Client: A large data center from a mobile operator

Condition: The power distribution system of the data center, especially in the server room and the network room, contains a lot of UPS, cooling equipment and other power electronic devices such as switching power supplies. These devices create disturbances, voltage variations and undesired harmonics that pollute the network. This harmonic pollution could then interfere with the communication signals in various ways, thus affecting the quality of communication.

Designed power supply: A 10 kV feeding line is connected with a transformer with a capacity of 2000 kVA, voltage ratio 10/0.4 kV. The main loads are the various types of communications and storage devices in the network which are located in the server room and network room.

Main problem: The harmonic voltage, harmonic current and power factor low-voltage side of the transformer are measured. The THDv reaches 5.1%, which exceeds the national rate of 5%. The THDi reaches an astonishing rate of 26% and has an RMS value of 490 A. Thanks to the use of the latest generation of UPS power, the power factor can be as high as 0.82, but still does not meet the national requirement.

Compensation design: Considering the fact that the actual harmonic could have a certain range of fluctuation, the configuration needs to have a certain margin to deal with possible changes. Therefore the proposed MSAF should have a rated current of 530A. The test results also shows that the three-phased system is unbalanced and the zero sequence harmonic current in neutral conductor is too large. The active filter applied should have a star connection with neural line and our MSAF-M-690/560-WO is recommended.