Correctly Understand the Safety Testing System Like Withstand Voltage Tester and Electrical Safety Tester

What is safety testing?
The safety series tester is a special measuring instrument for a series of safety performance tests with Electrical Safety Tester by simulating the customer’s possible use of electrical products. For example, it is used to detect whether electrical products are leaking, whether they are well grounded, and whether they will harm personal safety.

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 use withstand voltage tester to judge that the safety design of the product is qualified.

Need to meet national standards
The electrical equipment produced and sold in our country needs to be tested by electrical safety tester 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 our country.

Automatic Safety Test System LS9955 AL3

Common safety test content
The electrical safety tester mainly testing items 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 tester: The withstand voltage test is one of the most common safety tests. A high voltage of several thousand volts (AC or DC) is applied between the shell of the electrical appliance under test or the parts that are easily accessible to the human body and the power supply terminal. , to detect how much leakage current there is under this high voltage, and when the leakage current exceeds a certain value, it may cause personal injury. The essence is to apply a high voltage of the same frequency (generally, the AC withstand voltage does not exceed 5000V and the DC withstand voltage exceeds 6000V) between the power terminal of the product under test and the exposed metal conductor to test whether the electrical product has insulation breakdown.

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 circuits, and the insulation condition of the equipment can be reflected by measuring the insulation resistance value of electrical equipment. Apply a DC voltage (generally 500V or 2500V) between the power terminal of the product under test and the exposed metal conductor (safety ground) and measure its insulation resistance value, and use the 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: In order to continue to confirm the insulation performance test by withstand voltage tester.

3. Leakage current test: Leakage current is the main index to measure product safety performance. During the test, connect a human body simulation impedance Q(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, the leakage current the smaller the controlled 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 will cause personal electric shock to the user when it is working under the specified conditions.
Leakage current detection: divided into dynamic leakage and static leakage by withstand voltage tester .

(1) Static leakage: Apply a voltage 1.06 times the rated working voltage between the shell of the electrical appliance under test and the parts that are easily accessible to the human body and the live wire and neutral wire terminals of the power supply, and detect the maximum leakage current. At this time, the electrical appliance under test does not work . 1.06 times the applied voltage should be provided through an isolation transformer.
(2) Dynamic leakage: while the electrical appliance under test is powered and running, the same detection as static leakage (also called thermal leakage) is carried out.
(3) When selecting a leakage current detection instrument, the input impedance of the leakage current and the capacity of the isolation transformer should be selected emphatically. The input impedance of the tester is required to simulate the impedance network of the human body. Different electrical product standards have different human body network models, which should be selected correctly. The corresponding national standards include GB9706, GB3883, GB12113, GB8898, GB4943, GB4906, and GB4706. The capacity of the output isolation transformer of the withstand voltage tester should be suitable for the capacity of the measured capacitor. When the electrical appliance under test is a motor, etc., and its starting current is several times larger than the rated current, it should be considered according to the starting current.

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 ground, we also need to conduct a grounding test with electrical safety tester on the electrical appliance. 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.
Purpose of the test: 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 electrical safety tester 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.