Product Definition and Analysis Approach for Distribution Transformers Version 1: 8 October 2013

Contents 1 2 3 4

Distribution Transformers Summary Definition and Data Requirements .......................... 2 Introduction...................................................................................................................... 4 Policies on Transformer Efficiency ................................................................................... 4 Product Sub-Category Rationalisation ............................................................................. 6 4.1

Technology ............................................................................................................... 8

4.1.1 4.1.2 4.1.3 4.1.4 4.1.5 4.1.6 4.1.7 4.1.8 4.1.9 4.2

Matrix Row A): Type of Transformer: Dry or Liquid-Filled ................................... 8 Matrix Row B): Power Capacity, or Rated Power ................................................ 8 Matrix Row C): Transformer Design for Number of Phases ................................ 9 Matrix Row D): Design frequency of supply ........................................................ 9 Matrix Row E): Voltage Class ............................................................................10 Matrix Row F): Secondary Winding Voltage Class .............................................10 Matrix Row G): Cooling Sub-Type .....................................................................10 Matrix Row H): Winding Configurations .............................................................11 Matrix Row J): Impedance .................................................................................11

Features and Functionality.......................................................................................11

4.2.1 4.2.2

Matrix Row K) Type of Transformer ...................................................................11 Matrix Row L) Mounting Type ............................................................................13

5 Metrics ............................................................................................................................13 6 Market Segmentation for Benchmarking by Product Application .....................................15 7 Test Methodologies ........................................................................................................16 8 Normalisation of Data from Each Region ........................................................................17 9 Approach to the Data Analysis........................................................................................18 10 Data Sources ................................................................................................................19 11 Data Requirements.......................................................................................................20 Appendix 1: Indicative relative levels of ambition for transformer policies .............................21 Appendix 2: Derivation of indicative efficiency conversion factors between 50Hz and 60Hz transformers .........................................................................................................................23 Appendix 3: Efficiency metrics for transformers ....................................................................25

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1 Distribution Transformers Summary Definition and Data Requirements This product definition document explains the (1) product scope, (2) metrics and (3) data requirements for the mapping and benchmarking of the energy performance of distribution transformers. Table 1: Summary Product Categorisation Matrix (for explanation see section 4) Generic definition & scope

Transformer means a static piece of apparatus with two or more windings that, by electromagnetic induction, transforms a system of alternating voltage and current into another system of alternating voltage and current usually of different values and at the same frequency for the purpose of transmitting electrical power. A distribution transformer takes voltage from a primary distribution circuit and steps down to a secondary distribution circuit, most commonly between 10 kVA to 2.5 MVA with input voltage between 1.1 kV and 36 kV (Source: EU ecodesign definition and EN 50464-1)

Transformer characteristics

     

Type of cooling fluid - liquid-filled or dry-type Operating frequency, usually 50Hz or 60Hz Number of phases: single-phase or three-phase Power handling capacity (i.e., the kVA rating) Voltage class, based on winding insulation Designed for installation on a pad, a pole, or other

Excluded from scope:

Other characteristics

Metric



All specialist transformer sub-types are excluded (e.g. Phase (or Scott-T) transformer; Autotransformer; Drive (isolation or Safe Extra Low Voltage (SELV) transformer, welding transformer, etc.)

  

Winding configuration Impedance Other features and data, as available

Current assumption is to compare the maximum losses associated with the transformers at 50% rated load and using the IEC-based definition of efficiency subject to comment from participants. (Final decision to be confirmed, but options are:    

Maximum no-load and load losses reported separately in watts of power loss. Per cent efficiency according to the IEC definition at a particular rated loading point. Per cent efficiency according to the ANSI/IEEE definition at a particular rated loading point. Power loss index – a calculated ratio of losses for the power throughput of a transformer, possibly combined with the maximum efficiency to derive a power-loss index calculated at a peak efficiency point for each kVA rating.)

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Table 2. Summary of Performance Data Requirements (for full details see section 11) Essential product performance data

For each distribution transformer:

A. B. C. D. E. F. G. H.

Time period of interest Other useful information

Transformer type and description, with any available features Number of phases (1 or 3) Operating frequency (50Hz or 60Hz) kVA rating and whether it is based on the input rated power (IEC) or output (ANSI/IEEE) Voltage rating of the high-voltage winding Voltage rating of the low-voltage winding The no-load (i.e., core steel and stray) losses (W) The load-losses (i.e., winding losses) at rated load (W), plus confirming the rated load (%) at which this is measured

Distribution transformer performance data, as outlined above, is invited primarily for 2010-2012, but also historical data for establishing trends back to 1980.

I.

