What are the mains power sources that have a significant impact on UPS power supply?

As a public power grid, the municipal power system is connected to thousands of various loads. Some of the larger inductive, capacitive, and switching power sources obtain electrical energy from the grid, but in turn, they can affect the grid itself, deteriorate the power supply quality of the grid or local grids, and cause waveform distortion or frequency drift of the municipal power voltage. In addition, accidents and man-made incidents such as earthquakes, lightning strikes, power transmission and transformation system circuit breakers or short circuits can all endanger the normal supply of electricity, thereby affecting the normal operation of loads. These issues with the mains power supply can lead to power outages and other problems with the UPS power supply, causing people to mistakenly believe that the UPS power supply is malfunctioning without finding the true cause of the problem.

According to power testing, there are several common issues in the power grid that can interfere with or damage computers, precision instruments, and UPS power supplies, including the following:

1、 Transient overvoltage

Transient overvoltage refers to a pulse voltage with a peak voltage of up to 20000V, but a duration ranging from one millionth of a second to one millionth of a second. The main reason and possible damage it may cause are similar to high-voltage sharp pulses, but there will be differences in the solution.

2、 Voltage sag

Voltage sag 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. Starting large equipment, starting large electric motors, or connecting large power transformers can all cause this problem.

3、 Surge

Surge refers to an effective output voltage that is 110% higher than the rated value and lasts for one or several cycles. Surge is mainly caused by the high voltage generated by the sudden unloading of large electrical equipment connected to the power grid when it shuts down.

4、 Continuous low voltage

Continuous low voltage refers to the effective value of the mains voltage being lower than the rated value and lasting for a long time. The reasons for its occurrence include: startup and application of large equipment, switching of main power lines, startup of large motors, and line overload. If your mains power has similar issues, we suggest that you ask the power department to measure parameters such as frequency, waveform, and voltage of the grid to confirm if the mains power has the above-mentioned problems.

5、 Frequency offset

Frequency offset refers to the variation of the mains frequency exceeding 3Hz. This is mainly caused by the unstable operation of emergency generators or power supply from sources with unstable frequencies.

6、 Wire noise

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

7、 High voltage sharp pulse

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