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One important choice when choosing an uninterruptible power supply (UPS) to use in B2B applications data centers, telecom towers, industrial plants, or railway power systems is the battery voltage architecture. Both high and low voltage systems (400 V to 800 V DC, and 48 V to 220 V DC, respectively) have their own merits. To maximize your critical power infrastructure, it is vital to understand trade-offs among efficiency, safety and fit with application.
Efficiency Comparison Between High Voltage and Low Voltage UPS Battery Systems
UPS systems run at high voltages have much higher efficiency, especially at high power levels. High voltage architectures have 94–97% round-trip efficiency, versus 88-92% with low voltage systems in large-scale installations, above 100kW. This is mostly due to less current, as higher voltage allows lower current for the same power, which reduces resistive (I2R) losses in cables, connectors, and busbars. High voltage systems are also able to be directly integrated to modern lithium battery racks without any series-parallel conversion losses. Very thick copper busbars are needed to support high currents (e.g. 1,000A+ to support 50kW) in low voltage systems, particularly at 48V, resulting in higher cost of installation and losses. In mission critical facilities where they are operational 24/7 the 5-8% efficiency of high voltage translates into thousands of dollars of saving in yearly electricity.
Safety Considerations for High Voltage UPS Installations in Industrial Environments
UPS systems that use high voltages require strict safety measures. Higher voltages (above 400 V DC) need extra precautions: analysis of arc-flashes, insulated tools, controlled access areas, and special training of maintenance staff. Modern high voltage systems, however, provide battery management systems (BMS) utilizing contactor-based isolation, fuse protection on each string and insulation monitoring devices (IMD) that identify ground faults prior to becoming hazards. Smaller facilities with no dedicated electrical rooms are best equipped with low voltage systems (48V-110V) because they are safer to people working close to exposed terminals. In fact, in industrial settings where the operators are not trained, or where the operators contact the equipment frequently, the risk of electrocution is minimized by low voltage. With that said, high voltage installations in controlled conditions, such as dedicated battery rooms with access control and appropriate PPE are well deployed and have proven safe in thousands of telecom central offices and data centers around the world. This will be determined by the available safety structures and maintenance capacity of your facility.
Which UPS Battery Voltage is Better for Data Centers and Telecom Projects?
In the case of data centers, high voltage UPS systems (400 V -800 V DC) are becoming the norm. They are more efficient at standard data center loads (200kW-2MW), are less expensive in copper busbar, and can be directly integrated with lithium batteries. The high voltage also extends the run time by having fewer parallel strings and it is easy to manage the battery.
For telecom projects, it is a matter of scale. High voltage (240 V to 400 V) is commonly used in central offices having large DC power plants (10kW to 100kW) to meet efficiency objectives. Remote telecom shelters, cell towers and outdoor cabinets are however usually fed with low voltage 48V DC systems, the telecom industry standard over decades. The 48V is less unsafe to field technicians in uncontrolled field, and the ecosystem of 48V rectifiers, batteries and distribution components is well-established and ubiquitous. Most telecom operators operate access networks at 48V, and core network facilities at higher voltages.
Conclusion
Select high voltage UPS in large data centers and central offices where efficiency and space savings are important enough to warrant high-tech safety measures. Use low voltages (48V) in telecom access networks, remote locations and small facilities where technician safety and the maturity of the ecosystem is the most critical consideration. In the hybrid deployments, Shenzhen Weitu Hongda Industrial Co., Ltd. provides tailored UPS and energy storage solutions in both voltage architects, with ISO and CE certification. Get in touch with us to develop the appropriate power protection in your infrastructure.