Capacitance and dissipation factor tests are essential diagnostic tools for power transformers. These tests help to determine the transformer's insulation condition, which is important to prevent unexpected failures and to improve the transformer's performance and lifespan.
Capacitance is a measure of the transformer's ability to store electrical charge at a particular voltage. The test involves measuring the capacitance between each winding and ground, as well as between individual windings. A change in capacitance over time can indicate insulation aging or the presence of moisture or other contaminants inside the transformer.
Dissipation factor, also known as tan delta, measures the power loss in the insulation material. This loss can cause heat and damage to the transformer, so it's important to monitor the level of dissipation factor. The test involves applying an AC voltage to the transformer and measuring the ratio of the power lost to the energy stored in the insulation.
Both capacitance and dissipation factor tests can be performed simultaneously using specialized test equipment. This equipment generates a low-frequency AC voltage and measures the current and phase angle between the transformer windings. By comparing the capacitance and dissipation factor values to industry standards, technicians can determine the transformer's overall insulation condition.
A transformer's insulation can deteriorate over time due to thermal cycling, moisture, and other environmental factors. In addition, manufacturing defects or improper installation can cause insulation problems from the outset. Insulation failures can lead to costly downtime, transformer damage, and even hazardous conditions for workers and equipment.
By regularly performing capacitance and dissipation factor tests, transformer owners and operators can gain valuable insight into the health of their equipment and take proactive steps to prevent failures. For example, if the tests reveal a high dissipation factor, the transformer could be oil purged, dried, or re-insulated to improve its performance. Similarly, if the capacitance values are changing over time, it could indicate that the transformer is at risk of failure and requires closer monitoring.
HUAYI developed the capacitance and dissipation factor tester which has multiple test modes：It can test by internal high voltage, external high voltage, internal standard,external standard, positive connection method, reverse connection method, self-excitation method and other methods;High voltage (> 10kV) dielectric loss can be made under the condition of external standard external high voltage. With CVT test：can test CVT(capacitor voltage transformer)C1/C2 of dielectric loss and capacitance, can test C1/C2 simultaneously. Can also test CVT Variation ratio and voltage Angle difference
Capacitive and dissipation factor tests are essential tools for ensuring the reliable and safe operation of power transformers. By monitoring the insulation condition and identifying potential problems before they become critical, transformer owners and operators can save money, time, and prevent hazardous situations.