Common safety regulations and basic requirements for electronic components

Date：2022-04-20 15:00:00Views：973

1、 Basic requirements of safety regulations for electronic components

Generally, when evaluating electronic component products, its safety performance shall be considered from the following aspects:

1. Withstand voltage (electric strength) - prevent electric shock injury

2. Insulation resistance - prevent electric shock injury

3. Grounding resistance - prevent electric shock injury

4. Leakage current - prevent electric shock injury

5. Electromagnetic compatibility - (EMS and EMI)

6. Fire resistance - prevent fire hazard

7. Mechanical structure - prevent damage, burns, etc. caused by mechanical structure defects

8. Energy shock - prevent fire or arc burn caused by high current

9. Other special requirements

2、 Testing requirements for electronic components

1. Withstand voltage test

It mainly considers the bearing capacity of the insulation system under abnormal high voltage. Products with working voltage less than 50V generally do not undergo withstand voltage test. Therefore, class III electrical appliances generally do not need to undergo withstand voltage test. Take American UL certification as an example:

(1) Voltage setting

The withstand voltage is generally related to the rated voltage of the product, and the commonly used calculation formula is:

(1) AC: 1000V + 2 * rated working voltage

(2) DC: (1000V + 2 * rated working voltage) * 1.4

The above is the test voltage for ordinary insulation. If it is double insulation, the test voltage is 2 times the ordinary voltage. If the calculated result is not an integral multiple of 100, take the greater or not

Example: the rated working voltage is 220V, and the test voltage of ordinary insulation is:

AC: 1000 2 * 220 = 1440v, the test voltage should be 1500V instead of rounding

(2) Setting of leakage current

It is generally set at 5 ~ 10mA and the maximum is no more than 100mA. There are different requirements according to different industries. For example, the leakage current of medical devices is generally 1mA

(3) Setting of test time

The general test setting is 1 minute, which can be shortened to 1 second on the production line. When shortening the test time, higher test voltage should be used According to UL regulations, there can be the following relationship conversion:

AC (1000V + 2 * rated working voltage) * 1.2

DC (1000V + 2 * rated working voltage) * 1.4 * 1.2

IEC test parameters are different. For specific parameters, please refer to part X "voltage value of electrical strength withstand voltage test" of this manual.

2. Grounding resistance test

The main consideration is the ability of the product to quickly introduce these charges into the earth in case of insulation collapse or leaked charges under normal working conditions. This is a protective measure, which is not considered in products without grounding.

The smaller the grounding resistance is required, the better. Generally, the single grounding resistance is not allowed to be greater than 0.10 HM, the total grounding resistance of the system is not allowed to be greater than 40 HM, and the continuity resistance between grounding points in the system is not allowed to be greater than 0.01 0hm.

Generally speaking, if the withstand voltage test passes, the insulation resistance test will also pass, but the insulation resistance test passes, but it does not mean that the withstand voltage test will also pass.

In the case of mass production, the production line generally needs to do 100% voltage withstand test. The insulation resistance, leakage current and grounding resistance are only tested during random inspection or when new products are introduced.

3. EMC test

There are many test items required for electromagnetic compatibility, and the general requirements are:

a. Conducted interference and anti-interference

b. Radiation interference and anti-interference

c. Antistatic

d. Lightning resistance

e. Anti surge or voltage mutation, etc

EMC is the abbreviation of electronic compatibility, mainly including (EMS and EMI). Although not all certification bodies have requirements, many countries have listed it as a mandatory project, and independently carry out electromagnetic compatibility certification - EMC certification

EMC includes two requirements: one is that the electromagnetic interference generated by the equipment to the environment during normal operation shall not exceed a certain limit (EMI); On the other hand, it means that the appliance has a certain degree of immunity to the electromagnetic interference in the environment, that is, electromagnetic sensitivity (EMS).

EMI:Electro Magnetic Interf erence

EMS:Electro Magnetic susceptibility

4. Fire resistant and flame retardant

For the combustion evaluation of electronic products, the world mainly adopts the American UL94 combustion test standard, that is, the rubber used must pass the corresponding flame retardant grade test requirements.

The combustion test of plastic and insulating materials is generally evaluated according to UL94. According to the material form of products, they can be divided into three categories, using slightly different test methods.

Colloidal particles: 94hb, 94v-1, 94v-2, 94V-0, 94-5va, 94-5vb

Foam: 94hbf, HF-1, HF-2

PU membrane: 94vtm-0, vtm-1, vtm-2

2、 Product certification of key electronic components

Generally speaking, the following components need safety certificate, and they are also safety critical components. Plastic shell and nameplate;

PCB board and fuse;

Varistor, discharge tube;

Inductance and transformer;

Optocoupler, X capacitance, y capacitance;

Socket and wire;

Silica gel, heat shrinkable pipe, sleeve, PVC sheet;

Fan, relay, switch, temperature switch

Electrical couplers, connectors, etc

Safety regulation parts are the key parts under the control of safety regulation certification bodies. Generally, they need to be certified by relevant countries. There is no way to use them in other products without certification. At the same time, if these safety regulation parts are changed, they must apply to the safety regulation certification authority for filing. They can only be used after obtaining approval. Sometimes they must be re submitted for test. They can be officially used only after passing the test.

Note: for different products and occasions, the provisions of key components are different.