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How does a UPS transformer’s efficiency affect the overall system efficiency?

ASHRAE 90.4 Section 6.2.1.2.1.1 notes that UPS transformer’s efficiencies at given loads must be included in the total losses for evaluation. Active single feed systems should be evaluated at 100% and 50% ITE load while active dual feed systems should be evaluated at 50% and 25% loads.

  • Are there any transformers exempt from this legislation?

      As defined by DOE 10 CFR 431.192 a Distribution transformer means a transformer that—

      • Has an input voltage of 34.5 kV or less;
      • Has an output voltage of 600 V or less;
      • Is rated for operation at a frequency of 60 Hz; and
      • Has a capacity of 10 kVA to 2500 kVA for liquid-immersed units and 15 kVA to 2500 kVA for dry-type units.

      These are the transformers subjected to the DOE 2016 requirements.

      Exceptions are defined by the same DOE 10 CFR 431.192.(5):

      • The term “distribution transformer” does not include a transformer that is an:
      1. Autotransformer;
      2. Drive (isolation) transformer;
      3. Grounding transformer;
      4. Machine-tool (control) transformer;
      5. Non-ventilated transformer;
      6. Rectifier transformer;
      7. Regulating transformer;
      8. Sealed transformer;
      9. Special-impedance transformer;
      10. Testing transformer;
      11. Transformer with tap range of 20 percent or more;
      12. Uninterruptible power supply transformer; or
      13. Welding transformer.

      Drive (isolation) transformer means a transformer that:

      1. Isolates an electric motor from the line;
      2. Accommodates the added loads of drive-created harmonics; and
      3. Is designed to withstand the additional mechanical stresses resulting from an alternating current adjustable frequency motor drive or a direct current motor drive.

  • What are the types of transformers affected by DOE 2016 and NRCan 2019?
  • What are the Energy Efficiency levels mandated by DOE as of January 1st 2016?

      The US Department of Energy (DOE) has regulated the energy efficiency level of low-voltage (LV) dry-type distribution transformers in US since 2007, and liquid-immersed and medium-voltage (MV) dry-type distribution transformers since 2010.

      DOE’s CFR (Code of Federal Regulation) title 10, part 431 defines the current energy efficiency standards for distribution transformers sold in US also known as TP1 energy efficiency levels as adopted by NEMA. Effective Jan. 1st 2016 DOE’s CFR 10 p.431 will require new higher levels of Energy Efficiency for transformers installed in any US territory as published in the Federal Register Vol. 78, No. 75 on April 18, 2013.

      Any Distribution transformer manufactured on or after Jan. 1st 2016 and sold in any US state will have to comply with the new energy efficiency levels defined by this document.

      Q2: What are the types of transformers affected?

      The three types of distribution transformers covered by the standard are: low-voltage dry-type, liquid-immersed, and medium-voltage dry-type distribution transformers.

      Q3: What are the Energy Efficiency levels mandated by DOE as of January 1st 2016?

      The new Energy Efficiency levels mandated as of Jan.1st 2016 are as follows:

      Amended Energy Conservation Standards for Low-Voltage Dry-Type Distribution Transformers

      Single phase   Three phase  
      kVA Efficiency (%) kVA Efficiency (%)
      15 97.7 15 97.89
      25 98 30 98.23
      37.5 98.2 45 98.4
      50 98.3 75 98.6
      75 98.5 112.5 98.74
      100 98.6 150 98.83
      167 98.7 225 98.94
      250 98.8 300 99.02
      333 98.9 500 99.14
          750 99.23
          1000 99.28
      Note: All efficiency values are at 35 percent of nameplate-rated load, determined according to the DOE Test Method for Measuring the Energy Consumption of Distribution Transformers under Appendix A to Subpart K of 10 CFR part 431.

      Bottom of Form

       

       

      Amended Energy Conservation Standards for Medium-Voltage Dry-Type Distribution Transformers

      Single phase       Three phase      
      BIL* kVA 20–45 kV efficiency (%) 46–95 kV efficiency (%) 96 kV efficiency (%) BIL kVA 20–45 kV efficiency (%) 46–95 kV efficiency (%) 96 kV efficiency (%
      15 98.1 97.86 15 97.5 97.18
      25 98.33 98.12 30 97.9 97.63
      37.5 98.49 98.3 45 98.1 97.86
      50 98.6 98.42 75 98.33 98.13
      75 98.73 98.57 98.53 112.5 98.52 98.36
      100 98.82 98.67 98.63 150 98.65 98.51
      167 98.96 98.83 98.8 225 98.82 98.69 98.57
      250 99.07 98.95 98.91 300 98.93 98.81 98.69
      333 99.14 99.03 98.99 500 99.09 98.99 98.89
      500 99.22 99.12 99.09 750 99.21 99.12 99.02
      667 99.27 99.18 99.15 1000 99.28 99.2 99.11
      833 99.31 99.23 99.2 1500 99.37 99.3 99.21
              2000 99.43 99.36 99.28

      Bottom of Form

              2500 99.47 99.41 99.33
      BIL means basic impulse insulation level              
      Note: All efficiency values are at 50 percent of nameplate rated load, determined according to the DOE Test Method for Measuring the Energy Consumption of Distribution Transformers under Appendix A to Subpart K of 10 CFR part 431.

