Sampling Oil-Filled Transformers EUS 210

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

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.

Valve Types Ball Valve Gate Valve Globe Valve

Drain Valves and Locations

Drain Valves and Locations

Drain Valves and Locations

Drain Valves and Locations Cast Iron Brass Bronze Stainless Steel

Drain Valves

Final Assembly

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

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

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

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

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

Water Ingress into Sample Containers

Bottle Types -Glass, Plastic, Metal

Glass Syringes and Metals bulbs

Examples of Inappropriate Containers

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

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

Materials Needed

Materials Needed

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

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.

Watch out for Unforeseen Dangers!!!

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

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

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

Sample Identification

Sample Identification

Collecting the Sample https://www.youtube.com/watch?v=efmUxF_dcro https://www.youtube.com/watch?v=9XqaWiko1ks https://www.youtube.com/watch?v=aFCdMLOG9Cg https://www.youtube.com/watch?v=JlpRPEkFtmo