The design temperature rise of the windings in degrees Celsius (if available) J. Tap range – whether the transformer has taps, and if so, the range from highest to lowest

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2 Introduction Transformers operate 24 hours/day, 365 days per year and have very long lifetimes, typically more than 30 years. Energy consumption during its service life is the dominant factor in their life-cycle assessment environmental impact. Furthermore, the increased use of electronic equipment and other non-linear loads can lead to increased harmonic currents and higher losses in transformers. Technical solutions exist on the market leading to reduced energy consumption of transformers, but the market penetration of highly efficient transformers is lower than it could be. Larger transformers are generally more efficient, and those models used in electricity distribution usually have an efficiency level better than 98%. Efficiency levels vary by technology and by region, as do the energy-efficiency policies in different parts of the world. This document describes the development of a common framework to categorise types of distribution transformers, and an approach to compare and contrast the efficiency of these transformers from various countries and regions around the world.

3 Policies on Transformer Efficiency Many governments around the world have realised the energy savings potential of distribution transformers and have adopted programmes to support and encourage efficiency. This section provides a brief summary of some of the programmes that overlap with the scope of coverage for this work: 1. Australia: Mandatory energy performance standards 1 for liquid-filled and dry-type distribution transformers with power ratings from 10 kVA to 2500 kVA intended to be used on 11 kV and 22 kV networks. Effective since 2004, the MEPS are set out separately for single phase and 3-phase transformers with minimum efficiency values at 50% of rated load in AS 2374.1.2. 2. Canada: Mandatory energy performance standards 2 were adopted for dry-type distribution transformers that came into force in April 2012. This regulation harmonised Canadian requirements with the 2010 requirements for dry-type transformers in the USA. The Canadian regulations apply to 60 Hz dry-type medium voltage transformers, 35 kV or less, single-phase rated 15 to 833 kVA, and threephase rated 15 to 7500 kVA. MEPS are set out separately for dry-type single phase and 3-phase transformers as power efficiency levels at 50% of nominal load. (The new Canadian regulation superseded the previous one 3 that covered dry-type transformers having a primary voltage greater than 1.2kV which came into force in 2005). 3. USA: Mandatory standards 4 covering three types of distribution transformers: lowvoltage dry-type that came into force in 2007, and liquid-filled and medium-voltage dry-type that came into force in 2010. MEPS are set out separately for single phase and 3-phase transformers as power efficiency levels at 35% of nameplate rated load for low voltage dry-type, and at 50% of nameplate rated load for others. A second tier of requirements for all of these products takes effect in January 2016. 1

See http://www.energyrating.gov.au/products-themes/industrial-equipment/distribution-transformers/meps/ See http://oee.nrcan.gc.ca/regulations/bulletins/16910 3 See http://oee.nrcan.gc.ca/regulations/bulletins/10086?attr=0 4 See http://www1.eere.energy.gov/buildings/appliance_standards/product.aspx/productid/66 2

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4. Japan: The top runner programme sets minimum sales-weighted efficiency 5 for 'transformers for high-voltage receiving and distribution' for 2006 for liquid-filled transformers and 2007 for cast-coil dry-type transformers. The programme sets out formulae given that calculate 'Total allowed loss' (sum of the load and no-load loss in Watts) of transformer based on its capacity in kVA - separately calculated for single phase and 3-phase types, and frequency (i.e., 50Hz and 60Hz). The reference load factor is 40% for a transformer capacity of 500 kVA or less, and 50% for a transformer capacity greater than 500 kVA. 5. India: The Indian government made their energy label scheme6 applicable to liquidfilled, naturally air cooled, three phase, and double wound non sealed type outdoor distribution transformers, from 16 to 200 kVA. A star rating is given according to a maximum measured total losses (i.e., combined core and coil losses) at 50% and at 100% load. Starting from 20 August 2010, the government of India directed the Central Electricity Authority to purchase oil-filled distribution transformers that meet the three star rating specified by the Bureau of Energy Efficiency (BEE), or another prescribed minimum efficiency value for kVA ratings not specified by BEE. 6. Republic of Korea. In July 2012, Korea adopted mandatory efficiency standards for liquid-filled and dry-type distribution transformers. Korea covers dry-type transformers from 50-3000 kVA and liquid-filled from 10-3000 kVA, setting a minimum efficiency requirement at 50% loading separately for single phase and three phase. In addition to the MEPS level, Korea also sets a higher level of efficiency and requires that manufacturers meet that level before they can market the product as highly energyefficient. 7. European Union: In July 2013, the EU published draft EU ecodesign requirements for small, medium and large power transformers. Small means not exceeding a high voltage of 1 kV and for which maximum no load and load losses at 100% of rated capacity are stipulated by kVA rating; Medium means with a high voltage winding with a rated voltage between 1 kV and 36 kV and for which maximum no load and load losses at 100% of rated capacity are stipulated by kVA rating, separately for liquid immersed and dry type and for below and above 4000 kVA; Large means with a high voltage winding with a rated voltage exceeding 36 kV for which minimum peak efficiency levels will be stipulated (percentage peak efficiency). The distribution transformers being addressed in this M&B analysis correspond closest to the medium power transformers in Europe. 8. China: In China, the government is pursuing the promotion of energy efficiency standards for distribution transformers – both liquid-filled and dry-type. GB 20052 specifies the energy efficiency grades, minimum allowable values, energy saving evaluation value and test methods of three-phase distribution transformers. It is applicable to liquid-filled transformers with 10kV primary and rated capacity of 301600 kVA and dry-type with rated capacity of 30-2500 kVA. The regulation establishes maximum no-load and load losses at 100% of rated capacity. 9. Mexico. Mexico has national standards (NOM-002) that apply to both single-phase and three-phase liquid-filled transformers for pad, pole, substation and submersible installations, rated 15 to 167 kVA for single-phase and 15 to 500 kVA for three-phase. The requirements are presented in the national standard both in terms of per cent efficiency at 80% loading and as maximum watts. Further details of each of these policies are given in Appendix 1.