      Bottom of Form

                   

  • Can I still sell my C802.2 efficiency transformers that I have in stock after NRCan 2019
  • What are the environmental benefits of this change?

      According to DOE, the new amendments to the existing efficiency standards would further decrease electrical losses by about 8 percent for liquid-immersed transformers, 13 percent for medium-voltage dry-type transformers, and 18 percent for low-voltage dry-type transformers. In addition, about 264.7 million metric tons of carbon dioxide emissions will be avoided, equivalent to the annual greenhouse gas emissions of about 51.75 million automobiles.

      Beginning in 2016, newly amended energy efficiency standards for distribution transformers will save up to $12.9 billion in total costs to consumers — ultimately saving families and businesses money while also reducing energy consumption. The new distribution transformer standards will also save 3.63 quadrillion British thermal units of energy for equipment sold over the 30-year period of 2016 to 2045.

  • What is the energy efficiency regulation compliance in the U.S. and Canada?

      In the past several years, there has been an accelerated rate of change in updating energy efficiency standards for transformers in North America.

      Governments in US and Canada are encouraging users to use higher energy efficiency dry-type transformers, to help reduce carbon dioxide emissions. There is also a long term cost savings in operating higher efficiency transformers translated in lower energy usage, lower cooling cost, etc.

      In U.S.A. the Department of Energy (DOE) has mandated new higher efficiency levels effective Jan. 1st 2016.

      In Canada Natural Resources Canada (NRCan) published SOR/2016-311 which amends the Energy Efficiency Act to align the via amendment 14 the minimum energy efficiency levels for dry type transformers to the ones implemented by DOE in Jan 2016.

      The new NRCan 2019 regulation is going to be enforced across Canada on May 1st, 2019. The Ontario government already adopted these new efficiency levels by publishing the ON Reg.404-12 which in schedule 6 defines the new energy efficiency levels that dry type transformers sold in ON must comply with starting Jan.1st 2018 (Ontario Energy Efficiency Compliance).

      The rest of Canada (including Quebec) is still following the current energy efficiency levels prescribed by CSA C802.2, until the new NRCan regulations come in effect on May 1st 2019.

      To help our valued customers in estimating the cost savings resulting from upgrading their old dry type transformer to the new DOE2016/NRCan2019 efficiency levels, HPS has developed an Energy Savings Calculator available on its website. To find out how HPS can help reduce your energy consumption, click here.

      To visit the Canadian Gazette for more information about the Canadian energy efficiency standards, click here.

      For the Ontario Energy efficiency regulation please click here.

      To view an electronic copy of the U.S. DOE energy efficient standards, click here.

  • Will NEMA Premium transformers continue to be offered?
  • What are the new Energy Efficiency levels in place for the Canada in 2019?

      Transformers have been and remain an essential part of our electrical infrastructure. Everywhere we look there is a transformer supplying power to industrial, commercial or residential applications.

      In the past decades the greenhouse gas emissions and the effects on our planet have become the focus of many governments, agencies and individuals. Energy generation is a major contributor to the greenhouse gas emissions. In addition to widespread efforts to make energy generation more environmentally friendly, there is also a goal to lower energy consumption within most industrial, commercial and residential areas. Achieving increased energy efficiency levels for equipment and consumer products has become a priority for many manufacturers.

      Improving the energy efficiency of new transformers is a primary goal of the Department of Natural Resources (French: Ministère des Ressources naturelles), operating under the FIP applied title Natural Resources Canada (NRCan). It has the legal authority to define efficiency levels and enforce compliance. Environmentally conscious consumers also recognize that buying a higher energy efficiency transformer will have a societal payback over many years.

      NRCan has established new and more stringent Energy Efficiency levels for Transformers in Canada effective May 1st, 2019 that is generically referred to as NRCan 2019. The new efficiency levels for Medium Voltage Liquid-Filled, Medium Voltage and Low Voltage Dry-Type Distribution Transformers are defined byNRCan and largely follow the U.S.A.’s efficiency leves in the DOE’s 2016 CFR (Code of Federal Regulations) title 10 part 431. The new efficiency levels are expected to reduce energy losses by an average of 18% in low-voltage dry-type distribution transformers and 13% for medium-voltage dry-type transformers, over the current C802.2 efficiency levels.

      To put the benefits of this change in perspective, the U.S.A’s DOE projects savings up to $12.9 billion (U.S.) in total costs to consumers and 3.63 quadrillion Btu of energy over a 30 year period. In addition, about 265 million metric tons of carbon dioxide emissions will be avoided, equivalent to the annual greenhouse gas emissions of about 52 million automobiles. Canada can expect similar benefits but scaled to Canada’s overall economy.

