Several common problems with power supply

The power grid often interferes with or damages computers and precision instruments, mainly in the following aspects:

1. Power surges: refers to the output voltage effective value higher than the rated value by 110%, and the duration is one or several cycles. Power surges are mainly caused by the high voltage generated by the sudden unloading of the power grid when large electrical equipment connected to the power grid is shut down (for example, when the common household air conditioner is shut down) (we all have such personal experience: the time period around 6:00 to 9:00 in the evening is the peak period of electricity consumption, the mains voltage is generally low, and the lights at home are relatively dim. After the peak period of electricity consumption, for example, around 10:00 in the evening, you will find that the lights at home suddenly flash and become much brighter. This is the most common surge phenomenon we see in our daily life).

2. High voltage spikes: refers to a voltage with a peak value of 6000V and a duration from one ten-thousandth of a second to one-half cycle (10ms). This is mainly caused by lightning strikes, arc discharges, static discharges or switching operations of large electrical equipment.

3. Switching transients: refers to a pulse voltage with a peak voltage of up to 20,000V but a duration between one millionth and one ten-thousandth of a second. Its main cause and possible damage are similar to those of high-voltage spike pulses, but there are differences in the solution.

4. Power sags: refers to a low voltage state where the effective value of the mains voltage is between 80% and 85% of the rated value and lasts for one to several cycles. This problem may be caused by starting large equipment, starting large motors, or connecting large power transformers.

5. Electrical line noise: refers to radio frequency interference (RFI), electromagnetic interference (EFI) and other various high-frequency interferences. The operation of motors, the action of relays, the operation of motor controllers, broadcast transmissions, microwave radiation, and electrical storms can all cause line noise interference.

6. Frequency variation: refers to the change of the mains frequency exceeding 3Hz. This is mainly caused by the unstable operation of the emergency generator or the power supply with unstable frequency.

7. Continuous low voltage (brownout): refers to the effective value of the mains voltage being lower than the rated value and lasting for a long time. The causes include: starting and application of large equipment, switching of main power lines, starting of large motors, and line overload (this problem exists in many areas of our country).

8. Power failure: This is the power outage we usually encounter. The causes include: circuit breaker tripping on the line, power supply interruption, and power grid failure.

As humans enter the information society, how to protect computers, networks, and data has become a topic of great concern to people. The design, monitoring, and improvement of power quality is not only a quality issue, but also a safety issue. The application of uninterruptible power supply is not only a backup power supply technology, but also a comprehensive protection of power quality. Improving power quality to meet the normal operation of the information society is a new topic. Generally, simple user solutions can improve the power supply quality of information equipment through AC voltage stabilizers, anti-interference filters, and uninterruptible power supplies. At the same time, it is also necessary to consider reducing the pollution of information equipment to the power grid, improving the power factor, reducing the current harmonic component, and suppressing the conducted radiation interference within a certain range.