The voltage breakdown tester simulates an electric field environment and applies gradually increasing voltage to insulating materials until breakdown occurs, in order to determine their dielectric strength - the maximum electric field strength (unit: V/mm) that the material can withstand without breakdown. The core principles and operating procedures are as follows:

1、 Experimental principle: Critical relationship between electric field strength and dielectric breakdown

When the electric field strength exceeds the withstand voltage of the insulating material, the material will experience breakdown, manifested as a sudden increase in current and a sudden drop in voltage. The tester applies high voltage (AC or DC) to record the critical voltage value at which the material breaks down, and calculates the dielectric strength based on the sample thickness (formula: dielectric strength=breakdown voltage/sample thickness). For example, if a 1mm thick plastic sample breaks down at 30kV, its dielectric strength is 30kV/mm.

2、 Experimental process: Full chain control from preparation to results

Sample preparation:

Ensure uniform sample thickness and avoid errors caused by uneven electric field distribution.

Clean the surface of oil and dust to prevent premature breakdown caused by local electric field concentration.

Pre treat materials that are prone to water absorption, such as cable paper, by drying or impregnating them to eliminate the influence of moisture.

Device settings:

Select the test type (power frequency AC, DC, or pulse surge), set the boost rate (such as 200V/s-5000V/s), boost time (such as 1 minute), and upper limit of leakage current (such as 3.5mA).

Configure test electrodes (such as metal foil, ball electrodes) to ensure good contact with the sample.

Experimental execution:

Start the device, slowly increase the voltage from zero to the set value, and maintain it for the specified time.

Real time monitoring of voltage and current changes, automatically cutting off power and recording data when breakdown occurs.

3、 Key influencing factors: Multi dimensional control ensures the reliability of results

Temperature: High temperatures accelerate the movement of material molecules and reduce dielectric strength. The experiment needs to be conducted at standard temperature (such as 23 ℃) or simulated environment (such as -40 ℃ to 300 ℃).

Humidity: A humid environment can reduce insulation performance, and the test should be conducted in an environment with a relative humidity of 50 ± 5%.

Sample thickness: Uneven thickness can lead to uneven distribution of electric field, and it is necessary to measure the thickness at multiple locations and take the average value.

Electrode shape: Different electrodes (such as equal diameter or unequal diameter) can affect the distribution of electric field, and should be selected according to standards.