      The subject of energy efficiency for transformers raises two main considerations:

      (1) Under normal operation a transformer is always on (typically at 35% average loading), making any energy efficiency improvements more significant over an extended period of time. This means that customers will be rewarded in two manners: they are reducing greenhouse gas emissions and there is an economic payback through reduced energy costs.? Considering the life expectancy of a transformer and the fact that the transformer will be on 24 hours a day, 7 days a week for the next 25-30 years, even small energy efficiency improvements will pay dividends for decades.? A secondary benefit is that more efficient transformers generate less heat, and in many cases this translates into lower costs to cool the environment in which they are utilized.

      (2) The currently mandated energy efficiency levels are already hovering around the 98-99% mark, depending on the type of transformer and ratings. This means that any further efficiency improvements become more challenging to achieve, typically requiring more and/or better core and conductor materials.? This will directly impact the cost of the transformer in most cases. However, as noted in point 1 above, there is an economic benefit to offset the higher initial transformer costs. The new NRCan 2019 compliant transformers that will come on the market will also be somewhat heavier than the current C802.2 efficiency level transformers.

      Hammond Power Solutions (HPS) has an online Energy Savings Calculator to help to our customers determine the savings they can achieve by installing a higher efficiency transformer.? It includes a comparison of transformers with older efficiencies to those of higher efficiency (NRCan 2019 and DOE 2016) as well as specifics of the application and the customer’s cost of energy.

      The Electricity savings resulting from upgrading one three phase 75 kVA transformer can be translated into one of the following:

      • 1.19 Metric Tons of CO2
      • 121 Gallons of Gasoline
      • About 1/6th of the energy used by an average household annually
      • Planting 28 Trees
      • 0.9 Acres of Forest
      • Recycling 0.34 Metric Tons of Waste
      • Savings of $166 per year at $0.12 per kW-Hr

      Dense Forest

      At some kVA ratings NEMA Premium energy efficiency levels meet or slightly exceed the DOE 2016 levels, some are slightly below the new requirements.? However, the NEMA Premium products are optional within the market today, and many consumers do not take advantage of the benefits they afford.? Hence, the DOE will require that all transformers manufactured after January 1st, 2016 will meet the new efficiency levels.

      The environmental impact and savings for our customers resulting from the DOE changes are positive and significant.? HPS fully embraces and supports this change, and the environmental benefits our society will receive as a result.? We proudly offer high quality transformers meeting the most stringent Energy efficiency requirements today and will be in a position to support the migration to the new DOE 2016 higher-efficiency designs for our valued partners and customers, beginning in the latter half of 2015.

      View HPS Transformer Savings Analyzer.

  • Did the DOE 2016 and NRCan 2019 efficiency regulations result in product brand changes for HPS?

      The obsolete HPS TP1/C802.2 rated Sentinel, Synergy, Centurion and Express lines were still available in the Canadian until the NRCan 2019 efficiency levels (same as DOE 2016) were mandated. In addition the older medium voltage Millennium line was still available in Canada until NRCan 2019 May 1st, 2019.

      The older lines were replaced with DOE 2016 and NRCan 2019 compliant low voltage Sentinal G (general purpose), Sentinel K (K rated), Sentinel H (harmonic mitigation) Express G and Tribune E (DIT, Canada only) product lines. In addition the medium voltage Millennium G, Millennium E and EnduraCoil lines also meet the updated DOE 2016 and NRCan 2019 efficiency levels. While exempt from regulations, the Titan N encapsulated transformers often meet or exceed the DOE 2016 and NRCan 2019 regulations.

  • How will the new DOE 2016 and NRCan 2019 compliant Sentinel G, K and H be different from the older TP1/C802.2 lines?
  • What should I do if I need to quote a project that will ship after NRCan 2019 is implemented?
  • Can I still sell my TP1 efficiency transformers that I have in stock?
  • Can I increase the kVA rating of an existing transformer?

      The most common way to increase the available kVA rating of an existing transformer is to add additional fan cooling. This typically requires modifications including raising the transformers core, adding fans and fan brackets, a motor power supply and controls to start fan cooling when the transformer’s components reach a preset temperature. Fans should never be added without contacting and following specific instructions from the manufacturer. Low temperature rise transformers (115C and 80C rise with 220C insulation) can maintain higher loads in lower ambient transformers. Always follow proper ventilation and clearance instructions.

  • Will current TP1 Distribution efficiency units be available into Q4/2015 and Q1/2016?

      The supply will be hard to predict.  Many manufacturers will stop production of these units well before January 1st 2016.

      • Supply channel may be hesitant to stock the current TP1 units if specifications are largely updated to support the new regulations.
      • Manufacturers will establish cut-offs for stock replenishment and custom orders 2-5 months before January 1st, 2016.

  • What is an exciting or excitation current?

      A transformer exciting current is the current or amperes required to energize the core. Even with zero load, a transformer will draw a small amount of current due to internal loss. The excitation current is made up of two components. The real component in the form of losses that are commonly referred to as no-load losses. The second form is reactive power measured in KVAR.

  • What are Energy Efficient (TP1) Transformers?

