Introduction: Power is the heart of information systems and electronic products. The quality of AC power determines the normal operation of information systems and electronic products. Therefore, to understand the quality of the AC power supply in order to provide effective solutions. The quality problems of AC power supply are as follows:

1. The range of voltage change is too large, the power supply is insufficient, the power supply department takes a step-down power supply, or is located in a remote area with excessive losses, resulting in a low voltage. The power grid has too little power, resulting in high voltage, low voltage, and low load. The voltage is too high, the service life of the load is shortened, or the load is burned.

2. Waveform Distortion (or Harmonic Waveform Distortion). Common waveform distortion refers to multiple harmonics of a standard power supply waveform. The cause of power grid harmonics is the use of switching power supplies in power electronics and electrical equipment such as rectifiers and UPS power supplies, or secondary power supplies themselves. Harmonic harm to the utility grid mainly includes:

1) Make the components in the utility grid generate additional harmonic losses, reduce the efficiency of power generation and transmission and transformation equipment. When a large number of third harmonics flow through the neutral line, it will cause the line to overheat or even cause fire;

2) Affect the normal operation of various electrical equipment, in addition to causing additional losses, but also make the motor produce mechanical vibration, noise and overvoltage, so that the transformer local severe overheating, so that capacitors, cables and other equipment overheating, insulation aging, shortened life expectancy, Resulting in damage;

3) It will cause partial parallel resonance and series resonance in the utility grid, so as to amplify harmonics, so that the aforementioned hazards are greatly increased, even causing serious accidents;

4) It will lead to relay protection and automatic device malfunction, and make the electrical measuring instrument measurement inaccurate;

5) It will cause interference to neighboring communication systems, light noise will be generated, communication quality will be reduced, and information loss will be caused by serious ones, making the communication system unable to work normally.

3. Surge (or Surge Power Surges) means that the output voltage has an rms value greater than 110% of the nominal value within a few moments and lasts for one or several cycles. It is the main culprit in the destruction of sophisticated electronic equipment. In addition to the lightning strikes, the main reason is that the high voltage generated by the sudden unloading of the power grid when the large electrical equipment connected to the power grid is turned off and on.

1) The impact of surges on sensitive electrical and electronic equipment is the following types:

Destruction: voltage breakdown of semiconductor devices; destruction of components metallized surface; destruction of printed circuit board printed circuit or contact points; destruction of three-terminal dual thyristor components / thyristors ...

Interference: lockout, thyristor or triac loss of control; partial destruction of data files; data processing program errors; errors in receiving and transmitting data and failures; unexplained failures...

Premature aging: premature aging of components and shortened electrical life; output sound quality and picture quality decline.

2) Which electrical equipment will be destroyed by power surge

Electrical equipment containing microprocessors is vulnerable to power surges. This includes computers and auxiliary equipment, program-controlled switches, radio and television transmitters, video equipment, and microwave relay equipment. Products in the home appliance industry include televisions, washing machines, and refrigerators. Wait. The survey data shows that 63% of the electrical equipment that had problems during the warranty period was caused by power surges.

4. Spikes (or spikes spikes) refer to peak voltages up to 6000V and durations from one ten-thousandth of a second to 10ms. This is mainly due to lightning strikes, arcing, static discharges, or switching operations of large electrical equipment.

Its harm is mainly: When the spike amplitude is very large, it will destroy the input power filter, rectifier and even the main vibration tube of the IPC switching power supply. Coupled with its wide spectrum, it can break into the computer and cause interference.

5. Transient overvoltage and temporary overvoltage refer to pulse voltages with peak voltages as high as 20000V, but with durations ranging from one millionth of a second to one ten-thousandth of a second. The main reason and possible damage are similar to high-voltage spikes, which are mainly caused by thunder and lightning.
Its hazards are: Advanced electronic devices such as measurement, monitoring, communications, and computer networks with large-scale integrated circuits as their core components are widely used in various fields of modern life. These electronic devices made up of large-scale CMOS integrated components are widely used. The shortcomings of transient overvoltage and overcurrent withstand capability are weak. Transient overvoltage will not only cause misoperation of electronic equipment, but also cause interference to electronic equipment, data loss, or temporary failure. In severe cases, it can cause breakdown of components. And the circuit board burned down and paralyzed the entire system.

6. Sags & Brownouts (Sags & Brownouts) refer to low voltage conditions where the rms voltage of the mains voltage falls within the range of 80-85% of the nominal value and lasts for one to several cycles or even longer. The reasons for this include the start-up and application of large-scale equipment, the start-up of large-scale motors, or the access of large-scale power transformers, the switching of main power lines, and the overload of lines.

Its hazards are mainly: voltage sags are the most common power problem, and it accounts for 87% of power problems. Its impact on the computer will cause the interface device to suspend operations, and it will cause data loss and file destruction. The voltage sagging also destroys the components inside the computer, which shortens the life.

7. Three-phase voltage imbalance means that the voltages between the phases are not equal or the phase angles are not equal, due to the unbalanced load of the phases.

The standard stipulates that the allowable value of the unbalance under the normal operating mode of the public connection point of the power system is 2%, and the short-term time must not exceed 4%. Harm to the transformer. When the three-phase load is unbalanced, the transformer is in an asymmetrical operating state. Causes the loss of the transformer to increase (including no-load loss and load loss). According to the rules of transformer operation, the neutral current of the transformer during operation shall not exceed 25% of the rated current of the low voltage side of the transformer. In addition, three-phase load unbalanced operation will cause the transformer zero-sequence current is too large, local metal parts heating up, and even lead to transformer burned. Impact on electrical equipment. The occurrence of three-phase voltage imbalance will lead to several times the current imbalance occurs. The reverse torque increase in the induction motor increases the temperature of the motor. Imbalance between the phases will lead to shortened service life of electrical equipment and increase the cost of equipment maintenance. The allowable current of the circuit breaker is reduced, and overload or short circuit is likely to occur when the load is changed or alternated. Unbalanced currents flow into the neutral line, causing the neutral line to thicken. Impact on line loss. The three-phase four-wire connection method minimizes the line loss when the three-phase load is balanced; the line loss increase is small when the one-phase load is heavy and the two-phase load is light; when the three-phase load is unbalanced, no matter what Load distribution, the current is not balanced, the line loss increases.

8. Noise interference refers to radio frequency interference (RFI) and electromagnetic interference (EFI) and other high-frequency interference. Originated from the induction of electromagnetic waves or high-frequency waves, it is a high-frequency change with a potential disturbance of 15-100% at the frequency of 50 Hz of normal power. Motor operation, breaker action, motor controller operation, broadcast launch, microwave radiation, and electrical storm can all cause noise.

The main harms are: excessive noise may cause misjudgment on the computer CPU. In severe cases, CPU and other computer accessories may be burned, which may cause interruption of radio transmission. The induction is conducted to the surrounding environment, resulting in other electronic devices. Failure to work properly. Can make civil aviation system work failure, communication is not smooth, computer operation error, automatic equipment malfunction.

Auschitz's AC parametric power regulator plays an important role in improving the power quality of the distribution network. The device has the following functions:

1) Maintain the load-side voltage constant under conditions of primary-side voltage fluctuation or short-term power interruption of 2-3 cycles.

2) Maintain the three-phase voltage balance on the load side under unbalanced primary voltage and harmonic conditions.

3) Current harmonics and reactive power on the load side can be compensated so that the net side only provides active current.

4) The unbalanced current harmonics on the load side can be compensated to make the grid-side current three-phase balanced.

5) It can eliminate all kinds of micro power interference pollution.