Power frequency voltage breakdown testerIt is a specialized equipment used to test the ability of insulation materials (such as plastics, rubber, ceramics, insulating oil, etc.) to withstand power frequency voltage, widely used in the fields of electrical engineering, material testing, etc. Its core function is to evaluate the insulation performance of materials by applying gradually increasing power frequency AC voltage to determine the breakdown voltage value of materials under specified conditions.
1、 Core components of equipment
To understand the working principle, it is necessary to first clarify the core components of the equipment, and the various components work together to complete the testing process:
Boosting system: including a boosting transformer and a voltage regulating device, it is the core that provides the test voltage. The step-up transformer can convert the low voltage of the power frequency (such as 220V/380V) into the high voltage required for testing (up to tens of thousands of volts or even higher); The voltage regulator is used to control the rate of voltage rise and fall and the output value.
Electrode system: divided into high-voltage electrodes and grounding electrodes, different shapes of electrodes (such as spherical, flat plate, needle shaped) can be selected according to testing standards (such as GB/T 1408). The sample is clamped between two electrodes, and the test voltage is applied at both ends of the electrodes.
Control system: composed of a controller, voltage acquisition module, and timing module, used to set test parameters (such as boost rate, test duration), collect real-time voltage data, and control the start stop of the boost process.
Protection system: including overcurrent protection, overvoltage protection, and breakdown protection. When the sample breaks down, the test circuit can be quickly cut off to prevent equipment damage and personnel electric shock.
2、 Basic working principle
The working logic of the power frequency voltage breakdown tester follows the process of "voltage application withstand voltage detection breakdown judgment", as follows:
The sample clamp prepares the insulation material to be tested into a sample according to standard requirements, and places it flat between the high-voltage electrode and the grounding electrode to ensure good contact between the electrode and the sample, without bubbles or gaps. For solid materials, it is necessary to ensure uniform sample thickness; For liquid materials (such as insulating oil), they need to be poured into a dedicated electrode cup to eliminate internal bubbles.
Parameter setting is achieved through the control system setting of experimental parameters, with core parameters including:
Boosting rate: refers to the speed at which the voltage rises (such as 1kV/s, 2kV/s), and different materials and standards have clear regulations on the boosting rate;
Voltage endurance time: If it is a voltage endurance test, the holding time of the sample at a certain voltage needs to be set;
Protection threshold: Set the maximum test voltage and maximum current to prevent equipment overload.
After the boosting and detection start test, the voltage regulator drives the step-up transformer, increases the output voltage step by step at the set rate, and applies it to the samples at both ends of the electrode.
During this process, the voltage acquisition module monitors the applied voltage value in real-time, while the current acquisition module monitors the leakage current in the circuit.
If it is a voltage withstand test: after the voltage rises to the set value and remains constant, the timing module starts timing. If the sample does not break down within the specified time, it is judged that the voltage withstand of the sample is qualified.
If it is a breakdown test: the voltage continues to rise until the sample cannot withstand the voltage and insulation damage occurs.
When a sample experiences breakdown, the following characteristics will appear:
The leakage current in the circuit increases sharply, exceeding the protection threshold;
Discharge and breakdown points occur between electrodes (solid materials may show perforation and carbonization marks).
At this point, the protection system will immediately cut off the test circuit, and the control system will record the voltage value at the moment of breakdown. This value is the breakdown voltage, which can be used to calculate the breakdown field strength of the material (breakdown field strength=breakdown voltage/sample thickness).
3、 Core principle essence
The breakdown of insulating materials is essentially caused by the acceleration of charged particles (electrons, ions) inside the material under the action of a strong electric field, which collide with lattice atoms and trigger avalanche ionization, resulting in the loss of insulation properties of the material, transforming from an insulator to a conductor, forming a conductive channel, and ultimately leading to breakdown.Power frequency voltage breakdown testerThe core of it is to simulate the power frequency electric field environment that materials can withstand in actual working conditions, accurately capture the critical voltage at which materials break down through through controllable boosting, and quantitatively evaluate the insulation ability of materials.
4、 Test precautions
The experiment needs to be conducted in a dedicated high-voltage laboratory, and the operator must wear insulated gloves, stand on an insulated pad, and strictly follow the high-voltage operation specifications.
Before the experiment, it is necessary to check the cleanliness of the electrode. Stains and rust on the surface of the electrode can affect the test results.
The preparation of samples must comply with standard requirements, and excessive deviations in thickness and size can lead to data distortion.