      TP1 was often used to generically refer to the minimim efficiency levels that were originally require in Canada in 2005 and in the U.S. in 2006 for low voltage ventilated transformers. Specifically, the TP1 specification covers energy efficiency in transformers based on the NEMA Standards Publication, TP-1-1996, “Guide for Determining Energy Efficiency for Distribution Transformers”. The TP1’s recomendations did consider the total owning cost of ownership unique for industrial or commercial installations. TP1 is measured per TP2 and displayed on the nameplate per TP3.

      The TP1 specifcations have now been replaced by higher efficiency specifications:

      • U.S.A.: DOE 2016 efficiency levels (January 1st, 2016)
      • Canada: NRCan 2019 efficiency levels (May 1st, 2019)

  • What is the “Efficiency” of a transformer?
  • Shunt reactor – definition
  • What is NEMA TP2?

      NEMA TP2 defines how energy efficiency is measured. Typically, it uses a sinusoidal wave with no harmonics at unity (1.0) power factor at 35% load for 600 volt class units and 50% load for medium voltage units.

      This regulation has been replaced by similar test standards described in DOE 2016 and NRCan 2019 regulations.

  • What is NEMA TP3?
  • Are obsolete TP1/C802.2 transformers still available in North America?

      TP1 transformers built and in the U.S.A. before January 1st, 2016 can still be sold and installed in the U.S.A. At the time of this writing, stocks of new TP1 transformers are no longer readily available but may still be found in the used market.

      In Canada, NRCan 2019 will ban manufacturers from selling transformers after May 1st, 2019 which don’t meet the new 2019 efficiency regulations. Older C802.2 units can still be sold by distributors and installed after the regulations.

  • What are the new Energy Efficiency levels coming for Transformers sold in the U.S.?

      Transformers have been and remain an essential part of our electrical infrastructure.  Everywhere we look there is a transformer supplying power to industrial, commercial or residential applications.

      In the past decades the greenhouse gas emissions and the effects on our planet have become the focus of many governments, agencies and individuals. Energy generation is a major contributor to the greenhouse gas emissions. In addition to widespread efforts to make energy generation more environmentally friendly, there is also a goal to lower energy consumption within most industrial, commercial and residential areas. Achieving increased energy efficiency levels for equipment and consumer products has become a priority for many manufacturers.

      Improving the energy efficiency of new transformers is a primary goal of the US Department of Energy (DOE), and they have the legal authority to define efficiency levels and enforce compliance.  Environmentally conscious consumers also recognize that buying a higher energy efficiency transformer will have a societal payback over many years.

      The Department of Energy has established new and more stringent Energy Efficiency levels for Transformers in the U.S. effective January 1st 2016.  The new efficiency levels for Medium Voltage Liquid-Filled, Medium Voltage and Low Voltage Dry-Type Distribution Transformers are defined in DOE’s CFR (Code of Federal Regulations) title 10 part 431.  Widely known as DOE 10 CFR p431, it was published in the Federal Register Vol. 78, No. 75 on Thursday April 18, 2013.  According to the DOE, the new efficiency levels are expected to reduce energy losses by an average of 18% in low-voltage dry-type distribution transformers and 13% for medium-voltage dry-type transformers, over the current TP-1 efficiency levels.

      To put the benefits of this change in perspective, the DOE projects savings up to $12.9 billion in total costs to consumers and 3.63 quadrillion Btu of energy over a 30 year period. In addition, about 265 million metric tons of carbon dioxide emissions will be avoided, equivalent to the annual greenhouse gas emissions of about 52 million automobiles.

      The subject of energy efficiency for transformers raises two main considerations:

      1. Under normal operation a transformer is always on (typically at 35% average loading), making any energy efficiency improvements more significant over an extended period of time.  This means that customers will be rewarded in two manners:  they are reducing greenhouse gas emissions and there is an economic payback through reduced energy costs.  Considering the life expectancy of a transformer and the fact that the transformer will be on 24 hours a day, 7 days a week for the next 25-30 years, even small energy efficiency improvements will pay dividends for decades.  A secondary benefit is that more efficient transformers generate less heat, and in many cases this translates into lower costs to cool the environment in which they are utilized.
      2. The currently mandated energy efficiency levels are already hovering around the 98-99% mark, depending on the type of transformer and ratings.  This means that any further efficiency improvements become more challenging to achieve, typically requiring more and/or better core and conductor materials.  This will directly impact the cost of the transformer in most cases.  However, as noted in point 1 above, there is an economic benefit to offset the higher initial transformer costs.  The new DOE 2016 compliant transformers that will come on the market will also be somewhat heavier than the current TP-1 efficiency level transformers.

      Hammond Power Solutions (HPS) has an online Energy Savings Calculator to help to our customers determine the savings they can achieve by installing a higher efficiency transformer.  It includes a comparison of transformers with older efficiencies to those of higher efficiency (TP1, NEMA Premium and DOE 2016 in the future) as well as specifics of the application and the customer’s cost of energy.

