ACTION PLAN FOR UPTEGRAFF TRANSFORMER AT
ARECIBO OBSERVATORY - ARECIBO, PUERTO RICO
Customer: Arecibo Observatory, End of Road 625, Arecibo, Puerto Rico 00612
Attn: Dr. Michael Nolan
Office: 787.878.2612 ext. 212 Fax: 787.878.1861 e-mail:
Transformer Manufactured on Uptegraff Order No. G-1645, Spec. No. 9480, Ser. No. 24B94
1. Safety is job 1. Overall transformer is rated a condition 4 due to high levels of hydrogen (severe partial discharge), acetylene (severe arcing activity), ethylene (severely over heated oil) and carbon monoxide (severely over heated cellulose insulation).
2. Don’t energize the transformer (due to high levels of combustible gas in DGA).
3. High level of acetylene indicates arcing above 700 degrees Celsius.
4. Filtering the oil may not help the visibility problem (open for discussion).
5. There could be a lot of metal floating in the oil. If the rectifier side is the problem and the transformer side is good, the transformer could still fail if repairs are made in the field.
6. The moisture content test (ASTM D-1533b) result is 69 ppm. New transformers are 5 ppm or less. Transformers in service shouldn’t exceed 15 to 20 ppm. There could be free standing water lying on the bottom of the tank. Moisture may be the root cause of failure.
7. If filtering the oil doesn’t increase the visibility, you could pump the oil down to the bottom of the frame on the core and coil assembly. The coils must remain under oil.
8. With the oil pumped down, you can inspect the rectifier assembly for damage through the manhole.
9. If you see damage on the rectifier, you can decide if you want to untank in the field.
10. If you untank in the field, you’ll need a tent over the transformer to protect it from the weather while it’s open.
11. There is enough oil at the lab to run additional tests. We should run Fault Metals (D-3635-ICP) test for all metals or just copper and aluminum.
12. The transformer should come back to the factory for testing and repairs.