In the field of electrical safety testing, the PTI and CTI tracking index tester is a crucial equipment for ensuring the reliability and safety of electrical equipment. Firstly, it can simulate the harsh environments that electrical equipment may encounter during actual operation. By doing so, it detects the ability of materials to resist tracking leakage, effectively preventing electrical failures and safety accidents caused by tracking leakage.
1. Main Standard
The tracking index test apparatus is mainly designed according to IEC60112. The IEC 60112 is a widely recognized international standard for evaluating the comparative tracking index (CTI) and the proof tracking index (PTI) of solid insulating materials under humid conditions. The standard elaborately specifies the technical requirements of the test device, the formula and concentration of the solution, the shape and size of the electrodes, the test procedures, and the result judgment methods. It also meet the requirements of UL746A, GB.T4207, GB4706.1 and TMD 3628-92 standard.
2. The meaning of CTI and PTI
CTI, names comparative tracking index, is the numerical value of the maximum voltage at which five test specimens withstand the test period for drops without tracking failure and without a persistent flame occurring and including also a statement relating to the behaviour of the material when tested using the surface of the material can withstand 50 drops of drops.
PTI, names Proof Tracking Index, is the numerical value of proof voltage in volts at which five test specimen withstand the test period for drops without tracking failure and without a persistent flame occurring.
3. Working Principle
The working principle of the tracking leakage test device is based on applying a certain voltage and specific electrolyte to the surface of the insulating material, simulating actual working conditions such as humidity and contamination. When the voltage is applied to the material surface, the electrolyte will form a conductive path under the action of the electric field, triggering a leakage current. As the test progresses, the heat generated by the leakage current gradually damages the molecular structure of the insulating material, resulting in carbonized traces on the material surface, that is, tracking leakage. Subsequently, we can evaluate the tracking – resistance performance of the material by observing and measuring the degree and development of the traces on the material surface.
4. Device Structure
Test Electrodes: Consisting of two electrodes with specific shapes and sizes, the size of the electrodes is 2mm±0.1mm)×(5mm±0.1mm)×(40mm±5mm), length≥12mm, and with an angle of chisel-edged: 30°±2°. It usually made of platinum with a minimum purity of 99%. These electrodes ensure stable voltage application and good contact with the material surface during the test.
Solutions Dripping System: It precisely controls the dripping speed and amount of the solutions, guaranteeing the consistency and accuracy of the test conditions. Commonly, the solution is an ammonium chloride solution with a certain concentration, Solution A: 0.1%NH4Cl, 3.95±0.05Ωm, solution B: 1.98±0.05Ωm.
Voltage Control System: This system can adjust the output voltage to meet the testing requirements of different materials and standards. Generally, the voltage range is between 100V – 600V.
Test Container: Used to place the test samples, it consists of insulating materials to prevent external environmental interference with the test results.
5. Operation Steps
Sample Preparation: First, make the material to be tested into samples of specified sizes and shapes, and ensure that the sample surface is clean and flat.
Device Debugging: Then, check whether the test electrodes, solution dripping system, voltage control system, etc. are working properly, and set the parameters required for the test, such as voltage, solution dripping speed, and dripping amount.
Sample Installation: Next, place the sample in the test container, adjust the contact position and pressure between the test electrodes and the sample surface to ensure a good electrical connection.
Test Start: Start the device, begin to drip the solution and apply the voltage.
Test End: When reaching the predetermined test time or obvious trace phenomena appear on the sample surface, stop the test, turn off the device, and save the test data and records.
6. Application Fields
Electronics and Electrical Appliance Industry: Widely used in the detection of insulating materials for various electronic and electrical products, such as plastic housings, connectors, circuit boards, etc., to ensure the electrical safety performance of products in complex environments.
Power Equipment Manufacturing: It can test the insulating components of high – voltage switches, insulators, transformers, etc. in power equipment, safeguarding the stable operation of the power system.
Automotive Manufacturing: During the design and production of automotive electrical systems, conduct tracking leakage tests on various insulating materials and components to improve the electrical safety and reliability of vehicles.
Aerospace Field: Strictly test the electrical insulating materials of aerospace equipment to ensure the safe operation of equipment in extreme environments.
7. Maintenance Points
Regular Cleaning: After the test, promptly clean the test electrodes, test container, and electrolyte dripping system to prevent the remaining electrolyte from corroding the equipment.
Check Electrode Wear: Regularly check the wear condition of the test electrodes. If there are obvious signs of wear or deformation on the electrode surface, replace them in a timely manner to ensure the accuracy of the test results.
Calibrate the Voltage System: Periodically calibrate the voltage control system to ensure the accuracy and stability of the output voltage.
Storage Precautions: Store the equipment in a dry and ventilated environment, and avoid damage to the equipment caused by direct sunlight and a humid environment.
In conclusion, the tracking leakage test device plays an important role in ensuring the safe operation of electrical equipment. By accurately evaluating the tracking – resistance performance of materials, it provides strong technical support for the design, production, and quality control of electrical products, contributing to the improvement of the safety level of the entire electrical industry. With the continuous progress of technology, the tracking leakage test device will also be continuously upgraded and improved to better meet the increasingly stringent electrical safety standards and market demands.