      Currently, for applications that require higher energy efficiency than the DOE regulated TP-1 levels, industry is using Premium Efficiency transformers defined by the NEMA Premium Efficiency Guidelines that stipulate approximately 30% lower loses than the TP-1 levels.  In terms of the environmental benefits of using a NEMA Premium transformer over a TP-1 rated let’s look at an example:

      The Electricity savings resulting from upgrading one three phase 75 kVA transformer can be translated into one of the following:

      • 1.19 Metric Tons of CO2
      • 121 Gallons of Gasoline
      • About 1/6th of the energy used by an average household annually
      • Planting 28 Trees
      • 0.9 Acres of Forest
      • Recycling 0.34 Metric Tons of Waste
      • Savings of $166 per year at $0.12 per kW-Hr

      Forest image 

      At some kVA ratings NEMA Premium energy efficiency levels meet or slightly exceed the DOE 2016 levels, some are slightly below the new requirements.  However, the NEMA Premium products are optional within the market today, and many consumers do not take advantage of the benefits they afford.  Hence, the DOE will require that all transformers manufactured after January 1st, 2016 will meet the new efficiency levels.

      The environmental impact and savings for our customers resulting from the DOE changes are positive and significant.  HPS fully embraces and supports this change, and the environmental benefits our society will receive as a result.  We proudly offer high quality transformers meeting the most stringent Energy efficiency requirements today and will be in a position to support the migration to the new DOE 2016 higher-efficiency designs for our valued partners and customers, beginning in the latter half of 2015.

  • New Energy Efficiency levels US 2016

      Transformers have been and remain an essential part of our electrical infrastructure.  Everywhere we look there is a transformer supplying power to industrial, commercial or residential applications.

      In the past decades the greenhouse gas emissions and the effects on our planet have become the focus of many governments, agencies and individuals. Energy generation is a major contributor to the greenhouse gas emissions. In addition to widespread efforts to make energy generation more environmentally friendly, there is also a goal to lower energy consumption within most industrial, commercial and residential areas. Achieving increased energy efficiency levels for equipment and consumer products has become a priority for many manufacturers.

      Improving the energy efficiency of new transformers is a primary goal of the US Department of Energy (DOE), and they have the legal authority to define efficiency levels and enforce compliance.  Environmentally conscious consumers also recognize that buying a higher energy efficiency transformer will have a societal payback over many years.

      The Department of Energy has established new and more stringent Energy Efficiency levels for Transformers in the U.S. effective January 1st 2016.  The new efficiency levels for Medium Voltage Liquid-Filled, Medium Voltage and Low Voltage Dry-Type Distribution Transformers are defined in DOE’s CFR (Code of Federal Regulations) title 10 part 431.  Widely known as DOE 10 CFR p431, it was published in the Federal Register Vol. 78, No. 75 on Thursday April 18, 2013.  According to the DOE, the new efficiency levels are expected to reduce energy losses by an average of 18% in low-voltage dry-type distribution transformers and 13% for medium-voltage dry-type transformers, over the current TP-1 efficiency levels.

      To put the benefits of this change in perspective, the DOE projects savings up to $12.9 billion in total costs to consumers and 3.63 quadrillion Btu of energy over a 30 year period. In addition, about 265 million metric tons of carbon dioxide emissions will be avoided, equivalent to the annual greenhouse gas emissions of about 52 million automobiles.

      The subject of energy efficiency for transformers raises two main considerations:

      (1) Under normal operation a transformer is always on (typically at 35% average loading), making any energy efficiency improvements more significant over an extended period of time.  This means that customers will be rewarded in two manners:  they are reducing greenhouse gas emissions and there is an economic payback through reduced energy costs.  Considering the life expectancy of a transformer and the fact that the transformer will be on 24 hours a day, 7 days a week for the next 25-30 years, even small energy efficiency improvements will pay dividends for decades.  A secondary benefit is that more efficient transformers generate less heat, and in many cases this translates into lower costs to cool the environment in which they are utilized.

      (2) The currently mandated energy efficiency levels are already hovering around the 98-99% mark, depending on the type of transformer and ratings.  This means that any further efficiency improvements become more challenging to achieve, typically requiring more and/or better core and conductor materials.  This will directly impact the cost of the transformer in most cases.  However, as noted in point 1 above, there is an economic benefit to offset the higher initial transformer costs.  The new DOE 2016 compliant transformers that will come on the market will also be somewhat heavier than the current TP-1 efficiency level transformers.

      Hammond Power Solutions (HPS) has an online Energy Savings Calculator to help to our customers determine the savings they can achieve by installing a higher efficiency transformer.  It includes a comparison of transformers with older efficiencies to those of higher efficiency (TP1, NEMA Premium and DOE 2016 in the future) as well as specifics of the application and the customer’s cost of energy.

      Currently, for applications that require higher energy efficiency than the DOE regulated TP-1 levels, industry is using Premium Efficiency transformers defined by the NEMA Premium Efficiency Guidelines that stipulate approximately 30% lower loses than the TP-1 levels.  In terms of the environmental benefits of using a NEMA Premium transformer over a TP-1 rated let’s look at an example:

      The Electricity savings resulting from upgrading one three phase 75 kVA transformer can be translated into one of the following:

      • 1.19 Metric Tons of CO2
      • 121 Gallons of Gasoline
      • About 1/6th of the energy used by an average household annually
      • Planting 28 Trees
      • 0.9 Acres of Forest
      • Recycling 0.34 Metric Tons of Waste
      • Savings of $166 per year at $0.12 per kW-Hr

      Dense Forest

       

      At some kVA ratings NEMA Premium energy efficiency levels meet or slightly exceed the DOE 2016 levels, some are slightly below the new requirements.  However, the NEMA Premium products are optional within the market today, and many consumers do not take advantage of the benefits they afford.  Hence, the DOE will require that all transformers manufactured after January 1st, 2016 will meet the new efficiency levels.