5

The Research Committee For Total Energy The Energy Conservation Standards Working Group, The SubCommittee For Judgment Criteria For Transformers, Summary Of Final Criteria, April 3, 2002. See http://www.eccj.or.jp/top_runner/pdf/tr_transformers_summary.pdf. 6 See http://220.156.189.26:8080/beeLabel/Schedules/Schedule4-DistributionTransformer.pdf

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4 Product Sub-Category Rationalisation This section explains the rationale behind the summary definition presented in section 1, and how this was developed. Table 3 shows the first proposed way to break down the product category, and each aspect is discussed in the following sections. Table 3: Initial Matrix Definition of Possible Transformer Sub-Categorisation Aspect A

Technology

Cooling / Insulation type

Possible Permutations  

Dry-type (cast coil and open ventilated) Liquid-filled (usually oil)

Comments Key attribute for efficiency

B

Technology

Power capacity, or rated power

Range of kVA or MVA. Must be clear if input power or output power.

Key attribute for efficiency

C

Technology

Phase(s)

 

Single phase 3 phase

Efficiency will be different for same kVA ratings depending on phases

D

Technology

Design frequency of supply

 

50 Hz 60 Hz

Minor impact on 7 efficiency

E

Technology

Voltage class (input voltage), also called Basic Impulse insulation Level (BIL)



Medium voltage (can have subgroups) Low voltage

Key attribute for designation, especially for dry-type transformers



F

Technology

Voltage class (output voltage)

 Voltage (or range) in kV

Lower voltages have high currents, can impact efficiency

G

Technology

Cooling subtype



Self-cooled (no active cooling)

Probably low importance to benchmarking (TBC)

H

Technology

Winding configuration



Delta/Y/Star, and variants

Probably low importance to benchmarking (TBC)

J

Technology

Impedance

 Percentage value (e.g. in a range of >3% and 36 kV to ≤ 230 kV. Large power transformers are generally viewed as those with base self-cooled power ratings exceeding 60 MVA and always including all high voltage ratings of 230 kV as well as all extra high voltage (EHV) ratings of 245 kV or more. Large power transformers can be found at generating power stations and electrical substations to convert electrical power to high voltages for transmission and then back down again at the other end to a medium power transformer for transferring power to a sub transmission circuit. From medium power transformers, the voltage is further reduced by medium voltage distribution transformers into circuits where the electricity is distributed to end users. Transformers with their highest voltage at 36kV or below are generally referred to as “distribution transformers” – the focus of this paper. Distribution transformers are appropriately named because they are installed in the distribution circuit of electricity networks servicing residential areas and commercial and industrial customers. Distribution transformers are most often involved in stepping voltage down. In some markets, such as North America, there is also a special subgroup of low-voltage distribution transformers that have a primary voltage less than or equal to 1 kV. These transformers, called low voltage dry-type transformers, can be found situated within buildings or facilities, working to reduce losses within the building’s internal electrical distribution system. Medium voltage distribution transformers operate between 1 and 36 kV, and can be dry-type including epoxy-cast resin (each of which are cooled with air) or liquid-filled (which are cooled with mineral oil or some other insulating liquid). The table below summarises the broad groups of transformers and describes their most common uses. While the naming conventions are not necessarily consistent around the world, from a practical perspective, the following does represent how they are used in transmission and distribution systems.

