From: Robert Berman [mailto:bermaneconomics@gmail.com]

Sent: Sunday, October 16, 2011 11:13 AM

To: Hirsch, Bruce R

Cc: 'Richard Parker'; Alex Hofmann; Andrew Delaski; Aris Marantan; Art Rosenfeld; Bob Saint; Brian

Coffey; Bruce Smith; Caitlin Johnso n; Carlos Gaytan; Caskey, John; Charlie Drexler; Charlie Stevens;

Chris Bolduc; Clark Silcox; Creevy, Jim; Dan Cohen; Daniel Young; Eric Peterson; Freeman, Jeremiah;

Gary Fernstrom; Greg Coulter; Greg Rosenquist; James Lass; Jennifer Tiedeman; Jerry Corkran; Jerry

Hodge; Jerry Schoen; Joanna Mauer; John Cymbalsk y; John Rossetti; Katie Coughlin; Ken Winder;

Mahesh P. Sampat; Matt Miller; Matthew Nardotti; Me g Waltner; Meyers, Aaron; Michael Hyland; Michael

Rivest; Millure, Dave; Phil Harter; Phil Hopkinson; Po linski, Raymond; Puesh Kumar; Rick Anderson; Rob

Greeson; Robert Berman; Robert van Buskirk; Robin Roy; Ryan, Paul; Scott Beck; Simmons, Chuck; Steve

Nadel; Steve Rosenstock; Tim Ballo; Tom Eckman; Wes Patterson; Zhimei Luo

Subject: Re: Amorphous Core Experience at BGE

Importance: High



### Very strange results. You're talking about two cl osely related distributions . If the expected life

for 93% is 30 years, and the average age of the 7% was 11 years, the only statistical inference

that you could reasonably make is that the 7% appeared to have b een drawn from a very different

population -- a different distribution -- or, perhaps even mu ltiple distributions and populations.

Clearly the expected value and variance of the di stributions are significa ntly different. Rather

than an apples-to-apples comparison, the set of numbers provided is anything BUT apples-toapples. The more information you can get on the failed units, the better. Indeed, your experience

with the amorphous units generally is significantly better than the 88%/7 8%/47% survival rates

for DOE compliant transformers generally afte r 10/20/30 years re spectively. As a start, if you

don't have any information about the failures, I woul d look at a plot of the ages at failure for the

7%. Based on the numbers you provide, I would e xpect to see a "clump" (technical statistical

term) in the data, probably occurr ing in the late '80s or early '90s (to make your distributions

balance out). The statistician in me suspects a single bad batch or other anomalous event. A

either would both explain the numer ical results you obtained as we ll as reconcile the apparently

conflicting results and confirming th at at lest a portion of the 7% came from a very different

population.

On the upside, it's worth noting that its probabl y a good thing that BG&E didn't get any of the

HVOT transformers that Mr. Hopkinson reports he unsuccessfully tried to build. Your

experience, generally, seems to be consistent with the high quality amorphous product lines

marketed by the 4 manufacturers represented on this committee, and totaling more than 2.3

million units internationally. Although I confess that I have difficulty seeing any relevance to

this committee's task of how much the effici ency standard should be increased to Mr.

Hopkinson's inability to build tr ansformers or his obvious personal distaste for the highly

efficient amorphous material successfully used for more than 30 years by most or all major

manufacturers.



### Regards,

Robert A. Berman, Principal

Berman Economics

www.BermanEconomics.com

### 1915 Grand Court

Vienna, VA 22182

703

‐ 281

‐ 0490

703

‐ 655

‐ 8398 (cell)

BermanEconomics@gmail.com

On Oct 14, 2011, at 12:16 PM, Hirsch, Bruce R wrote:

This is just a single Company’s experience with amorphous core transformers. Please note that based on

this data we have NOT ruled out using amorphous steel in our transformers, however, the numbers are

troubling.

BGE owns 2,770 transformers with amorphous steel cores. Most are three phase units purchased in the

mid to late 80’s.

Of that number, 201 have failed in service. The cause of failure is not known but to be considered a

failure the probability is that either the core or coil failed. This represents an 7% failure rate.

The average age of the failed amorphous core transformers is 10.97 years.

The average age of failed transformers for BGE’s entire fleet is 29.4 years.

BGE has over 216,000 transformers in the fleet, thus the quantity of amorphous core transformers

represents 1.4% of the total.

While we could debate the cause of failure for any particular class or design of transformer, the average

age to failure date is a good apples to apples comparison of the performance of the transformers since

the exact same criteria was used across the board.

Hope this information, along with other user responses is helpful in the decision making process.

Bruce



### >>> This e

‐ mail and any attachments are confidential, may contain legal,

professional or other privileged information, and are intended solely for the

addressee. If you are not the intended recipient, do not use the information

in this e

‐ mail in any way, delete this e

‐ mail and notify the sender. CEG

‐ IP2