Requirements for the use of UPS uninterruptible power supply

The switching time of the static bypass switch is generally 2-10ms, and it should have the following functions:
a. When the inverter device malfunctions or needs maintenance, it should be promptly switched to the power grid (mains backup) for power supply.
b. When the branch circuit suddenly experiences a fault short circuit and the current exceeds the predetermined value, it should be switched to the grid (city backup) power supply to increase the short-circuit current, so that the protection device can quickly operate. After the fault is cut off, it can be restarted to return to the inverter for power supply.
c. The uninterruptible power supply device with frequency tracking link should automatically disconnect from the grid when the grid frequency is passive or the voltage fluctuates beyond the rated value, and then automatically connect to the grid when the frequency and voltage return to normal.
When using the mains bypass, the frequency and phase of the inverter should be synchronized with the mains lock.
3. For three-phase output with imbalance, the difference between the fundamental root mean square currents of the maximum and minimum phase loads should not exceed 25% of the rated current of the uninterruptible power supply, and the maximum line current should not exceed its rated value
The imbalance coefficient of the detected voltage in the three-phase output system (the sum of the negative sequence component and the positive sequence component) should not exceed 5%. The total waveform distortion of the output voltage should not exceed 5% (10% is allowed for single-phase output)