Table 4-2. Overview of the General Transformer Groups Transformer Group Large Power

Medium Power

Medium Voltage Distribution Low Voltage Distribution

Voltage

Phases

>245 kV (High voltage) >36 kV and ≤230 kV (Medium voltage) ≤36 kV (Medium voltage) ≤1 kV (Low voltage)

Single and Three

Typical Insulation Liquid-filled

Single and Three

Dry-type or liquid-filled

Single and Three

Dry-type or liquid-filled

Single and Three

Dry-type

Common Use Stepping up to or down from higher voltages for transmission of electricity over distances; substation transformers Stepping voltages down from a sub transmission system to a primary distribution system Stepping voltages down within a distribution circuit from a primary to a secondary distribution voltage Stepping voltages down within a distribution circuit of a building or to supply power to equipment

The project participants have decided to focus on distribution transformers, for which there are more programmes internationally and greater potential for comparative performance results. 

Proposal: To focus on distribution transformers, both medium voltage and low voltage (as shown in the bottom two rows of the above table)

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4.2.2 Matrix Row L) Mounting Type Distribution transformers are designed for a particular installation, such as on a pole (generally out of reach of people) or on a pad (where general public may have access such as in a front garden, or in a small fenced-off / sign-posted area). The safety requirements commensurate with the intended installation site are different, with greater protection for accidental contact afforded to those transformers that are mounted on the ground. For pole-mounted transformers, there can be issues with electric utilities having certain maximum carrying capacities on their poles, and yet as these transformers are made more energy-efficient, they will increase in weight due to the additional core steel and windings. Therefore, there can be – and has been discussion and decision based around – weightconstrained pole-mounted installations in some of the regulatory proceedings for distribution transformers, including Europe and North America. The fact that these units are intended for installation on a pole can impose limits on weight and physical size, thus affecting design and maximum levels of efficiency (in addition to the safety requirements). However, although there are some constraints, there are also measures that can be incorporated into the design to improve efficiency without necessarily increasing weight. This includes switching to all-copper conductors and using higher-grades of core steel – however both of these measures would add cost to the transformer. Therefore, regulators have considered establishing slightly less rigorous requirements for pole-mounted transformers that are weight constrained (i.e., those that fall within the largest kVA ratings of pole-mounted installations). For the purposes of the data collection exercise, it should be sufficient at this point simply to note whether the transformer is a pole-mounted installation or not. If it is a pole-mounted installation, it will be put into a separate group of kVA ratings for analysis, to determine whether there is any departure from the efficiencies of the non-pole mounted transformers of the same kVA ratings. The results of this comparison (assuming sufficient data is available for this analysis) will be reported in the final report, and if warranted, mounting type may be used as a differentiator in the final results. 

Proposal: To include pad-mounted and pole-mounted transformers in the data collection part of the study, then analyse to see whether any differentiation is warranted in the results.

5 Metrics Many countries regulate transformers by establishing maximum values of loss (in Watts) of core losses and of coil losses at full load (i.e., rated capacity). Other countries regulate transformers through a percentage efficiency requirement at a specified loading point. Having a percentage efficiency rather than maximum losses provides more flexibility in the design process, enabling manufacturers to provide a greater variety of designs and be more responsive to the needs of utilities. Appendix 3 explains some basics about transformer efficiency metrics and gives the two main equations used to define efficiency: one for IEC in terms of power input and a second for ANSI/IEEE in terms of power output. Either equation can be applied to the published requirements of distribution transformers where the countries establish maximum levels of no-load and load losses, to determine the percentage efficiency at any percentage loading point. Looking across the various programmes in the market, some economies regulate on

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the basis of 50% load, but others have 35% and 40% for certain groups and others have 85% of rated load: this is not perceived to be a major issue as the values can be adjusted using known mathematical formulae. The following options for a suitable metric will be further considered after data has been assimilated: a) Maximum no-load and load losses reported separately in watts of power loss. These would only enable comparison of the same kVA rating, voltage class and number of phases. b) Per cent efficiency according to the IEC definition at a particular rated loading point. These would only enable comparison of the same kVA rating, voltage class and number of phases. c) Per cent efficiency according to the ANSI/IEEE definition at a particular rated loading point. These would only enable comparison of the same kVA rating, voltage class and number of phases. d) Power loss index – a calculated ratio of losses for the power throughput of a transformer, possibly combined with the maximum efficiency to derive a power-loss index calculated at a peak efficiency point for each kVA rating (requires investigation of relationship between losses and power through-put, if it scales with KVA rating which may need correction to make them comparable). This metric requires some analysis to determine the constraints around its application and whether it would constitute a more flexible and comparable metric than the other options. The Annex also expects the SEAD transformers research team to complete its comparative review of the global efficiency programmes in August 2013, which will provide further evidence to take into account regarding these options. It is likely that the most appropriate metric to use will be to compare the maximum losses associated with the transformers at 50% rated load and using the IEC-based definition of efficiency. However, comments are invited from participants and further evidence will be considered as data is assimilated. Regardless of the eventual metric used, data should be gathered including maximum watts of core and coil loss, because from these two measures of performance all the other metrics of comparison can be calculated. 

