multiple suppliers. 

4. Review and validate the results of the National Impacts Analysis. 

5. Review and validate the results of the Manufacturers Impacts Analysis. Verify 

that the concerns noted in this document are considered in the MIA. 

GENERAL COMMENTS AND RECOMMENDATIONS PERTAINING TO ALL 

DISTRIBUTION TRANSFOMER CLASSES: 

1. Sensitivity Analysis - We feel strongly that a selling-price sensitivity analysis 

needs to be performed on any design lines where the analysis results indicate 

that efficiencies higher than the existing rules are warranted. This is particularly 
important in situations where the most cost effective design includes amorphous 

materials or ZDMH. 

2. Core Material Supply Availability - We are concerned that some of the core 

steels, like amorphous, that seem to fit the “best efficiency answer” cannot be 

produced in the foreseeable future in adequate supply to satisfy the demand 

precipitated by some of the higher proposed DOE efficiencies. 

3. Core Material Price Concerns - Due to concerns about supply limitations, single 

or too few suppliers, and the resulting potential for significant price increases 

related to the very highest efficiency core materials such as Hi-B steels and 

Amorphous metal, NEMA members believe an Efficiency Level that allows 

grades of silicon steel with proven global supply capacity such as M3 to compete 

economically with Hi-B and Amorphous would be the Efficiency Level that would 

meet the requirements for the best technology that is economically justifiable. 

Anything higher, in our opinion, could result in a serious disconnect between the 

material prices used in the DOE economic analyses and what could actually 

happen in the market. In that case, the projected economic benefits would not 

be realized and the higher standards would lead to supply issues that would 

affect distribution transformer manufacturers' ability to meet customer demands 

for critical US transformers. 

4. Multiple Designs and Suppliers - We feel strongly that any efficiency levels 

mandated by the DOE should ensure that there are multiple suppliers that can 

provide the materials needed for the lowest cost designs. In addition, it is 

important to be able to reach the same efficiency levels with multiple designs 

using multiple metal combinations. Ideally, these different designs and material 

combinations will have relatively small price bands of less than 20%.

5. Impact on Small and Medium-sized Manufacturers - Small and medium-sized 

manufacturers are concerned that designs requiring amorphous metal or wound 

cores will require large investments, drastic changes in current manufacturing 

processes, and potentially much higher future transformer costs. In addition, 

small and medium-sized manufacturers may have difficulty obtaining some of the 

less conventional materials. Manufacturers with the most access to the limited 

supply materials (e.g., ZDMH, Amorphous) would have an unfair competitive 

advantage which at higher EL’s, could not be offset by the use of conventional 

high efficiency core steels such as M3. 

6. The Institute of Electrical and Electronics Engineers (IEEE) assumes an average 

life for distribution transformers of 20.5 years. What research does Navigant or 

the DOE have that supports the 32 year average life assumed in the current 
Navigant analysis. NEMA recommends using the 20.5 years average life from 

IEEE. 

7. The DOE should ensure a logical consistency in the final regulation that does not 

provide an artificial economic benefit for moving between kva ratings within a 

given equipment class or between equipment classes. The relations between 

kva and losses should maintain the fundamental power relationship as closely as 

practical.

 

COMMENTS AND RECOMMENDATIONS BY SPECIFIC TRANSFORMER CLASSES: 

LIQUID IMMERSED 

1. We support dividing liquid immersed transformers into pole mounted, pad 

mounted, network/vault, and substation categories because each of these 

categories has different limitations on weight, height and size. In particular, in 

many cases, larger transformers can not fit into existing vaults and still maintain 

required safety and maintenance clearances. 

The DOE noted in the first MVDT/LF negotiated rulemaking session that their 

analysis indicated that the higher efficiency levels for pole mounted transformers 

could be met without exceeding the weight and height restrictions on existing 

poles. This finding is not supported by manufacturers’ or utilities’ experience. The 

DOE needs to provide the analysis that supports the conclusion that existing 

poles would not need to be replaced to support higher efficiency transformers. 

