Peak Measure

2014 Transformer

Seminar

DGA Case Studies-

Trusting your Results

Incident at Mirant Mid-Atlantic Morgantown Plant, MD

Transformer Type: 650 MVA GSU

Table 2: H2 generating rates from May 30th to Sept. 26th, 2002

Sudden increase in Hydrogen generating rate

Table 5: DGA results – Sept. 30th 2002

The Cause: Burned high voltage lead

Mirant GSU – Update as February 19th, 2003

Data from unit after repair …

Event Log

Alarms should not be ignored

Incident in India--This transformer failed….

Entergy Louisiana USA

Nine Mile U4 XFMR location

• Calisto 9 installed in October 2011 on brand new GSU 500 MVA.

• All faults gases started increasing on October 14th significantly.

• First lab data did not match Calisto 9.

• Gases continued to increase.

• A second lab was used and analysis data matched C9 results.

• The GSU was shutdown , OEM was called in , emptied the oil and made

some repairs.

• GSU was restarted and gases continued to rise.

• Unit was shutdown and send back to OEM facility oversea for complete

review and repair.

7”

The decision to use an installed multi-gas Dissolved Gas Analysis (DGA) instrument (Calisto 9) was primarily made by our technical group. I did not have much experience with transformers gassing or DGA using either manual sampling or by an installed online type instrument prior to this installation. However, I did find the speed, consistency and the ease of obtaining the DGA results for the XFMR especially during start up when we unexpectedly experienced gassing problems. The installed multi-gas DGA instrument alerted us very early in the process and I think it did keep a total failure of the XFMR from happening. The installed multi-gas DGA instrument doing the oil analysis every 3 hours or every hour made it extremely easy to see the rate at which the XFMR was producing gas. We utilized manual samples to cross check and verify the installed multi-gas DGA instrument and the lab results supported what the installed DGA instrument was telling us but while good, the lab results were not as constant as the results from the installed multi-gas DGA instrument. When it comes to large GSU XFMRS or other large critical XFMRS I think having an installed multi-gas DGA instrument is well worth the investment.`

Regards John C. Lawrence, P.E. Sr. Electrical Engineer Entergy Services Nine Mile Point 1617 River Road Westwego, LA 70094 jlawre5@entergy.com (w) 504-436-5971 (c) 504-884-0460

Testimonial

TRENDING RESULT (ppm) 17/8/2012

TRENDING RESULT (ppm) After Oil Purifier

ข้อมูลจาก วนัที ่12/08/2012 ถึงวนัที่ 17/08/2012 หม้อแปลง EAF หลงัจากกรองน า้มนั หม้อแปลง EAF หลงัจากกรองน า้มนั H2(ppm) อตัราการเพิ่มข้ึน 3.1 ppm/day CO(ppm) อตัราการเพิ่มข้ึน 2.0 ppm/day CO2(ppm) อตัราการเพิ่มข้ึน 19.0 ppm/day CH4(ppm) อตัราการเพิ่มข้ึน 7.4 ppm/day C2H2(ppm) อตัราการเพิ่มข้ึน 0.0 ppm/day C2H4(ppm) อตัราการเพิ่มข้ึน 8.2 ppm/day C2H6(ppm) อตัราการเพิ่มข้ึน 2.2 ppm/day O2(ppm) อตัราการเพิ่มข้ึน 240 ppm/day N2(ppm) อตัราการเพิ่มข้ึน 400 ppm/day

23/08/12 Change the Transformer and Repair

23/08/12 Change the Transformer and Repair

Wrap-Up