Proposal: To gather data from Annex Member States with maximum losses of core and coil losses and where possible the percentage efficiency level at a given loading, and from that the analytical team will study the available data and develop the best metrics for comparison across the economies.

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6 Market Segmentation for Benchmarking by Product Application In general, comparison of raw overall average efficiencies or loss figures across the different markets makes little sense. It is important first to isolate products applicable to a certain application and for which comparison will carry some engineering and policy significance. In line with the principles of the Mapping and Benchmarking Framework document, segmentation avoids technology-specific features (dry vs. oil filled, copper vs. aluminium coils for example). This should mean that innovative or alternative approaches applied in any given region should be compared on an equal footing with conventional solutions for a given application. Efficiency figures as declared under the various national programmes are not comparable mainly due to differences in: 1. 2. 3. 4.

Type of transformer (liquid-filled vs. dry-type) kVA rating of the transformer (including IEC vs. ANSI/IEEE definition) Number of phases (single vs. three phase) Voltage class / BIL rating

Segmentation of data is therefore needed for each of these aspects. In addition, end use/application is a potential further aspect on which to segment, as that will have a significant influence on the purchase specification, not least from an economic perspective. Distribution transformers tend to be bought by electric utilities and commercial and industrial users: 



Electricity utilities tend to purchase their distribution transformers directly from manufacturers, specifying their desired features and performance. There are also utilities, such as some rural cooperatives and municipalities that make transformer purchases through electrical distributors and wholesalers. The supply chain for commercial and industrial customers can be complex, working through intermediaries such as stocking distributors and electrical contractors. Electrical contractors typically purchase transformers using specifications written by themselves or by agents. Some larger industrial customers buy transformers directly from distributors or manufacturers based on specifications drafted by in-house experts. Any large-volume or custom-order purchases made (e.g., orders from the petrochemical or the pulp and paper industry) are typically made directly with transformer manufacturers. Similarly, original equipment manufacturers (OEMs) know the exact specification they require for their finished products and typically work directly with manufacturers when placing an order.

When placing orders, the utilities and commercial and industrial customers tend to know the expected loading points these transformers will experience, and/or will be making a purchase based on projected load or around safety requirements and in-house policies and specification practices around spare transformer capacity. This will inevitably affect the average efficiency of the transformers purchased. Scope for segmentation is inevitably limited by data availability: final decisions on segmentation will have to be made once all data has been collected.

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

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Proposal: Data to be split by type (liquid/dry); by kVA rating (segments to be determined); by number of phases (single / three); by voltage class (segments to be determined). In addition, data on the end-user / specifier or intended application will be sought (utility / industrial etc.). Final segmentation to be determined once data has been assimilated.

7 Test Methodologies The most widely used test method today for measuring distribution transformers is based on the International Electrotechnical Commission (IEC) 60076 series of test standards, which are continually updated by the various committees and subcommittees working on these standards. The following section provides a summary of the IEC 60076 family of test standards. The following test methodologies have been identified that are likely to be used by participants for data to be submitted. Note that analysis of these test methodologies has not been completed, pending input from participating countries: International: 1. I IEC 60076-1 ed3.0 (2011-04) - Power transformers - Part 1: General 2. IEC 60076-11 ed1.0 (2004-05) - Power transformers - Part 11: Dry-type transformers EU9: 3. EN 50464-1:2007 - Three-phase oil-immersed distribution transformers, 50 Hz. For oil filled distribution transformers, the European standard (EN 50464-1) -load losses (Eo, Do, Co, Bo, Ao), and minimum performance levels. 4. EN 50541-1: 2011 - Three-phase dry-type distribution transformers, 50Hz (this superseded harmonised document HD 538). Canada: 5. CSA-C802.1-00, Minimum Efficiency Values for Liquid-Filled Distribution Transformers. This Standard provides minimum efficiency values derived from those defined for liquid- filled distribution transformers in NEMA Standard TP 1. 6. CAN/CSA C802.206 - Minimum Efficiency Values for Dry-Type Transformers 7. NEMA TP 2-2005 - Standard Test Method for Measuring the Energy Consumption of Distribution Transformers USA: 8. DOE published a final rule test procedure for distribution transformers.71 FR 24972 (April 27, 2006). Australia: 9. AS 2374.1.2 - Power Transformers Part 1.2: Minimum Energy Performance Standard (MEPS) requirements for distribution transformers 10. AS 2735 - Dry-type power transformers 9

In Germany, power transformer designs for oil immersed power transformers from 3150 kVA to 80 MVA for 50Hz and rated voltage up to 123kV have maximum load and no load losses in DIN 42508:2009-08. However this does not cover the full range of European products.