The potential height and weight restrictions on existing poles needs to be taken 

into account before setting the efficiency levels for pole mounted liquid filled 

transformers. In addition, since many manufacturers use the same transformer 

core design for both the pad mounted and the same sized pole mounted 

transformers, the efficiency levels for both units may need to be the same. 

2. The BIL (Basic Impulse Rating) rating of a transformer has a significant impact 

on the losses of the product. This is so because the clearance between the 

windings and the core must increase as the BIL increases resulting in a greater 

volume of core steel and thus a greater amount of no load losses.  

This impact was recognized by the DOE for the MV Dry-Type (MVDT) efficiency 

standards established in 2010. However the DOE did not recognize this impact 

with the MV Liquid-Filled (MVLF) standards. The MVLF efficiency standards 

cover a range of BIL ratings up to and including 200 KV. The DOE 

representative designs, upon which the standards were developed, included 95, 
125, and 150 BIL for single-phase and 95 and 125 BIL for three-phase.  

But the standard was written independent of the BIL rating which meant that it 

had to be applicable to all ratings (including up to 200 BIL). The market is 

dominated by 95BIL which may then have opportunities for further improvements 

in the efficiency specification if it is segmented as a separate equipment class. 

 However, without separation, it may prove to be difficult to significantly improve 

the standard and still accommodate the 200BIL ratings. We recommend 

consideration be given to defining separate standards in MVLF for significant BIL 

groups: <= 95 BIL and >95 BIL. These should be defined in such manner as to 

ensure movement from one BIL rating to another is not economically 

advantageous from an efficiency regulation perspective.

3. Currently, a least a few liquid-filled transformer manufacturers feel that the most 

resent Navigant results are “in the right ball park”.

MEDIUM VOLTAGE DRY TYPE 

1. At this point, there are many questions from the manufacturers and others 

concerning the current analysis output. As noted earlier, additional work needs to 

be done to validate the results of the price vs. efficiency analysis. 

LOW VOLTAGE DRY TYPE 

1. There are some LVDT transformers that are used in specialty applications such 

as in datacenters and uninterruptible power supplies (UPS’s). The loading on 

these transformer applications is significantly different than the average 

transformer. NEMA recommends that a limited number of specialty applications 

be analyzed to determine if these applications warrant different efficiency 

standards. 

2. The recent Navigant analysis indicates that the curve between transformer price 

and efficiency for low voltage dry type transformers is relative flat. This result 

doesn’t seem reasonable and requires further validation. At least two of the 

manufacturers attending the first LVDT session indicated that their prices will 

increase roughly 60% between the base case (EL0 and EL3). 
EXCERPTS OF OTHER COMMENTS FROM NEMA TO DOE (EERE-2010-BT-STD0048) DATED APRIL 18, 2011 CONCERNING CONSERVATION STANDARDS FOR 

DISTRIBUTION TRANSFORMERS. 

ES.3.1 Efficiency Requirements for Dual/Multiple-Voltage Secondaries

DOE should align its requirements with those of IEEE standards (C57.12.00 for liquid-filled, 

NEMA ST20-1992: 3.3 for low voltage), requiring testing in the “as shipped” condition. For 

units with multiple (series-parallel) low voltage ratings, the efficiency standard should be based 

on the highest voltage (series) connection, which matches the IEEE standard and industry 

practice. To do otherwise would be counter to the current industry standards and practices of 

testing and shipping multiple low voltage rated units at the higher voltage (series) rating. For 

example, the most popular low voltage rating for single-phase US Liquid-Filled DT’s is the 

120/240 volt rating consisting of two half-capacity low voltage windings connected internally in 

series. IEEE standards require such units to be connected and tested at the higher 240 volt 

(series) connection. For 240/480 volt ratings, the series connection would be at 480 volts. Our 

recommendation is that DOE match this requirement for efficiency standards compliance. 

