The Department of Energy (DOE) published a Notice of Request for Information (RFI) in the September 22, 2017 issue of the Federal Register (82 FR 44347) on the test procedure for distribution transformers. This article intended to break down what exactly is being requested by the DOE, the steps that have come before and will come after this, and what it might mean for you.

What is this notice?

I’ve covered what an RFI entails my article on the DOE’s RFI for its net metering analysis, as well as the overall federal rulemaking process in the Policy Rulemaking Process for Dummies article—so click on those links to get the background information on those aspects of this process. However I have not had a chance to detail the DOE’s dealing with test procedures.







As detailed in the ‘Authority and Background’ section of the RFI, the Energy Policy and Conservation Act of 1975 (EPCA) authorizes DOE to regulate the energy efficiency of a wide array of covered consumer products and industrial equipment. Among that list of equipment is distribution transformers. As such, DOE first established regulatory standards for distribution transformers in 2007, and most recently completed full rulemaking process to update to the energy conservation standards for distribution transformers in 2013, which took effect in 2016. These standards set minimum energy efficiency standards for the equipment based on the type of distribution transformer, the applicable kVA rating, and BIL rating, and those final standards can be found here.

The authority of EPCA calls on DOE to not just set the minimum energy efficiency standards for distribution transformers (and other equipment), though. DOE is also responsible for setting the testing requirements, which manufacturers must use as a basis to 1) certify to DOE that their equipment complies with standards, and 2) make representations of the efficiency of their equipment to the public (e.g., through in manufacturer catalogs). In other words, the official DOE test procedure dictates the testing setup and methods in which the efficiency of the equipment is measured.

DOE currently has test procedures for distribution transformers, which can be found here. These test procedures were published in 2006 when the first efficiency standards for the equipment were published as well. As noted in this RFI, “EPCA requires that, at least once every 7 years, DOE evaluate test procedures for each type of covered equipment, including distribution transformers, to determine whether amended test procedures would more accurately or fully comply with the requirements for test procedures to not be unduly burdensome to conduct and be reasonably designed to produce test results that reflect energy efficiency, energy use, and estimated operating costs during a representative average use cycle.” In fact, during the 2013 update to the energy conservation standards for distribution transformers, DOE did just that and determined that the current test procedures were satisfactory and did not require an amendment. However during that rulemaking process, certain stakeholders took advantage of the opportunity to make a public comment and noted that the requirements for ‘percent of nameplate-rated load’, or PUL, of the test procedure might not be appropriate and should be addressed in a future test procedure rulemaking. This RFI published by DOE is the beginning of that promised future test procedure rulemaking on distribution transformers, set to give consideration to the test PUL requirements.

Background of Distribution Transformers

As detailed in the RFI, a transformer is “a device consisting of 2 or more coils of insulated wire that transfers alternating current by electromagnetic induction from 1 coil to another to change the original voltage or current value.” 10 CFR 431.192 Distribution transformers, according to the DOE definition, are specifically identified based on their input and output voltage and other electrical characteristics. Put simply, distribution transformers are the pieces of equipment that take the high-voltage power from transmission lines and step that power down to its safe, final voltage before it is sent to the customers (in their homes, commercial buildings, etc.). These distribution transformers can be found either on a utility pole or in a locked box on the ground. Depending on the area, a single distribution transformer might serve one customer (in a remote rural area) or it might serve many customers (in a dense urban area). Further, a single large industrial facility might require multiple distribution transformers of its own.

The full current test procedure for distribution transformers can be found here, which specifies the test system accuracy required; the methods for measuring resistance, losses, and efficiency value of the transformer; and the test equipment calibration and certification.

What is being requested

This RFI is the beginning of a full rulemaking cycle on the test procedures for distributed transformers, so this is the opportunity for stakeholders to make an early and strong impact on the direction of the rulemaking.