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India: 11. IS 1180 (part I) Outdoor type three- phase distribution transformers up to and including 200 kVA, 11 kV – specification (India) 12. IS 2026 (part 2) Specifications of power transformers – for Temperature-rise China: 13. GB 1094.1-1996 (Power transformers – Part 1: General) 14. GB 1094.11-2007 (Power transformers – Part 11: Dry-type transformers). Further test methodologies may be identified with input from participants.

8 Normalisation of Data from Each Region There is a wide diversity of metrics used for establishing the minimum performance requirements. There are differences observed around maximum watts of core and coil losses (at a defined loading point), as well as percentage efficiency at different loading point and an exponential equation that is based on the transformer power rating. However, as noted above, if load and no-load losses are known and some other parameters, then the various metrics can be calculated and so these will not require normalisation. But there are also differences in how the transformer capacity is rated: 1. The IEC defines the transformer on the basis of input (i.e., including losses of the distribution transformer). For the measurement of losses, most economies that are active on distribution transformers use the IEC 60076 standard. In some cases, there are slight (local) modifications that have been made due to specific or unique requirements; however, for the most part the standards are consistent. The economies that fall into the group using or based on IEC 60076 are: Australia, Brazil, China, Europe, India, Israel, Japan, Korea, New Zealand and Vietnam. 2. IEEE/ANSI define capacity on the basis of output (i.e. excluding losses). Two major economies that use IEEE/ANSI are the United States and Canada. The US is using its own test standard that was developed between 1998 and 2006 by DOE in close consultation with manufacturers and other stakeholders. The US test standard is largely based on ANSI/IEEE C57.12.90. Canada has adopted the most recent voluntary industry testing standard, NEMA TP 2-2005 that is similar to the same ANSI/IEEE standard. Normalisation will have to be carried out for capacity before segmenting the transformer data for that parameter.

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9 Approach to the Data Analysis Final decisions will be made when data has been assimilated; the procedure is likely to be as outlined below: 1) Data preparation – each of the spreadsheets of distribution transformer data will be collated and merged into a single dataset with a consistent set of data fields. Where this is not possible, separate data fields will be maintained and careful notes taken to describe these differences. 2) Normalisation calculation – depending on the differences between the datasets, calculations will be performed to provide for a consistent, normalised set of performance results for analysis. This could include, for example, making a correction for the kVA rating, depending on whether it is reported based on the power input or the power output. 3) Metrics to be used for comparison – next, the metrics for comparison will be calculated for the database, selecting one of the metrics that are discussed in section 5 of this report. These will be finalised with input from the member states. 4) In order to maximise the intersection of the data provided, the M&B Annex Team may use the '0.75-scaling rule' to interpolate performance results from two adjoining kVA ratings in a given country to one that is common in other national markets. This rule relies on the relationship that for similarly designed transformers, costs of construction and losses scale to the ratio of kVA ratings raised to the 0.75 power. 5) Benchmarking graphs – the normalised, comparative transformers will then be plotted on graphs to illustrate the differences and enable users to review and understand the data. These graphs will be for a set of the most common kVA ratings. 6) Time series – depending on the availability of time series data, the analysis will include this same review for a series of data points starting as early as 1980 and looking at five year increments up to the most recent year. 7) Uncertainties – there are many uncertainties that will need to be carefully considered, including the integrity of the normalisation calculation, the equivalency of the 50 and 60Hz systems, and the representativeness of the metric chosen for comparison. These and other uncertainties encountered in performing the data analysis will be evaluated as far as possible.

