1. Sampling Oil-Filled Transformers
EUS 210

2. Types of Dielectric Mineral Oil Polychlorinated biphenyls (PCBs)
Silicone-based or Fluorinated Hydrocarbons
Natural and Synthetic Esters
Air

3. Why Do We Sample the oil In-Service Electric Transformer:
Provides a method to determine the condition of the solid and liquid insulation without opening the transformer.
The results of tests of the oil sampled can be used as a diagnostic tool to determine the operating condition of the transformer.

4. Valve Types
Ball Valve
Gate Valve
Globe Valve

5. Drain Valves and Locations

6. Drain Valves and Locations

7. Drain Valves and Locations

8. Drain Valves and Locations
Cast Iron
Brass
Bronze
Stainless Steel

9. Drain Valves

10. Final Assembly

11. Clean Sampling is Key Results Before and After Flushing
Copper
Lead
Iron
Zinc 63 10 33 6 1 4 44 19 14

12. Cost of Samples Item Cost ($) Original Sampling Labor 275
Materials to take sample 15
Packaging & Shipping 8
Analysis 70
Engineering Evaluation 35
Total
403

13. Examples of Volumes Required
Test
Volume
DGA
40 mL
Water Content
10 mL
Screen
1000 mL (1L)
Inhibitor Content
1 mL
Furanic Compounds
20 mL
PCB
Dielectric
80 to 500 mL
Power Factor
250 mL

14. Sample Container Purpose
Large enough for the tests required
Does not contaminate the sample
Seals the sample from external contamination
Shields the sample from sunlight
Prevents the loss or gain of properties or materials being tested

15. Recommended Containers
General Sampling: Glass bottles (amber, clear) aluminum, steel or tin cans, HD polyethylene bottles
DGA Sampling: Ground Glass Syringes or SS Cylinders
Water Content: Ground glass syringes, glass or metal bottles, no plastic containers
Note: glass containers help visual inspection

16. Water Ingress into Sample Containers

17. Bottle Types -Glass, Plastic, Metal

18. Glass Syringes and Metals bulbs

19. Examples of Inappropriate Containers

20. Concerns with Tubing Tigon Tubing: One time use only
SS Tubing can be using more than once if flushed from previous test

21. Sampling Technique Materials used to aid in retrieval of a sample
Safety precautions to adhere to
Environmental concerns
Identification of the sample and apparatus information
Final checks prior to sampling
Taking the sample (cleaning and preparation of valves)
Cleanup after sample has been retrieved

22. Materials Needed

23. Materials Needed

24. Safety precoutions
Positive pressure on the electrical apparatus (even if it is a free breathing apparatus)
Take into consideration the remaining volume in a low oil volume apparatus (this may require de-energizing the equipment and adding oil when finished)
De-energize instrument transformers and network transformer switches before sampling
Secure electrical dangers
Make sure you adhere to Occupational Safety and Health Administration (OSHA) requirements

25. Environmental Concerns
Oil or fluid spillage will occur
Abide by company directive
Obey EPA, state and local regulations concerning cleanup, storage and disposal of hazardous materials.

26. Watch out for Unforeseen Dangers!!!

27. Taking the Sample
Flush at least 2 to 4 liters of oil through valve (about .5 to 1 gallon)
If taking syringe and bottle samples, take the syringe last
Rinse bottles with about 1/3 volume unless particle free bottle
Fill without causing aeration

28. Taking the Sample Bottles –Fill to shoulder and seal
Cans, Steel Cylinders, Plastic bottles
–Fill to overflowing and seal
Syringes
–Flush 2 to 3 times
–Remove gas bubbles immediately
–Don’t remove after sample has cooled down

29. After the Sample is Taken
Close valve (sampling cock)
Record top oil temperature
Clean valve
Re-install drain plug
Clean area and remove all debris
Make sure all samples are labeled

30. Sample Identification

31. Sample Identification

32. Collecting the Sample https://www.youtube.com/watch?v=efmUxF_dcro