ELTEK Labs conducts low, medium and high voltage EIS transformer testing.
The test methods of the evaluation of Electrical Insulation Systems (EIS) are developed mainly by two organizations: IEC and the IEEE. The following table shows the IEEE test methods for the evaluation of EIS for Rotating Machinery and Transformers which are conducted at ELTEK Labs.
The titles are copied directly from the IEEE website. Additional information about these test methods including the scope of each standard or copies of any IEEE Standards can be obtained from their website.
For any questions about the testing/evaluation of your candidate EIS to any of these specific IEEE Standards by ELTEK Labs, please contact us directly. All of these tests are listed on our IAS Certificate.
- Test Voltage up to 150kVAC
- Temperature exposure (thermal aging) at temperatures up to and including 350C.
- Impulse testing up to 48kV; please refer to the Impulse Test page for more details.
Watch our video about Medium and High-Voltage EIS Transformer Testing
|IEEE Publication Number
|Recommended Practice for Thermal Evaluation of Unsealed or Sealed Insulation systems for AC Electric Machinery Employing form – wound Pre-Insulated Stator Coils for Machines Rated 15,000 V and Below Procedure A and Procedure B Impulse testing up to 48kV
|IEEE Guide for Test Procedures for Thermal Evaluation of Insulation Systems for Solid Cast and Resin-Encapsulated Power and Distribution Transformers
|Test Procedure for Thermal Evaluation of Insulation Systems for Ventilated Dry-Type Power and Distribution Transformers
|Standard Test Procedure for Evaluation of Systems of Insulation for Dry-Type Specialty and General-Purpose Transformers
|Standard Test Procedure for Thermal Evaluation of Insulation Systems for Liquid-Immersed Distribution and Power Transformers
Oil Filled Transformers (OFT)
The Oil-Filled Transformer (OFT) segment of our industry has special needs related to the evaluation of new materials, new processing, new/replacement/modified/alternative oils being introduced to a transformer system. We have the capability to assist you in your testing needs, whether it be the evaluation of individual materials, or an established Electrical Insulation System (EIS) used in an Oil-Filled Transformer.
Step 1: Evaluation of the Oil
The first step in evaluating any proposed changes to a system is to gain an understanding of the maximum operating temperature any oil can endure without altering the original nature of the oil. It is essential to evaluate the oil after exposure to a range of elevated temperatures.
An established test method is ASTM method D3455 for Oil Compatibility. In method D3455, the oil is aged at a single elevated temperature. This test method assumes the behavior of the oil is already known and the selection of a single temperature is based on the known behavior of the oil. To determine or to confirm the maximum temperature oil, specimens should be aged across a range of temperatures and perform the series of tests to evaluate the oil after heat exposure.
Thermal decomposition or alteration of the oil should occur in a short period of heat exposure. The suggested time for the heat exposure is 10 to 14 days.
Step 2: Evaluation of any material with the Oil = Oil Compatibility
Once the maximum temperature has been established, the decision of the preferred aging temperature for the evaluation of any material with the oil can be performed by again following the procedure of ASTM method D3455. After the agreed upon length of time at the selected temperature the oil has been completed, material(s), can be evaluated for retention of properties.
Step 3: Evaluation of the EIS for use in OFT
3A. The IEC test method
The IEC approach has two test methods; IEC 62332-1 and 62332-2.
IEC 62332-1: Electrical Insulation Systems (EIS) – Thermal evaluation of combined liquid and solid components Part 1: General requirements:
IEC 62332-2: Electrical insulation systems (EIS) –Thermal evaluation of combined liquid and solid components – Part 2: Simplified test:
Because of the cost and time aspects it is recommended to use IEC 62332-2.
3B. The IEEE test method
The test method presented in IEEE C57.100 is for the evaluation of the EIS for use in an OFT. The main body of C57.100 describes the general procedure for the evaluation. Annex A, B and C provide the details including two options of test specimens. Annexes A and B use a simpler test specimen and test methodology. Annex C is more complex and should be considered when the simpler approach of annexes A and B are not considered to be sufficient.
The recommended Step 3 is to start only one elevated temperature. After a predetermined and agreed upon time of heat exposure at the selected aging temperature, the project can be evaluated to decide if the project should be expanded to three temperatures or if the results are sufficient to complete the needed evaluation.
Step 3 can be described as a Screening Test.
Step 4: Completion of the Full Three Temperature Evaluation
Step 4 is the completion of a full LTTA by expanding the Screening Test from either IEC 62332-2 or IEEE by adding two additional aging temperatures. This expansion is also described in IEEE C57.100 in Annexes A with B or in Annex C.
Due to cost and time needed to build test specimens and test apparatus, ELTEK Labs recommends using IEC 62332-2.