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10 Data Sources Some counties have made indicative replies on data availability; to these are added some initial suggestions for alternative sources that could be approached if deemed appropriate by the participant country: Australia (data enquiry reply received)  Submission of data possible from Appliance Energy Efficiency Branch, Department of Resources, Energy and Tourism  Data downloaded from Government registry database http://reg.energyrating.gov.au/comparator/product_types/38/search/  Alternatives possible: One or more electric utilities, manufacturer(s) Canada (data enquiry reply received)  Submission of bespoke data possible from Natural Resources Canada  Data downloaded from Natural Resources Canada (published data set, 5,852 products, from http://oee.nrcan.gc.ca/pml-lmp/index.cfm?action=app.searchrecherche&appliance=TRANS_DRY)  Alternatives possible: Electrofederation of Canada (manufacturers association); utilities such as Hydro Quebec, Ontario Hydro, British Columbia Hydro UK (initial indicative reply received)  Department of Environment, Food and Rural Affairs is currently collating data; may be able to supply data at some future tie but none available at present.  Alternatives possible: UK National Grid; utilities (EDF, Scottish and Southern, Eon) China (contact established with International Copper Association China office)  International Copper Association China office - some data likely to be available.  Alternatives possible: National Development and Reform Commission (NDRC); CLASP-China. India (contact established with International Copper Association India office):  International Copper Association - India office - some data likely to be available.  Bureau of Energy Efficiency will be approached to ask.  Alternatives possible: Central Electricity Authority. Countries from which no reply has been received: USA (contact identified within DOE)  Possible information from US Department of Energy, Codes and Standards Research Team.  Alternatives possible: National Electrical Manufacturers Association; utilities (e.g. PG&E, SCE, TVA); manufacturers (e.g. Howard Industries, Cooper, ABB). EU 

Alternatives possible: CEN/CENELEC Working Group formed by DG ENTR; transformers ecodesign regulation preparatory study report.

Other IEA 4E countries for which no reply has been received and for which alternative sources have not been identified: Austria, Denmark, France, Japan, Republic of Korea, Switzerland.

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11 Data Requirements Participants are asked to provide at least the following information for each of the transformers: A. B. C. D. E. F. G. H.

Transformer type and description, with any available features Number of phases (1 or 3) Operating frequency (50Hz or 60Hz) kVA rating and whether it is based on the input rated power (IEC) or output (ANSI/IEEE) Voltage rating of the high-voltage winding Voltage rating of the low-voltage winding The no-load (i.e., core steel and stray) losses (W) The load-losses (i.e., winding losses) at rated load (W), plus confirming the rated load (%) at which this is measured

Useful but not essential information: I. The design temperature rise of the windings in degrees Celsius J. Tap range – whether the transformer has taps, and if so, the range from highest to lowest Distribution transformer performance data is invited mainly for 2010-2012, and also historical data extending back to around 1980 in order to generate a meaningful time series. Information on stock and sales For years available between 1980 and 2012: K. Total national stock of products in service (in thousands of products), broken down by type and application sector as available L. Total national annual sales (in thousands of products), broken down by type and by application sector as available Additional Information Required for Data Processing M. Test methodology(ies) used to derive the data, and any relationship to known international standards N. Dates at which any changes to test methods occurred during period of reported data O. List of local regulations that define and affect product efficiency. Additional Information Required for Other Planned Analysis P. Summary of all major policy actions affecting transformers over the period data is available including whether voluntary or mandatory, the year when policy was first considered, the year of formal announcement of the policy plans, and the year when the policy came into force Q. Summary of any cultural or other issues that are thought to affect this product at the local level.

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Appendix 1: Indicative relative levels of ambition for transformer policies This section is based on interim analysis under the SEAD transformers project. The final report was due for publication after this section was completed. A preliminary comparison of the regulatory requirements from the various economies with MEPS and efficiency programmes has been published by the SEAD project. This research project is still in draft, however the draft results demonstrate that it is possible to compare the different regulatory programmes and that there is generally a similar degree of performance / ambition between them. Figure A1 below presents the levels of ambition associated with the liquid-filled distribution transformer efficiency programmes. The level of ambition is presented as a percentage efficiency at 50% of rated load, 50Hz network frequency and using the IEC definition of a kVA rating (i.e., based on power input). These curves are primarily of the MEPS curves (with the exception of India’s 3-Star and Europe’s AoCk), and they generally show that all the countries are clustered together within approximately 0.4% on the efficiency scale at any given kVA rating, with the exception of Korea, which has adopted a MEPS level that is lower than the other countries. The highest level of ambition in MEPS is the curve for the new US DOE MEPS that will take effect in 2016. Some of the country curves have anomalies in how they treat losses, such as Israel at 800 kVA and Mexico at 200 kVA. The shape of these two curves is unexpected because the inherent physics of a transformer enables efficiency to improve with higher kVA ratings; therefore to have the level drop while increasing in kVA rating is unusual. At 100 kVA, the existing efficiency requirements range from 97.96% to 98.96%, with a new level of ambition adopted by US DOE for 2016 raising the requirement at 100 kVA above 98.9% (after making adjustments for 50Hz operation and the IEC definition of efficiency).

