Questions concerning medium-voltage transformers : LUSENET : Commercial and Industrial Transformers : One Thread

The CEE Transformers Working Group is currently considering an initiative to promote high-efficiency C&I medium-voltage transformers. In the process of determining whether to address this area, CEE needs to address the concerns delineated below. If you are able to answer any of these questions and substantiate your claims, please share your thoughts with us.

1. Are there two separate markets for medium voltage dry and medium voltage liquid? (need industry data other than from ORNL). If they are separate markets, why?

2. What codes influence medium-voltage dry-type transformer purchases, and what other factors are driving the market?

3. What is the opportunity in the dry-type market?

4. Should the EPA ENERGY STAR MOU be revisited if C&I users are exhibiting an increasing trend toward purchases of LI transformers?

5. What is the range in efficiencies available from manufacturers for dry-type (best/worse case)? (need a confirmation outside of ORNL data)

6. What is the breakdown of medium-voltage dry-type (and less importantly liquid-immersed) purchases by utility and non-utility consumers?

7. How highly are medium-voltage dry-type products loaded?

8. Does the typical load vary for dry vs. liquid?

9. Are dry-type medium-voltage commodity or custom products?

10. What is the typical purchasing behavior of C&I customers like?

11. To what extent is lifecycle costing used for larger transformer purchases?

12. What is the difference between dry-type and liquid-immersed medium voltage transformer efficiency? Does this difference exist and how big is it?

13. The savings potential estimated by ORNL (97 Supplement, Table 4.8, p.4-14) shows relatively small relative savings from non-utility liquid medium voltage (215 million kWh) vs Dry medium voltage (1041 million kWh); is this due to higher sales volume for dry, or efficiency gap?

14. How many units and total kVa of medium voltage, liquid are sold to non-utility purchasers? What are typical/representative non-utility sizes?

15. Could we get data like ORNL 97 Supplement Table 5-4 for non-utility medium voltage liquid and dry?

16. Is there any data available on typical/average efficiency levels for non-utility medium voltage liquid?

17. What are typical efficiencies (core and winding losses) for dry type and what is the range available from manufacturers (best case/worst case)? We need this less, since ORNL collected this (see Table 5.8) although confirmation and current data would be helpful. This table provides manufacturer survey data on load losses and load losses for non evaluated transformers (e.g., the worst efficiency case) and transformers designed to meet TP-1. Hence with accurate loadings -- which to date we don't have, we could calculate efficiencies.

18. Who are the top 5 manufacturers of non-utility medium voltage liquid, or is this just designer/customer preference?

19. Does the development of new technologies hitting the market, such as amorphous core transformers offer an opportunity for Energy Star to target efficiencies higher than TP-1?

20. What is the opportunity in the DT market -- starting with real measured loadings (in comparison with the F0% used in NEMA TP1. Here we REALLY need the data.

21. On savings potential, both sales volume and efficiency gap contribute to the gap in savings potential between DT and LI MV transformers sold to non utility customers. All of the data to support this statement is in the ORNL report.

-- Mahri Lowinger (, July 21, 2000

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