What Is an Electrical Inspection?
Verification of various performances that low voltage electrical appliances should have under normal working and fault conditions. The test items of low-voltage electrical appliances mainly include general inspection, voltage drop measurement, temperature rise test, insulation resistance and withstand voltage test, rated making and breaking capacity test, short-circuit making and breaking capability test, short-time withstand current capability test, action Characteristic test, life test, immunity test, characteristic test, etc. The equipment and test methods for low-voltage electrical testing have many similarities to the high-voltage electrical testing. Most of the low-voltage electrical tests in some countries in the world are attached to high-voltage electrical test stations, and high-voltage and low-voltage electrical tests can share the test power. Most of China is an independent low-voltage electrical appliance test station, which uses the grid as a test power source through a transformer.
Low-voltage electrical testing
Right!
- Verification of various performances that low voltage electrical appliances should have under normal working and fault conditions. The test items of low-voltage electrical appliances mainly include general inspection, voltage drop measurement, temperature rise test,
- Including appearance inspection; inspection of external dimensions and installation dimensions of electrical appliances; inspection of electrical clearances and creepage distances; inspection of contact opening distance, over-stroke and pressure; inspection of electrical appliance operating forces, etc. The gap of an electrical appliance refers to the minimum air insulation distance between different poles or between two conductive circuits after one pole is broken. Creepage distance refers to the creepage distance along the surface of the insulator that supports and fixes between different poles or between two conductive circuits after one pole is disconnected. When the surface of electrical insulators absorbs moisture, is heated, or is contaminated, its surface resistance drops sharply. In order to ensure a certain insulation performance of electrical appliance insulation, the minimum electrical clearance and surface creepage (creepage) distance are specified in the electrical appliance design according to the voltage level and the place of use. Contact opening distance refers to the shortest distance between the contacts when the electrical contacts are in the off position. Contact over-travel is to ensure that the contacts are reliably closed after the electrical contacts are worn to some extent during operation. For manually operated appliances, check the operating force to check whether the operating force meets the requirements of manual operation.
- After the measuring contact or conductive circuit is passed a DC current, the voltage drop across the measured part. The purpose of the measurement is to evaluate the resistance value at both ends of the measured part, and use the magnitude of the resistance value to indirectly judge the assembly quality and heating temperature rise of the appliance. For example, for the contacts of small relays, it is generally not possible to measure the temperature of the contacts with a thermocouple, but to measure the voltage drop across the contacts.
- Temperature rise test
- It is used to verify whether the electrical components are within the allowable temperature rise range after they are heated and stabilized. Contacts, wires, copper bar terminals of different appliances,
- Testing institutions: National Industrial Electrical Product Quality Supervision and Inspection Center, Suzhou Electrical Appliance Research Institute, National Electrical Product Quality Supervision and Inspection Center, etc.