3 August 2023
Special tests are a crucial step for companies engaged in transformer production. At Trans-El, we are committed to providing our customers with high-quality and reliable products. Therefore, we conduct these tests to verify the performance and durability of our products.
These tests allow us to examine the specifications and functionality of transformers in more detail. They assess whether transformers comply with safety standards, their efficiency, insulation condition, and other critical features.
For example, the Capacity and Insulation Loss Factor Measurement (Doble Test) is used to determine the insulation condition and calculate the insulation loss factor of transformers. This test provides essential information about the transformer’s insulation condition and is an experiment that needs to be continuously monitored.
Insulation resistance measurement (Megger test) is a widely used test to evaluate the insulation resistance of transformers. This test provides information about the transformer’s insulation condition and is considered a crucial indicator for the transformer’s long-term use.
Noise spectrum analysis allows the examination of the noise generated by transformers during operation. This test is vital for determining and controlling the noise level. At Trans-El, we adopt a meticulous approach to noise levels and use noise spectrum analysis to ensure our products operate more quietly.
These tests are an essential step in our commitment to providing more reliable and high-quality transformers to our customers. At Trans-El, we continually stay up-to-date with new technologies and testing methods and use the latest test equipment to ensure the excellence of our products. By prioritizing customer satisfaction, we continue to strive to be a leading company in the industry.
Capacity and Insulation Loss Factor Measurement (Doble Test)
The Capacity and Insulation Loss Factor Measurement (Doble Test) is a significant test within the scope of special tests that Trans-El uses to evaluate the insulation condition of our transformers and calculate the insulation loss factor.
In practice, we understand that insulation materials used in transformer manufacturing do not provide absolute insulation. They allow small leakage currents during operation, leading to insulation losses. While these losses may not be significant compared to the transformer’s no-load and load losses, measuring them and calculating the insulation loss factor provides valuable information about the transformer’s insulation condition.
The loss angle varies depending on factors such as the thickness and surface of the insulation material, ionization, foreign substances and particles, and air gaps. Therefore, loss angle measurements provide crucial results for evaluating the insulating properties of insulation materials.
Capacity and insulation loss factor measurements are performed on equivalent capacities between windings and between windings and the tank. During this process, the upper oil temperature of the transformer is measured, and the measured values are adjusted according to the reference temperature. This allows us to obtain more precise and reliable results regarding the transformer’s insulation condition.
The Capacity and Insulation Loss Factor Measurement (Doble Test) enables us to confirm that our transformers are equipped with high-quality insulation materials and provide robust insulation even during long-term use. At Trans-El, we regularly repeat this test to keep the insulation condition of our transformers under continuous control. Our goal is to provide reliable and durable transformers to our customers, and through special tests, we aim to maintain the performance and quality of our products at the highest level.
Insulation Resistance Measurement (Megger Test)
Insulation Resistance Measurement (Megger Test) is an essential test among special tests used by Trans-El to gain information about the insulation condition of our transformers. It is a widely used and valuable experiment.
Insulation resistance measurements are performed using devices called Meggers, which are generally more affordable and easy to use compared to other measuring instruments. Megger devices come in three different types: dynamo, battery-operated, and motor-driven, producing DC voltage at various voltage levels.
Measurements are typically conducted with dynamo and battery-operated Meggers for a duration of 1 minute. During this time, values are read and recorded every 15 seconds. Additionally, during the test, the upper oil temperature of the transformer and the humidity level in the air (if measurable) are measured and recorded.
Once the test is completed, the measured values are corrected to the reference temperature of 20°C. The final value measured at the 60th second is used to calculate a parameter called the Polarization Index, which is obtained by dividing the value measured at the 60th second by the value measured at the 30th second. This parameter is used to make assessments about the transformer’s insulation condition.
Motor-driven Meggers typically conduct measurements over a 10-minute period, with values recorded each minute. The Polarization Index is calculated by comparing the value measured at the 10th minute to the value measured at the 1st minute.
During insulation resistance measurements, it is important to know the transformer’s insulation level and its upper voltage. The test voltage should be selected accordingly. Additionally, the transformer bushings should be dry and clean during the test. If there are YG and AG windings, copper conductors, including neutral ends, should be bridged.
Measurements are conducted between YG-AG, YG-TANK, AG-TANK, and, if the core grounding terminal is exposed, between CORE-TANK. The (-) and (+) polarity terminals of the Megger device are connected separately to the pair of terminals to be measured. The guard (shield) terminal is connected to the open terminal. Measurements are performed as described above.
For more detailed information about special tests, you can visit the official Trans-El website.
- High Voltage Transformer Repair, Maintenance, and Restoration
- The Importance of Transformer Repair, Maintenance, and Service
- Transformer (Trafo)
- Power Transformer
- Tip Test and Temperature Rise Test
- Tip Test and Measuring Audible Noise Level
- Special Tests
- Induced Voltage Test for Transformers
- Short-Circuit Test