ES.3.2 Dual/Multiple-Voltage Transformers with Varying Basic Impulse Levels

DOE should align its requirements with those of IEEE standards (C57.12.00 for liquid-filled, 

NEMA ST20-1992: 3.3 for low voltage), requiring testing in the “as shipped” condition. For 

units with two or more high voltage ratings, the efficiency standard should be based on the 

highest voltage (highest BIL) connection, which matches the IEEE standard and industry 

practice. To do otherwise would be counter to the current standards and industry practices of 

testing and shipping D/V units at the higher voltage rating. For example, the most popular D/V 

rating for US LFDT’s would be the 12470GrdY/7200 x 24940GrdY/14400 rating (95 kV BIL x 

125 kV BIL). IEEE standards require such units to be connected and tested at the higher voltage 

rating – 24940GrdY/14400. Our recommendation is that DOE match this requirement for 

efficiency standards compliance. 

ES.3.11 Scaling Methodology

The 0.75 scaling rule is imperfect, as would be any scaling methodology. While the scaling rule 

is sufficiently accurate when applied to units with a kVA value close to the kVA value of the 

representative unit, as the distance between the representative unit and the scaled unit increases, 

so does the inaccuracy of the scaling rule. NEMA’s recommendation is to retain the 0.75 scaling 

rule and to simply add more design lines to its analysis, as a reality check, to ensure the scaling 

rule keeps its integrity. 
ES.3.17 Trial Standard Levels – Substitution Impact

Medium voltage three-phase liquid-filled and dry-type transformer compete in certain markets. 

Some users will pick a transformer type (liquid-filled or dry-type) based on total installed costs, 

which include any requirements associated with the cooling used. For some applications, 

additional costs are involved for liquid-filled for liquid containments or fire protection. If liquidfilled transformers have efficiency requirements that are significantly more stringent than drytype transformers, the cost equation could shift such that users might start installing dry-type 

transformers where previously liquid-filled transformers were used. This could have the 

unintended consequence of lowering the efficiency for that installation (as dry-type have lower 

efficiency requirements than liquid-filled), rather that raising the efficiency as DOE rules are 

intended to make happen. 

ES.3.18 Impact on Manufacturers – Potential for Increased Refurbishments

NEMA urges DOE to discuss the supply of core steels and other materials with individual 

manufacturers, both large and small, to understand the full perspective on material supply. 

It is our contention that higher standards will lead to an increased amount of refurbishment of the 

existing inventory of transformers, which are not required to comply with new standards. We 

believe the analysis, by not taking this into account, may be overestimating how quickly new 

transformers are adopted in the field. We recommend that the analysis, at each CSL/TSL, ought 

to include the impact of the “buy vs. repair” decisions made as the cost of a new piece of 

equipment increases. 

 

To help predict what the supply and cost of steel may be in the future, DOE should take lead in 

forecasting these values at each CSL/TSL. 

ES.3.19 Supply of Core Steels

NEMA urges DOE to discuss the supply of core steels with individual manufacturers, both large 

and small, to understand the full perspective on steel supply. 

To help predict what the supply and cost of steel may be in the future, DOE should take lead in 

forecasting these values at each CSL/TSL. 

ES.3.20 Valuing Air-Borne Emission Reductions

NEMA does not disagree with the proposed approach but recommends the analysis pair a 

quantified CO2 impact with each TSL level and that the CO2 impact be reasonable, repeatable, 

and based on quality data. 
ES.3.25 Replacement and Maintenance Practices

It is our contention that higher standards will lead to an increased amount of refurbishment of the 

existing inventory of transformers, which are not required to comply with new standards. We 

believe the analysis, by not taking this into account, may be overestimating how quickly new 

transformers are adopted in the field. We recommend that the analysis, at each CSL/TSL, ought 

to include the impact of the “buy vs. repair” decisions made as the cost of a new piece of 

equipment increases. 

ADDITONAL TECHNICAL COMMENTS: 

Exclusion of Mining Transformers 

We understand mining transformers are not required to comply with current conservation 

standards. However, we also note that mining transformers are not named on the list of 

exempted products. Therefore, we recommend mining transformers be included on the 

exemption list to clarify that the standards shall not apply to mining transformers. 

Step-Up Transformers 

If step-up transformers are going to be included within the scope of applicability, we recommend 

segregating “modulation transformers” from the broader group of step-up transformers, and 

exempting them from the efficiency requirements. Modulation transformers do not represent an 

opportunity for significant energy savings.