What is a Partial Discharge-Free (PD-Free) Test Transformer?

What is a Partial Discharge-Free (PD-Free) Test Transformer?

A partial discharge-free (PD-free) test transformer is a specialized testing device used to assess the insulation condition of high-voltage electrical equipment. Partial discharge refers to small electrical discharges that occur within weak points of an insulation system. It often serves as an early indicator of insulation aging or damage. If left unchecked, partial discharge can gradually deteriorate the insulation, eventually leading to equipment failure.

The unique feature of PD-free test transformers is that they produce very low levels of partial discharge themselves (typically below 5 picocoulombs, or pC). This low PD level ensures that the transformer doesn’t interfere with the partial discharge readings of the equipment being tested, thus providing accurate results.

Main Types of PD-Free Test Transformers

1. Gas-Insulated PD-Free Test Transformers: Use gases, like SF₆ or nitrogen, as insulation to minimize partial discharge.
2. Oil-Immersed PD-Free Test Transformers: Use insulating oil to protect and cool the transformer, controlling partial discharge effectively.

Primary Applications of PD-Free Test Transformers

PD-free test transformers are essential for:

• Withstand Voltage Testing: Verifying the insulation strength of equipment under high-voltage stress.
• Partial Discharge Testing: Detecting weak points in insulation without interference from the test transformer itself.
• Research and Development: Ideal for developing high-voltage equipment where accurate partial discharge data is critical.

How to Select PD-Free Test Equipment

1. Determine Test Voltage Requirements: Select a PD-free test transformer that matches the rated voltage of the equipment you are testing. For equipment rated up to 35kV, use a test transformer designed for that voltage range.

2. Partial Discharge Level: Choose a transformer with a partial discharge level below 5 pC. Lower PD levels prevent the test transformer from influencing the test results.

3. Type of Transformer: Select between gas-insulated or oil-immersed based on the testing environment and maintenance needs. Gas-insulated transformers are compact and portable but may require gas maintenance, while oil-immersed transformers offer stability and are ideal for long-term use.

4. Quality Control and Accuracy: Look for equipment from manufacturers with strict quality control processes, ensuring long-term reliability and accuracy for precise testing results.

5. Budget and After-Sales Support: Since PD-free test equipment is highly specialized, consider the manufacturer's after-sales support and technical assistance options to ensure timely help during use.