UPS uninterruptible power supply ECO mode, also known as "economy mode", is a special UPS uninterruptible power supply operating mode that provides higher energy efficiency. ECO mode can provide up to 99% efficiency, with a bypass line (original main power supply) supplying power to the load.

A、 What is the ECO mode of UPS uninterruptible power supply:

The ECO mode is very similar to the basic operating mode used in offline UPS uninterruptible power supplies, known as the "standby" or "line interaction" mode. In these traditionally smaller single-phase UPS power supplies, the inverter/rectifier circuit is in an "offline" state, ready to be turned on at any time in case of power failure or detected issues.

Similar to the online UPS uninterruptible power supply operating in energy-saving mode, the bypass path normally supplies power to the load, allowing the original main power supply to supply power to the load, and only engages the inverter in the UPS uninterruptible power supply system when the mains power supply fails. Therefore, in normal energy-saving mode operation, the original mains power is basically exposed to the load.

Unlike the true online mode, the UPS uninterruptible power supply continuously regenerates the output voltage through the inverter. In energy-saving mode, the inverter in the UPS uninterruptible power supply system operates in "standby" mode. In principle, this is a simple modification of the UPS uninterruptible power supply control software. However, the reality is much more complex.

UPS uninterruptible power outage in ECO mode. jpg

B、 The benefits of ECO mode:

The advantage of energy-saving mode is that the efficiency of the bypass path is usually between 98.0% and 99%. This means that when using energy-saving mode, UPS efficiency will increase by 2-5%.

A difference between 2-6% may result in significant savings.

C、 Risks of ECO mode:

Energy saving mode cannot predict the future. It must respond to existing issues and then switch to the inverter. This means that the main power supply issue can reach the critical load through UPS until the following four situations occur:

1. Check for power issues

2. UPS uninterruptible power supply determines whether and how to respond

3. Power on the inverter in the UPS uninterruptible power supply system

4. Activate the static bypass switch

In practice, these events may take 1 to 16 milliseconds, during which critical loads may occur due to power issues.

On circuits supplying power to PDUs equipped with static switches, even a few milliseconds of power outage can cause a change in the state of the switch. This may lead to adverse state changes in the entire power system, including overload and load drop.

D、 What is Active ECO Mode:

In recent years, some UPS uninterruptible power supply systems now offer an operating mode called ActiveECO mode, sometimes also known as AdvancedECO.

Just like in standard ECO mode, the bypass line (main power supply) supplies power to the load. However, with ActiveECO, the inverter always stays on and runs in parallel with the input without actually carrying a load.

This means that in the event of a power failure, the speed of power transmission is much faster, ensuring higher availability than the true economic model. Even if the inverter does not handle the load, it can absorb harmonic currents and provide power filtering in a manner similar to online UPS.

Obviously, supplying power to the inverter continuously in ActiveECO mode does require more energy than in standard ECO mode. The cost of doing so is that the efficiency of active ECO is 0.5-1% lower than that of normal ECO mode. But the efficiency is still much higher than the online UPS mode, so it provides a happy medium.

In the event of a power failure, the inverter takes over much faster in active ECO mode, which means it provides higher availability than standard ECO mode.

Obviously, the operating efficiency when using ActiveECO is slightly lower than when using pure ECO (about 1%), but this is still much better than online, thus providing users with some enjoyable media.

E、 When to use ECO or active ECO mode:

Key mission sites such as data centers are unwilling to use these energy-saving operating modes because the trade-off between resilience and power quality has deterred operators.

Although it may not be practical to keep the UPS uninterruptible power supply running in energy-saving mode at all times, it is feasible to use the UPS uninterruptible power supply energy-saving mode when the most critical loads are inactive (such as overnight or non working hours).

The parallel UPS uninterruptible power supply system also provides an opportunity. In such an example, a UPS uninterruptible power supply will operate as the "master station" in online mode, while the remaining units will operate in ECO mode until the condition of the main power supply changes and they need to actively support the load.

F、 Should ECO mode be used:

Therefore, it is useful to consider the efficiency of UPS uninterruptible power supply based on the raw input power required to operate the UPS uninterruptible power supply. For example, an old style uninterruptible power supply with a rated efficiency of 94% will transfer 94% of the original input power to the load and connected system, while the remaining 6% will be 'wasted' when running the UPS uninterruptible power supply, typically in the form of heat dissipation. These additional heat sources usually also need to be processed, further increasing the cooling cost of the facility.

In summary, it is understandable that most data centers and other critical mission sites are unwilling to operate their UPS uninterruptible power supply systems in energy-saving mode because the trade-off between resilience and power quality is not worth the potential energy savings. On the contrary, they prefer to choose more modern devices that have higher energy efficiency when operating in the most protective continuous online mode. Operators are more inclined to operate in energy-saving mode only when the mains power supply is relatively stable, the load generates low harmonics (therefore insensitive to mains interference), and the supported equipment can easily handle partial interruptions.