Withstand voltage testing is an important method for checking the insulation performance of motor windings or coils during motor manufacturing. This includes withstand voltage tests on wound cores, formed coils, and complete motor products. During the test, for different test conditions and winding types, in addition to the requirements for the applied voltage peak value, special emphasis must be placed on the construction and control of the ground.
During the overall machine testing, it is essential to ensure reliable grounding of the casing, meaning the casing must be tightly connected to the ground wire. For withstand voltage tests on wound iron cores, it is crucial to ensure good contact between the iron core and the ground wire. However, for withstand voltage tests on molded winding coils of low-voltage, high-power, and high-voltage motors, a relatively suitable ground must be created. Different companies employ different methods. For instance, some companies wrap the straight edges of the coil with tin foil and then connect the outer tin foil to the ground wire; others use the steel ball method, embedding the straight edges of the coil in steel balls and ensuring good contact between the steel balls and the ground wire.
Different testing methods operate on the same underlying mechanism. It is particularly important to emphasize that the grounding of the grounding wire should be checked regularly, and testing personnel should strictly adhere to labor protection measures to ensure the safety of the testing process.
The grounding wire is the lifeline.
Grounding wires in power systems are essential tools for protecting workers in the event of unexpected voltage spikes on de-energized equipment and lines. Grounding wires must be made of bare copper stranded wire with a cross-sectional area of at least 25 mm².
The grounding wire is the wire that is directly connected to the earth. It can also be called the safety return line. In case of danger, it directly transfers the high voltage to the earth, so it can be considered a lifeline.
Household appliances, due to poor insulation or humid environments, can develop static electricity on their casings, which can lead to electric shock in severe cases. To prevent this, a wire can be connected to the metal casing of the appliance, with the other end grounded. If the appliance leaks electricity, the grounding wire will carry the static electricity to the earth and discharge it. Additionally, it's important to note that when repair technicians use soldering irons, the soldering iron may sometimes be electrified and damage integrated circuits within the appliance.
Computer users sometimes overlook grounding the computer case. In fact, connecting a ground wire to the computer case can prevent system crashes to some extent.
In household appliances, reputable manufacturers use three-prong power plugs, one of which is the grounding wire. Of course, this is common knowledge for those who work with motors.
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