How to choose the safety standard of computer power

Power is the heart of the computer, the power of bad quality will not only damage the motherboard, hard drives and other components, but also shorten the normal life of the computer. Of course, a good quality of the price of the power supply will not be cheap, so some businesses tend to use cheap power to deceive consumers, and some users do not know this very well, but the difference of dozens of yuan may incur thousands of losses, it is really not worth, so in the purchase should pay special attention to the quality of the power supply is good.

Safety standards to protect the user's life and property security as the starting point, in the raw materials insulation, fire-retardant and other aspects made strict regulations. Meet the safety standards of products, not only the product itself in line with safety standards, but also for manufacturers have a better production safety system. Among these standards, the VDE-0806 standards set by Germany based on 1ec-380 standards are most stringent. The national standard of our country is gb4943-1995 "information technology equipment (including electrical equipment) safety". The power supply meets the above standards and its safety is guaranteed. The power supply conforms to the safety standard of a certain country and obtains the certificate issued by its statutory department, such as obtaining the certificate issued by the UL institution, which is called the UL certification. China's security certification body is CCEE. No matter which country's security certification, all of the creepage distance, resistance to electrical strength, leakage current, temperature and other aspects made strict regulations.

Requirements for creepage distances

Creepage distance refers to the shortest distance between two conductive devices measured along the insulating surface or between the conductive device and the device interface. UL, CSA and VDE safety standards emphasize the safety requirements of creepage distance, this is to prevent devices or between devices and between the fire thereby threatening personal safety.

Requirements for resistance to electrical strength

When the AC input line or between the AC input and the chassis from 0 voltage to the AC 1500V or DC 2200V, no breakdown or pull arc is qualified.

Requirements for leakage current

Both UL and CSA require that the exposed, not charged metal parts should be connected with the Earth. The leakage current is measured by using a 1500-euro resistor between these parts and the earth to measure its leakage current. Switching power supply leakage current, in the 260V AC input, should not exceed 3.5mA.

Requirements for temperature

The safety standard attaches great importance to the temperature requirement of the electrical apparatus, and it requires the flame retardant material. For switching power supply, the internal temperature rise should not exceed 65 ℃, if the ambient temperature is 25 ℃, the power supply components of the temperature should be less than 90 ℃. A power supply that does not meet the safety standard has no direct adverse effect on the user when it is first started. However, after a long time, due to humid air and dust impact may lead to high-voltage zone short-circuit, not only caused the power itself damage, but also seriously affect the grid, which adversely affect other electrical appliances.

On electromagnetic interference, the international standard has fcc-a (industrial standard), Fcc-b (Civil standard), the power should meet civil standards. Switching power supply is the frequency of AC rectifier to DC, and then through the switch into high-frequency communication, and then rectifier for a stable DC power supply, so that the power frequency of the rectifier waveform distortion generated by the noise and switch waveform generated noise, in the input side leakage out on the performance of conduction noise and radiation noise, Leaking out on the output side is reflected in the ripple.

Electromagnetic interference is divided into conduction interference and radiation interference. The conduction interference spreads through the power line, the frequency is below 30MHz, mainly interferes the audio frequency band. Because the computer uses the switch power supply has the metal shell to shield, therefore mainly is the conduction interference. The size of the conduction interference is an important standard to measure the power quality of the computer, which includes two aspects: first, to prevent electromagnetic interference in the power grid from the electromagnetic interference generated by the electricity source into the grid, affecting the normal work of the host system; the other is to prevent the electromagnetic interference from the host itself from entering We may have such experience in the daily work, when the computer boot, its nearby electrical appliances such as television, stereo, etc. can not be used normally, this is the impact of conduction interference.

Power classification

At power supply-power generally 150w~220w, a total of four output (soil 5V, soil 12V), another to the motherboard to provide a P.G. Signal. The output line is two six-core sockets and several four-pin plugs, and two six-core sockets provide power to the motherboard. The at power supply is powered off by disconnecting the AC grid. Before the ATX power supply was present, from 286 to 586 computers were unified from the at power supply. With the popularity of ATX power supplies, at power is now gradually fading out of the market.

ATX Power Supply-in Tel l997 February launched the ATX 2.01 standard. Compared with the at power supply, its overall size has not changed, mainly increased +3.3v and +5v standby two outputs and a PS---on signal, the output line to a 20-core line to power the motherboard.

With the increasing CPU working frequency, in order to reduce the CPU power consumption to reduce calorific value, it is necessary to reduce the operating voltage of the chip, so it is necessary to provide 3.3V output voltage directly from the power supply. +5V Standby is also called Auxiliary +5v, which has voltage output as long as it plugs into 220V alternating current. PS---on signal is the motherboard to the power supply level signal, low electricity peacetime power supply start, high electricity peacetime power off. Using +5v SB and ps--on signal, it can realize the function of software switch machine, keyboard boot, network wake and so on. Auxiliary 5V is always working, some ATX power supply in the output socket under the addition of a switch, can cut off AC power input, complete shutdown.

Micro ATX Power-Micro ATX is Intel's standard after the ATX power supply, with the main purpose of reducing costs. The notable change with ATX is the decrease in volume and power. The volume of ATX is 150mmx140mmx86mm,micro ATX volume is 125mmx100mmx63.51mm; The ATX power is around 220W, and the Micro ATX Power is 90w~145w.