Home News Data Center Facility

UPS S-ECO Mode: An Energy-Saving Revolution for Data Centers

Sept 21, 2022

[Shenzhen, China, September 21, 2022] Data Centers are fundamental for digital Economy. Demand for data center infrastructure has been growing rapidly in the increasingly digitalized world. Given that data centers are energy-intensive facilities, there is pressure to make them more energy-efficient and reduce their environmental impact on the planet.

Power Usage Effectiveness (PUE)is widely accepted as a key metric to determine the overall energy efficiency of a data center. As the PUE depends on multiple factors throughout the data center lifecycle, it is challenging to reduce the PUE even by 0.01.

Uninterruptible Power Supplies (UPS), a battery backup that supplies power and secures uptime of data centers, consumes a large part of the electricity for data center facilities. Thus, a highly-efficient UPS is vital to improving PUE values in the long term.

Many UPS systems have an energy-saving operating mode, known as the ECO mode. The upgraded Super ECO (S-ECO) mode can be used to reduce the PUE of data centers by 0.03–0.04. The S-ECO mode works in different types of power grids and is applicable to mainstream data center architecture. If the S-ECO technology is widely used in data centers, it will trigger an energy conservation revolution.

Balance Between Efficiency and Stability

Each data center is designed to carry the maximum load power, which varies according to the data center scale.

Data Center Scale Designed Max. Load Power P (MVA)
Hyperscale P≥40
Large 40>P≥10
Medium 10>P≥5
Small P<5
Mapping between data center scales and load power


According to the recently-published UPS S-ECO Technology White Paper, when the UPS load rate of a 10 MVA data center is 40%, the PUE can be reduced by about 0.01 each time the efficiency is improved by 1%, and up to 500,000 kWh of electricity can be saved. The UPS S-ECO mode can improve the system efficiency by 3%–4% and reduce the PUE by 0.03–0.04, meaning that 1.5 to 2 million kWh of electricity can be saved each year. If all 10 MVA or larger data centers around the globe use this technology, billions of kWh of electricity will be saved each year.

The S-ECO mode is developed to meet the needs of the industry.

First, going green is a must for the data center industry to achieve healthy and sustainable development. It is an inevitable trend to build a high-density, efficient, and energy-saving power supply system. The S-ECO technology is key to improving the efficiency of the power supply system.

Second, the energy consumption of a traditional power supply system accounts for nearly 10% of the total energy consumption of a data center. It is urgent to improve UPS efficiency through technological upgrades.

A conventional UPS works in online double-conversion mode. It converts utility power through the rectifier and inverter, which then supply high-quality power to loads. This mode features high reliability but low efficiency and high power consumption.

The ECO mode is designed to improve efficiency. In this mode, the UPS supplies power to loads through the static bypass, which is equivalent to a direct supply of utility power. However, the ECO mode has problems of interruption during transfer and harmonic compensation, which compromises the stability of the system.

It is a challenge to keep a balance between efficiency and stability.

Values of the S-ECO Mode

Is there a technology that promises both high efficiency and stability while solving the problems of interruption and harmonic compensation?

The S-ECO mode is such a solution.

S-ECO is an innovative UPS working mode based on the S-ECO technology. It optimizes the power supply architecture and logic and solves the problems of low system efficiency in online double-conversion mode, and output interruption, large harmonics, and input surge voltage interference in ECO mode.

The technology solves the following problems:

First, interruption during transfer. The S-ECO mode enables 0 ms transfer time between any modes. When the UPS works in the S-ECO mode, it automatically detects the power quality of the bypass input. When the bypass input is normal, the bypass supplies power. When the bypass input is abnormal, the UPS transfers to inverter mode with 0 ms time. The dynamic response level of class 1 defined in IEC 62040-3 is met. The UPS automatically transfers back to bypass mode once the bypass recovers.