      The environmental impact and savings for our customers resulting from the DOE changes are positive and significant.  HPS fully embraces and supports this change, and the environmental benefits our society will receive as a result.  We proudly offer high quality transformers meeting the most stringent Energy efficiency requirements today and will be in a position to support the migration to the new DOE 2016 higher-efficiency designs for our valued partners and customers, beginning in the latter half of 2015.

  • How can I update my specification to include DOE 2016 compliant product?
  • What is DOE 2016 and how will it affect me?

      The US Department of Energy (DOE) has regulated the energy efficiency level of low-voltage (LV) dry-type distribution transformers in US since 2007, and liquid-immersed and medium-voltage (MV) dry-type distribution transformers since 2010.

      DOE’s CFR (Code of Federal Regulation) title 10, part 431 defines the current energy efficiency standards for distribution transformers sold in US also known as TP1 energy efficiency levels as adopted by NEMA. Effective Jan. 1st 2016 DOE’s CFR 10 p.431 will require new higher levels of Energy Efficiency for transformers installed in any US territory as published in the Federal Register Vol. 78, No. 75 on April 18, 2013.

      Any Distribution transformer manufactured on or after Jan. 1st 2016 and sold in any US state will have to comply with the new energy efficiency levels defined by this document.

  • How does a UPS transformer’s efficiency affect the overall system efficiency?

      ASHRAE 90.4 Section 6.2.1.2.1.1 notes that UPS transformer’s efficiencies at given loads must be included in the total losses for evaluation. Active single feed systems should be evaluated at 100% and 50% ITE load while active dual feed systems should be evaluated at 50% and 25% loads.

  • Are “Low Temperature Rise” transformers more efficient?

      One common misconception is that low temperature rise units are more efficient.

      While they usually have better efficiency at full load, it doesn’t guarantee that this will be the case at lower loads.

      Efficiency regulations typically use an average load of 35% to 50% when specifying efficiency. A low temperature rise transformer with more mass and surface area, but running with a low load may be less efficient and produce more heat than a standard transformer, while still maintaining a low overall temperature rise.

      Core loss for low temperature rise units are higher than a transformer with the same kVA rating, but a higher rise (present whenever unit is energized).

      Transformer temperature rise and efficiency should be regarded as two separate issues. If a high efficiency unit is desired, the TP1 (DOE 10 CFR Part 431), C802.2 (Canada) or NEMA Premium® energy efficient specifications should be noted. These regulations are all compatible with low temperature rise transformers.

  • Can I increase the efficiency of an existing transformer?

      There are two main loss area of a transformer, load losses in the coils and no-load losses in the core. Coil losses can only be lowered by completely replacing the coils and using a larger conductor which typically would not be compatible with existing core. In order to reduce core losses, better grades of steel and/or more advanced core design would require the complete replacement of the core while still reusing the coils. While possible, it’d typically be uneconomical to do except for large, custom transformers. The last option for increasing transformer efficiency is to provide line power meeting IEEE 519 THDi and/or removing harmonics on the load side before they reach the transformer.

      In most cases the most economical method to increase a transformer’s efficiency is to replace older transformers with modern high efficiency models meeting current North American efficiency requirements.

  • Can an Active Harmonic Filter be used to protect a specific circuit or machine in a building

      AHF’s are used to mitigate harmonics in a total circuit. Let’s set up an example. A company has 5 work cells and each is producing 20 amps of harmonics. A sixth work cell is introduced, it’s a different machine and it produces 30 amps of harmonics. Some operational issues on the new sixth machine have been determined to be caused by Power Quality issues. Can an AHF be deployed to just protect the new machine?

      • If the new machine is fed from a dedicated transformer, it’s possible an AHF designed to handle at least 30 amps could be installed to mitigate harmonics on the secondary of the transformer feeding this machine.
      • If all six machines are fed by one large distribution transformer with no other isolation transformers between, then an active filter large enough to handle the entire harmonic amperage ((20 x 5) + 30 = 130 amps) must be installed.

  • Can variable frequency drives be powered from an open delta system?

      There are several issues that occur when a Variable Frequency Drive (VFD) is powered from an open delta system:

      • Uneven voltages in an open delta circuit can cause the diode bridge to unevenly draw current which causes additional heating.
      • The current harmonic distortion caused by the diode bridge will also not be balanced line to line which will cause even more additional heating.
      • Some utilities may require a harmonic study to be performed anytime a large VFD load is to be supplied by an open delta system.

      Overall, an open delta system can result in shorted diodes or DC bus capacitor failures on a VFD. Using DC Link Chokes and/or Line Reactors will mitigate some of this additional distortion. The VFD may need to be de-rated for open-delta configurations.

