The core working principle of the insulator tensile testing machine is to accurately apply axial tensile loads, simulate the actual stress state of insulators in transmission lines, measure their mechanical properties throughout the entire process from stress to failure, and evaluate the tensile strength and structural reliability of insulators. The workflow can be divided into four core stages: clamping and positioning, load application, data acquisition, and result judgment, as follows:
1、 Clamping positioning: Ensure precise coaxial force bearing
The clamping of insulators is the basis for ensuring testing accuracy, and it is necessary to strictly align the axis to avoid eccentric force:
Select specialized fixtures based on the type of insulator (ceramic, glass, composite) and hardware structure: ceramic/glass insulators use hard alloy fixtures with compatible hanging rings, while composite insulators use fixtures with flexible sheaths to prevent damage to the silicone rubber sheath.
Fix the upper end fittings of the insulator on the upper fixture and the lower end fittings on the lower fixture. Use the adjustable positioning device of the fixture to ensure that the axis of the insulator coincides with the loading direction of the equipment, and the coaxiality error is less than or equal to 0.002mm.
When clamping the fixture, the force should be moderate. If it is too tight, it will damage the fittings, and if it is too loose, it will cause slippage during testing. The clamping force should be adjusted according to the rated load of the insulator to ensure that the clamping is firm and does not damage the specimen.
2、 Load application: Simulate actual stress conditions
According to the testing purpose (rated load verification/failure strength testing), different loading modes are set by the control system to accurately apply tensile loads:
Rated tensile load test: Using load control mode, according to GB/T 1001.1, IEC 60383 and other standards, load the rated tensile load of the insulator at a constant rate (such as 100kN, 500kN), and then maintain the load for 1-5 minutes to simulate the condition of the insulator bearing the tension of the wire for a long time. Observe whether the insulator deforms, the fittings loosen, the sheath cracks and other abnormalities occur.
Destructive strength test: Using speed control mode, apply tensile load at a set speed (such as 1-50mm/min) at a constant speed until the insulator breaks, the hardware is damaged, or the load drops to 50% of the peak value. Simulate the failure process of the insulator under load (such as typhoon, wire breakage) and accurately capture the maximum destructive load.
During the loading process, closed-loop control of the load is achieved through servo valves (hydraulic type) or servo motors (electronic servo type) to ensure that the load fluctuation is ≤± 1%, simulating the stability of real force.
3、 Data collection: Record mechanical parameters throughout the process
By using a high-precision measurement system, key data such as load and displacement can be collected in real time, and the deformation process of insulators under stress can be fully recorded
The force sensor (accuracy level 0.5/0.3) collects real-time tensile load data with a resolution of up to 0.01kN, accurately capturing subtle changes in the load, especially the peak load at the moment of failure.
The large stroke displacement sensor (resolution 0.001mm) records the overall tensile deformation of the insulator. For scenarios where small deformations need to be measured, an extensometer can be used to accurately measure the relative displacement between the metal fittings and the insulator body.
The data collection frequency is ≥ 500Hz to ensure the complete capture of the entire process data from elastic deformation, yielding to failure. The control system converts the load and displacement data into load displacement curves, which are displayed in real-time on the operation interface.
4、 Result judgment: automatic calculation and compliance assessment
After the test is completed, the system automatically analyzes the data and generates test results and compliance reports:
When the preset termination conditions are reached (end of load holding time, insulator damage, load drop to 50% peak), the equipment automatically stops loading, the hydraulic system unloads or the servo motor stops, and the fixture automatically releases.
The control system automatically calculates key indicators based on the collected data:
Rated load verification: Determine whether the insulator is undamaged and deformed under rated load, and meets the standard requirements.
Destructive strength test: Calculate the destructive load and deformation, evaluate the tensile safety factor of the insulator (destructive load ÷ rated load), usually requiring a safety factor of ≥ 2.5.
The software automatically generates test reports that comply with the standards of the power industry (GB/T 1001.1, IEC 60383), including sample information, test parameters, load displacement curves, key indicators, and compliance determination results.
5、 Core technological advantages and principle adaptability
Coaxiality control: By using specialized fixtures and positioning devices, the force axis of the insulator is ensured to be consistent with the loading direction, avoiding testing errors caused by eccentric stress and conforming to the actual stress state of the insulator in the transmission line.
Precise load control: Adopting a closed-loop control system, the load accuracy is ≤± 0.5%, which can accurately simulate the tensile load under different working conditions and meet various requirements such as rated load maintenance and failure strength testing.
Data integrity: High frequency data collection ensures the capture of mechanical parameters at the moment of damage, providing complete data support for the quality assessment and failure analysis of insulators.