In the context of
lugs and
connectors, a tensile test on UTM can be used to evaluate the performance of these components under different loads and conditions. Lugs and connectors are often used to join two or more structural elements together, and their ability to withstand tensile loads is an important factor in their design and selection. By subjecting lugs and connectors to tensile testing on UTM, engineers and designers can better understand the behaviour of these components under load and determine their suitability for a given application.
There are a variety of different techniques and methods that can be used to perform tensile testing on lugs and connectors using a UTM. The specific approach will depend on the type and size of the component being tested, as well as the desired outcome of the test. In general, however, tensile testing on UTM involves preparing the sample for testing, applying a tensile load to the sample, and measuring the response of the sample under that load. By analysing the results of the tensile test, engineers and designers can gain valuable insights into the
mechanical properties of lugs and connectors and use that information to improve their design and performance.
IEC 61238
IEC 61238-1- “Compression and mechanical connectors for power cables for rated voltages up to 30 kV” is a standard published by the International Electrotechnical Commission (IEC) that provides guidelines for the testing and evaluation of cable lugs and connectors. The IEC 61238 standard covers a wide range of topics related to the design, manufacturing, testing, and performance of lugs and connectors, including requirements for tensile testing. The standard covers connectors for power cables with rated voltages up to 30 kV (Um = 36 kV) and conductors with cross-sectional areas of 2.5 mm2 or greater for copper and 16 mm2 or greater for aluminium, and a maximum continuous conductor temperature not exceeding 90°C. It is not applicable to connectors for overhead conductors and connectors with sliding contact or multi-core connectors. The standard also specifies the type of test methods and requirements that apply to compression and mechanical connectors for power cables with copper or aluminium conductors.
Equipment Needed for Tensile Testing
1. UTM Machine: A UTM is a mechanical testing instrument that is used to apply tensile, compressive, and other types of mechanical loads to a sample and measure the response of the sample under that load
2. Grips or fixtures: These are used to hold the sample in place during the tensile test and apply the tensile load to the sample. The type of grip or fixture used will depend on the size and shape of the sample being tested.
Tensile Testing Procedure as per IEC 61238
According to IEC 61238, tensile testing of lugs and connectors is used to determine the tensile strength and elongation of the material under test. The standard specifies that tensile testing should be performed using a universal testing machine (UTM) or other suitable devices that is capable of applying a tensile load to the sample. The standard also outlines the requirements for the preparation of the sample, the loading rate, the test conditions, and the calculation of the test results.
Here’s the step-by-step procedure:
1. Prepare the sample for tensile load testing by crimping it to a suitable cable size dependent on the inner diameter of the lug. 2. Now fix this crimped sample on the Universal Tensile Testing Machine (UTM). 3. Switch “ON” the UTM machine and set the required parameters for testing which are the Speed & Load Application Rate. 4. Set the required tensile load value and duration to apply the tensile load as per table 4 of IEC 61238.
5. Close the protective door to avoid any accidents.
Note – Do not stand in front of the machine, stay away from the mounted sample as it can eject the broken particles of the tested sample. 6. Enter the load value which needs to be applied for 1 min. 7. After the test, the machine will stop automatically. Once the test is done, remove the sample and check whether the conductor has slipped from the lug or not. 8. If the conductor slips from the lug or the slippage exceed the specified length, then the sample does not comply with the standard. In addition to tensile testing, IEC 61238 also includes requirements for other types of testing that may be performed on lugs and connectors, such as bending, torsion, and impact testing. These tests are used to evaluate the performance of lugs and connectors under different loads and conditions and to ensure that they meet the required mechanical and electrical performance standards.
Why is Tensile Testing important for Lugs?
Lugs and connectors are critical components that are used to join two or more structural elements together. They are subjected to various types of loads and stresses during their service life, and their ability to withstand these loads and stresses is an important factor in their design and selection. Testing is an essential part of the design and evaluation process for lugs and connectors, as it allows engineers and designers to understand the behaviour of these components under different loads and conditions and to determine their suitability for a given application. If lugs and connectors are not tested according to the appropriate standards and guidelines, there is a risk that they may not perform as intended or may fail under load. This can have serious consequences, depending on the application. In the case of lugs and connectors used in electrical applications, such as in
power transmission and distribution systems, failure of these components can result in electrical outages or other types of electrical incidents. This can disrupt critical services, and infrastructure and may pose a risk to human safety.
Conclusion
In conclusion, tensile testing is an important method for evaluating the mechanical properties of lugs and connectors. By following the guidelines outlined in IEC 61238, manufacturers and users can ensure that their lugs and connectors are tested in a consistent and reliable manner and that the test results accurately reflect the mechanical properties of the material.