The main issue that was brought up during the 2013 energy conservation standards rulemaking with regard to the test procedure was the appropriateness of the PUL specification. The discussion of this issue centered on the idea that the PUL on which the transformers were tested, and thus the PUL on which the resultant declared efficiencies were based, are potentially not representative of the PUL at which the transformers would operate during actual use. If this is the case, then customers seeking out the transformer that would use the least energy might be misled, and transformers that actually save more energy than others in use might be found non-compliant with regulations. To address this issue, DOE is requesting comment on the following:

Issue 1: Any data or information on the PUL used during the first year of service for distributed transformers;

Issue 2: Typical PUL values used in the population of distributed transformers;

Issue 3: Whether data provided by manufacturers represents first year of service or full lifetime;

Issue 4: Whether transformer loads increase over time; and

Issue 5: How much the efficiency of a transformer effects the purchasing decision of customers.

DOE is also going to investigate the issue of temperature correction and if the current practice of calculating losses by assuming the temperature inside the transformer is equal to an outside ‘reference’ temperature. The concern is that the temperature inside the transformer is surely higher than an outside temperature, meaning the energy losses in practice would be higher than what is being calculated. To address this, DOE is requesting comment on the following:

Issue 6: Any data or information about whether calculating losses at ambient temperature or internal temperature is more representative of real transformer performance; and

Issue 7: Whether temperature varies with PUL.

The current test procedure specifies efficiency by a single tested PUL. DOE has engaged in some discussion on whether this is appropriate, if a different reference PUL should be used, or if transformers should be tested at multiple PULs. To this end, DOE is requesting comment on:

Issue 8: Any data or information on the continued use of a single PUL test requirement compared with the alternatives;

Issue 9: How accurate would testing at multiple PULs be to the distribution of real-use transformer operations and how much would that increase testing costs;

Issue 10: How many PULs would be appropriate at which to test in a scenario of testing multiple PULs; and

Issue 11: Whether there are alternative metrics that should be considered to determine transformer efficiency.

Lastly, DOE also seeks comment on the sampling process and calculation methods used in the test procedure. The specific types of comments DOE seeks are the following:

Issue 12: Whether the sampling requirements of units to be tested should be adjusted;

Issue 13: Whether the efficiencies advertised by manufacturers typically represent the minimum efficiency standard, the maximum represented efficiency they are allowed to use, or some other metric;

Issue 14: Comment on DOE’s requirements related to alternative methods for determining energy efficiency (AEDMs); and

Issue 15: Whether the AEDM provisions are useful and if manufacturers use them.

Again this RFI is just the beginning of the rulemaking process for the distributed transformer test procedure, but it also represents the best time to get involved if these test procedures affect you. The above issues are just the ones that DOE specifically is looking to hear about, but stakeholders are more than welcome to address any other topics they find important. As mentioned in the Policy Rulemaking Process for Dummies article, comment periods such as this one represent the best opportunities to directly impact potential regulations that could have real impacts on you or your business.

Note: I have in the works a post on how to submit the most effective public comments, so if there appears to be interest on this post regarding the net metering RFI then I’ll make sure to move up publication of that subsequent post to be helpful for commenting on this Notice in advance of the comment submission deadline. Update: See here for my post on how to make the most effective public comment on a public rulemaking.

Summary of RFI details

DOE published RFI asking for comments on development of the technical and economic analyses regarding whether the existing test procedures for distributed transformers should be amended (82 FR 44347).

Some key specific topics DOE is interested in receiving comments on include: Ways to streamline and simplify testing requirements; Measures DOE could take to lower the cost of testing requirements; The relation between PUL being tested and PUL actually used in the field for distribution transformers; Whether current temperature correction in the test procedure is flawed; How testing based on a single PUL affects the final posted efficiency of equipment; and The appropriateness of the sampling and calculation methods currently used.

Comments are to be submitted by October 23, 2017.

Further information is available at the Notice’s online docket, and questions can be directed to Jeremy Dommu at the DOE Office of Energy Policy and Systems Analysis or Mary Green at the DOE Office of the General Counsel.

As always, feel free to contact me through the Contact page or commenting below if you have any questions you think I could answer as well.







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To see further assessment of energy conservation standards, see this post on the request for information for net metering, this assessment of the changes brought to energy conservation standards from the Trump administration, and this overview of the federal rulemaking process.

About the author: Matt Chester is an energy analyst in Washington DC, studied engineering and science & technology policy at the University of Virginia, and operates this blog and website to share news, insights, and advice in the fields of energy policy, energy technology, and more. For more quick hits in addition to posts on this blog, follow him on Twitter @ChesterEnergy.