Various Of Breakdown Voltage Testers – Widely Used With Different Functions

Various Of Breakdown Voltage Testers – Widely Used With Different Functions


Electricity flowing through transmission lines, transformers and other high voltage equipment can face breakdown events if the insulation is faulty or fails over time. To test the integrity of insulation systems and ensure safe operation, various types of breakdown voltage testers are used in the industrial and utility sectors. In this blog post, we will explore the workings of different breakdown voltage testers, their applications and importance in maintaining electrical assets.

Breakdown voltage refers to the maximum voltage a material can withstand before its insulation breaks down, allowing current to flow through. Every insulating material has a specific breakdown voltage depending on thickness and other factors. Routine testing helps determine if the withstand strength has reduced below design limits due to aging, contaminants or defects. Let’s examine some commonly used breakdown voltage tester.

Transformer Breakdown Voltage Tester

One of the most widely used pieces of test equipment is the transformer breakdown voltage tester. As the name suggests, it is primarily used to test the integrity of transformer winding insulation and bushings. In this type of tester, a step-up transformer is used to safely generate high voltages from lower mains voltage. The test voltage is applied in stepped increments till breakdown occurs. The tester records the breakdown voltage value.

Transformer breakdown voltage testers allow non-destructive partial discharge testing of energized transformers in the field. They eliminate the need to take expensive units out of service. The portable units can test transformers of different ratings quickly and are easy to operate. Advanced digital units incorporate microprocessor controls for automated testing and documentation of results. Regular transformer insulation testing using these instruments helps spot deteriorating insulation well in advance to avoid catastrophic failures.

Oil Breakdown Voltage Tester

Besides solid insulation inspections, it is also crucial to check the dielectric strength of transformer insulating oil. For this purpose, oil breakdown voltage testers are employed. In these instruments, the oil sample under test is placed between electrodes in a cell chamber. The voltage is then raised gradually until breakdown happens across the oil gap.

Some key types of oil breakdown voltage tester include flask testers, cylinder testers and diaphragm testers. Flask testers use a ground glass stopper assembly between two pipe-shaped electrodes. Cylinder testers contain cylindrical electrodes along the vertical length of an insulation chamber. Meanwhile, diaphragm testers utilize a flexible non-conductive diaphragm that maintains uniformity of the electric field across the test volume.

Accurate oil testing is necessary to detect moisture and particulate contamination that can lower the breakdown strength over time. Oil testers enable determination of maintenance intervals and oil reconditioning needs. They play an important role in condition monitoring programs for reliable transformer fleet management.

Insulation Breakdown Voltage Testers

Testing insulation integrity is equally critical for switchgears, cables and other high voltage apparatus. Different styles of breakdown voltage testers are used for such applications. Some commonly found models include electroded disc testers and floating ring testers.

Electroded disc testers consist of a sample holder kit and incorporate disk-shaped electrodes that apply the breakdown test voltage across the dielectric material. These testers are suitable for sheet insulation specimens in labs. On the other hand, floating ring testers contain ring or ball shaped electrodes supported on insulating materials. They are useful for outdoor testing on cables, bushings and outdoor insulation like sorbent pads.

Partial Discharge Measurement

Partial discharge (PD) refers to a localized dielectric breakdown that does not terminate the insulation entirely. It is an early indicator of insulation degradation and eventual failure if not addressed. Partial discharge testers apply high frequency voltage pulses and employ ultra-high frequency sensors to detect PD activity inside test objects. Both portable PD testers and permanently installed PD monitoring systems help spot insulation issues in a preventive manner.

Overall, different types of breakdown voltage testers serve various applications in testing solid insulation as well as liquid dielectrics. They allow assessment of insulation health to ensure stabilized operation over the expected lifespan of electrical equipment like transformers operating at distribution and transmission voltages. Periodic diagnostic testing through such test instruments plays a key role in condition-based maintenance of power infrastructure. Their use helps avoid unexpected failures and minimize outage costs in industrial manufacturing plants and utility grids.