Performance test of terminal blocks and its methods and standards

     The appearance of the terminal block looks simple, but the terminal block must also undergo strict product verification tests and periodic production type experiments. This article mainly introduces the content, methods and judgment criteria of the mechanical performance, electrical performance and environmental performance tests of the terminal block.

　　1. Mechanical properties test

　　1. Tightening Torque Test

　　The purpose of the torque test is to test whether the screw has sufficient mechanical strength to ensure that there is no thread slippage during the crimping process. If the screw does not break or deform after the test, and the screw head slot does not have damage that affects continued use, it is qualified.

　　2. Wire pressing reliability test (Secureness Test)

　　The purpose of the wire crimping reliability test is to test whether the terminal can clamp the wire without excessively damaging the wire. Connect the terminal to the wire of the specified type and rated cross-sectional area, hang a certain weight, and rotate at a speed of 10 revolutions per minute (10±2r/min) for 15 minutes. After the test, if the wire does not slip out of the terminal clamping part or break near the clamping part, the wire crimping reliability of the terminal is qualified. If the wire breaks or falls off the clamping mechanism of the terminal, it is unqualified.

　　3. Pull Out Test

　　The purpose of the pull-out test is to test whether the terminal can firmly clamp the wire between the metal surfaces. Connect the wire of the specified type and rated cross-sectional area to the terminal, select a certain force (lkgf), pull the wire in the direction of the wire axis, and keep it for 1 minute. If the wire does not fall out of the terminal, it is qualified.

　　4. Mechanical Strength Test

　　The purpose of the mechanical strength test is to test whether the terminal has sufficient mechanical strength, especially whether the terminal shell has sufficient mechanical strength. During the test, a sample is placed in the drum of the test equipment and rotated at a speed of 5 revolutions per minute. After 5 minutes, the machine is turned off and the sample is taken out for observation. If the terminal is not damaged and the shell has no cracks or damage, it is qualified.

　　5. Mechanical life test (Fatigue Test)

　　The purpose of mechanical life test is to test whether the elastic element of the terminal can withstand a certain number of plugging and unplugging or other mechanical operations, such as the compression and release of the spring terminal button. If the elastic element after the test is assembled into the terminal, the mechanical and electrical performance should still meet the requirements, then it is qualified.

　　2. Electrical performance test

　　1. Contact resistance test (CONtact Resistance)

　　The contact resistance test is to test the static contact performance of the terminal, that is, the contact resistance should not be greater than a certain value.

　　2. Power-Frequency Withstand Voltage Test

　　The power frequency withstand voltage test is to test whether the terminal housing can withstand the specified transient or short-term power frequency overvoltage. During the test, no flashover or breakdown should occur.

　　3. Impulse Withstand Voltage Test

　　The impulse withstand voltage test is to test whether the terminal housing can withstand the specified transient overvoltage. There should be no destructive discharge during the test.

　　4. Voltage Drop Test

　　The voltage drop test is to test the dynamic contact performance of the terminal. The voltage drop should not be greater than a certain value.

　　5. Temperature Rise Test

　　The temperature rise test is to test the temperature rise of the terminal under normal use, and its temperature rise cannot exceed the specified value. Generally, the UL standard stipulates that the temperature rise of the terminal cannot exceed 30°C above the ambient temperature after the current passes through it.

　　6. High and low temperature electrical performance test (Electrical Performance Test)

　　The electrical performance test is to test the reliability of the electrical performance of the screwless terminal in normal use. After the terminal has been subjected to 192 cycles, the voltage drop in the 24th and last cycle shall not be greater than a certain value.

　　3. Environmental performance test

　　1. Vibration Test for Package

　　The package vibration test simulates the ability of the terminal package to withstand vibration during transportation. After the test, the terminals in the package must not be affected or damaged.

　　2. Vibration Test for Products

　　The product vibration test simulates the ability of the terminal to withstand vibration when in use. The front, back, left, right, top and bottom of the terminal are fixed on the vibration table in sequence, and the specified simulation value is applied to the X, Y, and Z axis directions of the terminal respectively. After the test, the terminal shall not be damaged.

　　3. Test for Flammability of Plastic Materials

　　The flame retardant test is to test the flame retardant performance of the terminal material. During the test, the standard sample is clamped on the clamping seat of the instrument test, and the fire source is moved to the specified position to ignite and burn for a specified time, and then the fire source is removed. If the sample is still burning after the fire source is removed, or its dripping ignites the cotton under the sample, the flame retardancy is unqualified. If the sample goes out by itself after the fire source is removed, the flame retardancy is qualified.

　　4. Resistance Aging Test

　　The aging test is to test whether the terminal can be used normally under a certain high temperature. The terminal is placed in an aging test box and subjected to a high temperature of 105℃ or 120℃ for 7 days. If the tested terminal does not age, it is qualified.

　　5. Damp Heat Test

　　The cyclic damp heat test is to test whether the terminals can withstand the humid conditions that may occur in normal use.

　　6. Salt Spray Test

　　The salt spray test is also used to test whether the terminal can withstand the humid conditions that may occur in normal use. It is only a separate test of the metal parts of the terminal. If the metal parts are rusted after the test, it is unqualified.