1. What is a safety test
First of all, we need to know what is a safety test? It conducts a series of safety performance tests by simulating the possible use of electrical products by customers. This type of test is called safety test.
2. The purpose of safety testing
Safety testing mainly emphasizes the safety protection of users. We operate electrical products conveniently and are not harmed by electrical appliances. Assuming that some or all functions of electrical products are lost during use and will not bring danger to users, then we judge that the safety design of the product is qualified.
3. Need to meet national standards
The electrical equipment produced and sold in my country needs to meet the requirements of the safety testing regulations marked in the GB standard, and the safety testing is mandatory in the general safety requirements of household electrical appliances in my country.
4. Common safety test content
The safety test items mainly include: AC withstand voltage, DC withstand voltage, insulation resistance, grounding resistance, leakage current, load power, low-voltage start-up, open-short test and other eight test items. Today we will focus on the following four core test items:
1. Withstand voltage test: The withstand voltage test is one of the most common safety tests. It essentially refers to applying high voltage at the same frequency (generally, the AC withstand voltage does not exceed 5000V) between the power terminal of the product under test and the exposed metal conductor. , DC withstand voltage does not exceed 6000V), to test whether there is insulation breakdown in electrical products.
Purpose of the test: To confirm whether the voltage of electrical products or parts has sufficient insulation (also called destructive test).
2. Insulation resistance test: Insulation resistance value is the most basic insulation index of electrical circuit. By measuring the insulation resistance value of electrical equipment, it can reflect the insulation condition of the equipment. Apply a DC voltage (generally 500V or 2500V) between the power terminal of the product under test and the bare metal conductor (safety ground) and measure its insulation resistance value to judge whether the electrical appliance is partially or overall damp and dirty , and defects such as insulation breakdown and severe overheating aging.
Purpose of the test: To continue to confirm the insulation performance test.
3. Leakage current test: Leakage current is the main index to measure product safety performance. During the test, connect a human body simulation impedance (MD) between the power supply of the product under test and the bare metal conductor (safety ground), and test whether the leakage current flowing from the power supply through MD to the ground exceeds the standard. Generally speaking, leakage current control The smaller the value, the higher the safety performance of the product.
Purpose of the test: To detect whether the leakage current of the easily-touched metal or plastic casing of the electrical appliance may cause personal electric shock to the user when it is working under the specified conditions.
4. Grounding protection test: When the product fails due to basic insulation, in order to ensure that the grounding can effectively lead the dangerous voltage to the earth, we also need to conduct a grounding test on the electrical appliances. Apply a constant current power supply between the grounding protection terminal and the bare metal conductor to test the continuity of the grounding loop and the conduction resistance or conduction voltage drop does not exceed the standard value, so as to confirm that the accessible metal parts have the ability to dissipate dangerous voltage Lead to the earth, so as not to cause harm to the human body.
Test purpose: to confirm whether the grounding is accurate when the resistance is low.
Generally speaking, qualified products can be sold in the market only after the above-mentioned test requirements are met. The safety test requirements represent the requirements of safety regulations and are a procedure in the national standard certification. All manufacturers should test the products in strict accordance with the safety test specifications before leaving the factory, and assume the heavy responsibility of product safety.