  • What is Dielectric Material in a transformer?
  • What are the Advantages and Disadvantages to Using a Fan-Cooled Transformer?

      Advantages:

      • Smaller size; fans may add some height but may reduce width and depth
      • Lower costs for larger units (generally above 1000kVA) to add fans instead of conductor and core
      • Potentially better low-load efficiencies

       

      Disadvantages:

      • Increased complexity and maintenance
      • Increased cost as fan packages may cost more than just adding material in smaller units
      • Additional energy losses and noise when fan motors are operated in higher loads

  • What salt spray rating test have Hammond’s painted enclosures passed?
  • Can transformers be operated above a 1000m/3300′ altitude?

      There are two main considerations for operating transformers at altitudes above 1000m/3300′. Current standards state designs must be valid to these heights. Above this height, the density of air no longer works as effectively to remove heat. As a result the functional kVA of the transformer must be reduced at higher altitudes, typically about .3% for every 100m/330′. The second issue is the dielectric constant of air is reduced at higher altitudes. Dry type transformers use air gaps as an important component of the electrical insulation properties. At higher altitudes, this lower insulation values, typically in medium voltage BIL levels. Ideally, if transformers will be installed above 1000m, inform the manufacturer and the design can be adjusted to meet all requirements at the higher altitudes.

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  • What does 50/60 Hertz mean?

      Transformers that are designed to specifically run at 60 Hz can’t be run at 50 Hz or in some cases only with significant derating. Magnetic flux is proportional to frequency so a 50 Hz transformer has a core 20% larger to handle 20% more magnetic flux than a 60 Hz unit. A 50 Hz transformer will simply run cooler at 60 Hz given the proper voltage is applied. Transformers cannot change frequency, the primary frequency equals the secondary frequency.

  • What is U.L. 1562?

      U.L. 1562 covers medium voltage dry-type transformers:

      1.1 These requirements cover single-phase or three-phase, dry-type, distribution transformers, including solid cast and resin encapsulated transformers. The transformers are provided with either ventilated or non-ventilated enclosures and are rated for a primary or secondary voltage from 601 to 35000 V.

      1.2 These transformers are intended for installation in accordance with the National Electrical Code, ANSI/NFPA 70.

      1.3 These requirements do not cover the following transformers:

      1. Instrument transformers
      2. Step-voltage and induction voltage regulators
      3. Current regulators
      4. Arc furnace transformers
      5. Rectifier transformers
      6. Specialty transformers (such as rectifier, ignition, gas tube sign transformers, and the like)
      7. Mining transformers
      8. Motor-starting reactors and transformers

      1.4 These requirements do not cover transformers under the exclusive control of electrical utilities utilized for communication, metering, generation, control, transformation, transmission, and distribution of electric energy regardless of whether such transformers are located indoors, in buildings and rooms used exclusively by utilities for such purposes; or outdoors on property owned, leased, established rights on private property or on public rights of way (highways, streets, roads, and the like).

  • What is U.L. 1561?

      UL1561 covers 600 Volt Class Transformers:

      1.1 These requirements cover:

      1. General purpose and power transformers of the air-cooled, dry, ventilated, and non-ventilated types to be used in accordance with the National Electrical Code, ANSI/NFPA 70. Construction types include step up, step down, insulating, and autotransformer type transformers as well as air-cooled and dry-type reactors

      OR

      1. General purpose and power transformers of the exposed core, air-cooled, dry, and compound-filled types rated more than 10 kVA to be used in accordance with the National Electrical Code, ANSI/NFPA 70. Constructions include step up, step down, insulating, and autotransformer type transformers as well as air-cooled, dry, and compound-filled type reactors.

      1.2 These requirements do not cover ballasts for high intensity discharge (HID) lamps (metal halide, mercury vapor, and sodium types) or fluorescent lamps, exposed core transformers, compound-filled transformers, liquid-filled transformers, voltage regulators, general use or special types of transformers covered in requirements for other electrical equipment, autotransformers forming part of industrial control equipment, motor-starting autotransformers, variable voltage autotransformers, transformers having a nominal primary or secondary rating of more than 600 volts, or overvoltage taps rated greater than 660 volts.

      1.3 These requirements do not cover transformers provided with waveshaping or rectifying circuitry. Waveshaping or rectifying circuits may include components such as diodes and transistors. Components such as capacitors, transient voltage surge suppressors, and surge arresters are not considered to be waveshaping or rectifying devices.

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  • How do you properly size a distribution transformer

      Distribution transformers need to take several items into consideration when sizing including:

      • Maximum Load
      • Potential future load growth (typical is 25%)
      • Load Inrush and voltage regulation
      • Harmonics and Power Factor
      • Ambient Temperature
      • Additional Service Factor

      For reference, NEC Article 210, Branch Circuits, and NEC Article 230, Services is used to select panelboards and the size of branch circuits. Typically a transformer must be sized to support the load requirements of the switchgear, panelboards and branch circuits. For drive isolation transformers, it is suggested to take sizing charts provided by manufacturers into consideration due to derating for harmonics. In addition to sizing a transformer, the general types including general purpose, K-Rated, Harmonic Mitigating and Drive Isolation also need to be chosen.