Figure A2 below presents the levels of ambition associated with the dry-type distribution transformer efficiency programmes. The level of ambition is presented as a percentage efficiency at 50% of rated load, 50Hz network frequency and using the IEC definition of a kVA rating (i.e., based on power input). These curves are primarily dry-type distribution transformer MEPS curves (with the exception of Europe’s BoBk), and they generally show that all the countries are clustered together within approximately 0.5% on the efficiency scale at any given kVA rating. Korea has the lowest MEPS requirements in dry-type, as is the case with liquid-filled, however Korea’s level of ambition is not as low on the dry-type relative to the other countries as it is for the liquidfilled. The highest level of ambition in MEPS is the curve for China and the new US DOE MEPS that will take effect in 2016. These two curves are largely the same as the European voluntary level considered for dry-type, BoBk. At 100 kVA, the existing efficiency requirements range from 97.80% to 98.32%.

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Product Definition: Distribution Transformers

Version 1: 8 October 2013

Figure A1. Efficiency at 50% Load for MEPS Requirements on Three-Phase LiquidFilled Transformers (Log Scale)

Figure A2. Efficiency at 50% Load for Three-Phase Dry-Type Distribution Transformers (Log Scale)

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Appendix 2: Derivation of indicative efficiency conversion factors between 50Hz and 60Hz transformers Whether a transformer is manufactured to operate at 50Hz, 60Hz or some other frequency is determined at the design stage. In Japan there are electrical distribution networks that operate at both frequencies (50Hz and 60Hz) and comparison of the requirements of the Top Runner programme that covers both has been used to provide some insight into the relative performance. The Top Runner programme was designed to establish an equivalent performance requirement nationally, on both the 50Hz and 60Hz systems in Japan. By comparing the equations that were developed and taking the average of the difference between them, a multiplier can be developed that shows the performance difference between transformers designed for 50Hz and those designed for 60Hz in the same national market. The difference in performance is small, however it does find that the 50Hz units are slightly less efficient than the 60Hz units. Figure A3 below illustrates the curves associated with the requirements of oil-filled distribution transformers.

Figure A3. Plot of Japanese Top Runner Requirements for Liquid-Filled Transformers

The Top Runner programme has similar requirements for dry-type transformers (cast coil), and now there are two new proposed updates – one with more ambition than the other. Overall, there are six different product groups from three different levels of ambition (one is the existing Top Runner programme and the other two are the proposed updates under consideration). The table below shows the ratio of 50Hz transformers of the same kVA rating Page 23 of 26

Product Definition: Distribution Transformers

Version 1: 8 October 2013

to 60Hz transformers, effectively creating the ‘normalisation’ factor for converting from 60Hz efficiency requirements to their equivalent in a 50Hz market for comparison. Change % efficiency Oil-filled

Dry-Type

Phase

kVA Rating

Single Three Three Single Three Three

All 500 KVA All 500 KVA

Top Runner (50/60Hz) 0.99960 0.99939 0.99971 1.00002 1.00032 1.00005

Proposal (50/60Hz) 0.99969 0.99955 0.99957 0.99981 1.00008 0.99986

1

Proposal (50/60Hz) 0.99969 0.99959 0.99955 0.99983 1.00005 0.99985

2

The conversion factor for oil-filled transformers is 0.99959 and for dry-type transformers is 0.99999. These values are multiplied by the 60Hz efficiency values at 50% loading to convert them to the equivalent performance at 50Hz.

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Product Definition: Distribution Transformers

Appendix 3: transformers

Version 1: 8 October 2013

Efficiency

metrics

for

Efficiency is a measure of the power consumed by a transformer, and it is determined in part by the sum of the core losses and winding losses experienced by the transformer. The efficiency of a transformer varies across the range of loading points that a transformer may experience in its lifetime. The measured efficiency of a transformer operating at 80% of rated load (where winding losses are likely to dominate) will probably be different to the efficiency of a transformer operating at 20% of rated load (where core losses are likely to dominate). Figure A4 (for a three-phase 75 kVA dry-type transformer) shows the efficiency curve relative to the watts of core and winding loss. This figure shows that the efficiency curve varies over the loading points, with its peak occurring where the core losses are equal to the winding losses.

Figure A4. Illustration of Relationship Between Losses and Efficiency

Maximum losses can be converted into percentage efficiency at a specified loading point (50% for this report) by applying the IEC formula for percentage efficiency. The equation that can be used is given below:

Expands to become:

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Product Definition: Distribution Transformers

Version 1: 8 October 2013

Where:

LoadPU – represents the per unit loading experienced by the transformer (usually as a percentage, such as 40%, 50% or 80% load. For normalisation purposes in this report, 50% is used. SkVA – represents the kVA rating of the transformer, such as 50kVA, 100KVA or 2500kVA. NL – represents the kilowatts of loss in the core of the transformer (to be consistent with the units in the power input calculation). LL – represents the kilowatts of loss in the winding (i.e., coil) of the transformer. A similar equation is used for determining efficiency for those transformers that are covered under the ANSI/IEEE testing standards, as shown below:

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