NEMA TP-1 Transformers

[peebee]

I'm trying to determine if we should stick to general purpose transformers, consider NEMA TP-1/EnergyStar transformers, or standardize on NEMA TP-1 for all projects. Any insights, thoughts, observations, links, etc., would be appreciated. I'm primarily interested in dry-type transformers, but information on liquid-filled transformers would also be helpful.

1. I've heard that some states are requiring that TP-1 transformers be installed for all new installations -- does anyone have any additional information on this? In particular, is anyone aware of a website which tracks this and updates the list of such states?

2. Is anyone aware of any other legal requirements for TP-1 transformers? Or any published documents which recommend their installation (LEED and ASHRAE 90.1 come to mind, but so far as I know, neither of them addresses transformer type).

3. Is anyone aware of any trends for companies or industries standardizing on TP-1?

4. Are there any consulting engineers out there specifying TP-1? Do you recommend TP-1 to your clients? Do they require TP-1? Do you specify it for all projects?

5. Has anyone seen any good technical articles on TP-1?

I'll throw in a link of my own to help get things started, this appears to be a relatively good comparison of TP-1 to GP and Premium designs:

http://energy.copper.org/energy-star.html

For anyone not familiar with NEMA TP-1, they are a relatively new design which optimizes the transformer efficiency for a 35% loading (50% loading for medium voltage transformers). This was based on various studies which indicate that most dry-type GP transformers are only loaded to 35%. And at that loading, they should have lower life-cycle costs despite higher initial costs (one vendor has told me to expect a 30-35% cost premium for TP-1). However, GP transformers could have a lower life-cycle cost when they are lightly loaded or where they are shut off at night. And Premium Efficiency transformers could have lower life cycle costs where the transformers are heavily loaded.

 

[busbar]

Long-shot possibility:

http://www.energy.ca.gov/2005_standards/documents/public_comments/

measure_information/2001-11-05_Gates-03.doc

 

[peebee]

Thanks, bus.

Here's some more links I've found, for anyone else who's interested. I'd still appreciate any other information.

Energy.Copper.Org TP-1 vs GP Comparison

http://energy.copper.org/energy-star.html

This is an excellent comparison of GP, NEMA TP-1 Aluminum, NEMA TP-1 Copper, and NEMA TP-1 Premium Efficiency transformers, and includes a great table which summarizes the installation costs, energy costs, and payback periods for each transformer type at various transformer loadings and at $0.06 per kWh. Beware -- Energy.Copper.Org is perhaps somewhat biased towards copper windings. . . .

TP-1 TX's -- by State (CEE):

http://www.ceeformt.org/resrc/updates/02-03trnsfm/02-03trnsfm.html#codes

This site lists states that require TP-1, are considering adopting such a requirement, or are offering incentives

High-Efficiency Commercial and Industrial Transformers Initiative (CEE):

http://www.ceeformt.org/resrc/facts/trnsfm-fx.php3

A nice overview of TP-1 Transformers.

Square D TP-1 Case Study

http://www.cee1.org/ind/trnsfm/sq-d.pdf

This is an analysis of an existing Square-D office building's transformer loads, and a discussion of the suitability of TP-1 and K-rated transformers given their existing loads. Interesting reading.

NEMA TP 1-2002

http://www.nema.org/DocUploads/5AFB1B24-991A-4982-AD6040030152FBE1/TP1.pdf

This is the NEMA TP-1 document itself. Rather dry, and probably not very helpful to you, but here's the link just in case you're interested.

 

[peebee]

I'm a little surprised by the underwhelming response.

Is anyone using these things? Has anyone heard of them?

 

[jbartos]

Suggestion: There is also some room left in an optional selection of the transformer magnetic steel. The better steel (more expensive) means the higher transformer efficiency. Some manufacturers of custom transformers leave the steel selection optional.

 

[RAMConsult]

The engineering portion seems obvious, lower losses translates into lower TCO (total cost of ownership), now you have to put on your sales hat and convince the building owner to pay more up front. The easiest way to do this involves looking beyond the transformer and into the building system.

Some of the less obvious savings:

1.)Reduced air conditioning load (if xfrmrs are in conditioned space) , which could result in smaller tonnage (double savings- less heat to be removed translates into less energy to remove it);
2.)Reduced load may result in smaller feeder and/or service entrance equipment size;
3.)Reduced demand charges.

Instead of the savings, try showing the hidden costs of the 'lowest initial cost' approach.

 

[RonShap]

The firm I work with does not generally specify the TP-1 standard. I also understand that some jurisdictions require or will require this listing. The listing appears to have specific strategies related to efficiency. Manufacturers are trying to tweak their transformer designs to comply specifically to the criteria at the load required and having no regard for other loads or applications.
I understand that GE is trying to release a small dry type transformer the has this listing, but has reliability issues, as it uses non-redundant fans to accomplish the efficiency at that specific load per the standard. It doesn't sound like it is an all around transformer, unless you know it will be at that load and don't mind the fan noise and associated maintenance.

 

[stevenal]

We evaluate losses in the bid process, leaving it to the manufacturers to determine whether a low loss transformer is competitive. Load and no load losses are converted to dollar figures that are added to purchase cost before choosing the lowest bid.