Second, low efficiency in online mode. The S-ECO mode delivers high efficiency in the full load range. When the bypass supplies power, the UPS power consumption is extremely low, and the system efficiency is greater than 99.1% at its peak or 98.5% when the load rate is above 20%.

Third, input surge voltage interference. The S-ECO mode suppresses high-voltage surges. When the bypass supplies power directly, the surge voltage of the bypass input is easily transmitted to load ports. To address the high surge voltage, the S-ECO mode uses the high and low voltage clamping technology to compensate for voltage when it decreases and absorb voltage when it increases. It has been verified that the output voltage meets IEC 61000-4-5 requirements on surge voltage.

Fourth, large harmonics. The S-ECO mode implements active harmonic compensation. The power supply units in IT equipment provide the power factor correction (PFC) function. When the input power factor (PF) is good (> 0.9), the bypass can supply power directly. However, mechanical and process equipment, such as air conditioners, fans, and water pumps, do not have the PFC function. When the bypass supplies power directly in the traditional ECO mode, reactive power and high-order harmonics are generated and flow into the power grid, which increases the line loss, accelerates  insulation aging, and shortens the equipment service life.

The S-ECO mode has the following features:

First, it is intelligent. 0ms transfer time and active harmonic compensation are powered by intelligent judgment and scheduling.

Second, it is a supplement to the power grid quality. If a data center uses direct utility power supply, the power grid quality problem cannot be avoided. Even a short power outage will cause immeasurable loss. Users can select the online mode or S-ECO mode based on the power grid quality to meet the requirements in any power grid environment.

Third, the technology is adaptive. Alike the online mode, the S-ECO mode applies to diverse power supply architectures. Either the dual-route S-ECO mode or the one-route S-ECO mode plus one-route online mode ensures the efficiency of the power supply system.

A Power Conservation Revolution for Data Centers

Technologies must be verified in actual applications to demonstrate their benefits.

Huawei UPS5000-H flagship models are equipped with the S-ECO mode, and its performance has been fully verified. The models cover the capacity of 400 kVA to 1600 kVA and are applicable to medium- and large-capacity data centers and mission-critical power supplies in various industries.

UPS5000-H-1200 kVA 

TÜV Rheinland and China Telecommunication Technology Labs have performed strict tests on the S-ECO mode, with all its parameters meeting the expectations. The test results show that the UPS5000-H can achieve an efficiency of over 98.5% when it carries 20%–100% loads and deliver an efficiency of over 99.1% at the peak point. As the common load rate of a data center is 20%–80%, the UPS5000-H delivers far higher efficiency than other products of its kind. When the bypass input is abnormal, the UPS transfers to online dual-conversion mode and delivers the efficiency up to 97%. The UPS5000-H is extremely energy-saving. It solves the problems that exist in the traditional ECO mode, such as interruption during transfer, harmonic pollution, and voltage dip and surge voltage on the power grid side.

The S-ECO technology has been used in Huawei Cloud Ulanqab Data Center and other colocation facilities. The S-ECO mode improves the system efficiency by 3%–4% without compromising reliability. Compared with the UPS efficiency of 95%–96% in the industry, the S-ECO mode reduced the PUE by 0.03–0.04. It provides an innovative technology and feasible solution for designing highly reliable and efficient data centers or mission-critical power supply solutions in various industries.

Huawei Cloud Ulanqab Data Center

The S-ECO mode provides 2% higher half-load efficiency and 3% higher full-load efficiency than the online double-conversion mode. Take a case in China as an example. If the electricity fee is CNY0.8/kWh, the 10-year electricity cost of a 10 MVA data center can be reduced by CNY7.784 million, which is equivalent to US$1.1361 million.

If all data centers use UPS products equipped with the S-ECO technology, an enormous amount of electricity fee will be saved each year. Going green is essential to sustainable development as it helps save energy and promote socio-economic evolution.

The S-ECO mode facilitates green transformation and will trigger a power conservation revolution for data centers.

To download the UPS S-ECO Technology White Paper, visit