      Distribution transformers are often sized from loads based on NEC Article 220. NEC Article 220.87 does allow transformers to be sized based on peak-load data over a 1-year period. NEC also allows loads to be sized using metered data over 30 days if the additional maximum anticipated heating and/or cooling load is also factored in. This often allows a transformer to be sized lower than the base calculations from NEC Article 220. Peak efficiency for 600V class distribution transformers is typically at 35%. Peak efficiency for medium voltage transformers is typically at 50% load.

      Additional capacity for future loads can be obtained by A) specifying a lower temperature rise (15%-30% for dry type) or B) utilizing fans (25%-50% for dry type).

  • Are there voltage drop concerns when using a load reactor or dV/dT filter for long lead lengths?
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  • What are NEMA Premium Efficiency Transformers?

      NEMA Premium provides 30% fewer losses than the 2006 DOE 10 CFR Part 431 (commonly called TP1) or Canadian C802.2. This covers low voltage distribution transformers and is measured at 35% load.

      NEMA Premium is largely obsolete as a term and has been replaced by similar efficiencies in the U.S.A’s DOE 2016 and Canada’s NRCan 2019 energy efficieny regulations. NEMA no longer promotes the NEMA Premium specification or specifications higher than the current DOE 2016 and NRCan 2019 levels.

  • What problems can occur if I undersize the short circuit protection on a transformer?

      Nuisance tripping is a concern when short circuit protection is undersized from the National Electric Code recommendations in NEC 450.3.  All transformers experience an inrush current during any energization. The inrush current results from the transformer establishing the initial electromagnetic field and is not linked to load. If short circuit protection is undersized, there is a chance for nuisance tripping of fuses and circuit breakers anytime the transformer is energized.

  • Do any performance issues arise during high ambient temperatures?

      Temperatures which exceed the rated ambient temperatures for which the insulation system is designed can cause insulation damage and premature failure. This can often occur in hotter
      environments or in rooms which have inadequate ventilation. Care should be taken in installing stacked transformers because the top transformer may use air that has been heated by the lower unit. Damage from high ambient temperatures often does not cause an immediate failure but can cause damage that results in a failure weeks, months or years later.

      High ambient temperatures can be mitigated several ways:

      • Order a transformer designed with a lower temperature rise.
      • Use fan cooling, this is typically an economical solution when a unit exceeds 500-1500kVA.
      • Place the transformer in a temperature controlled location.
      • Properly ventilate the location that the transformer is located in.

      Never try to use cooling fans directly on a transformer or blow across a transformer’s windings.

      Manufacturers use special fans, specific locations, and cooling patterns to cool transformers. Improper placement of airflow could cause disruption of the convection airflow and cause the transformer to overheat.

  • Do any performance issues arise during low ambient temperatures?

      Generally low ambient temperatures do not affect an energized transformer. No-load losses on an energized transformer typically generate enough heat to operate effectively in temperatures to -20°C or lower.

      The main issue with lower temperatures is when the unit is not energized. Extremely low temperatures or if the transformer heats up too quickly may cause welds and insulation to become brittle and crack, especially if the transformer experiences any mechanical stresses.

      More importantly, low temperatures can cause moisture (dew, frost) to form on the unit. This can be absorbed into the insulation system and not be apparent.

      If ambient goes below -30°C, special designs and cold start procedures may be necessary. Care should be taken to store transformers in dry areas with temperature control. Installation manuals typically suggest that transformers be tested (meggered), brought above 0°C and/or go through a dry-out process if moisture is suspected to be present.

      Damage and injury can result from energizing a transformer which has had its insulation system compromised by moisture.

  • Can a damaged coil be repaired, refurbished or replaced?

      Low and medium voltage coils which have been damaged can be repaired, refurbished or replaced. Repairing involves fixing the issue without removing the coil from the core. This may be an option for transformers which have sustained much physical damage or if an issue such as lowering insulation levels is diagnosed before actual failure. This may also be possible for transformers which are dirty or have been submerged. In some cases the the coil can be removed and refurbished. This would typically be done for larger, often medium voltage transformers which have sustained damage to the outer, primary winding. The last option is to replace the coil entirely which is often done if the coil is severely damage, the inner winding is damaged or the transformer can’t be sufficiently cleaned.

      While coils can be repaired, refurbished and replaced, this must be compared to the cost of providing a new unit. Repairs must factor in additional transportation and testing costs, higher disassembly and assembly costs, core damage and replacement and the benefits of using a new transformer, often with modern higher efficiencies. Repair is often only practical for large custom transformers.

  • Is ice snow or frost conductive

      Yes, ice, snow and frost are conductive and should be considered in the same terms as the liquid form of water. If ice, snow or frost come into contact with energized parts of a transformer, a fault and damage can occur. If a fault doesn’t occur initially, the heat from an energized transformer will cause ice, snow and frost to melt which can further increase the chances of a damaging fault occurring.