A brief discussion on some UPS indicators or functions that mislead users (Part 2)

UPS efficiency refers to the ratio of the UPS's output active power to its input active power. In fact, it refers to the UPS's own energy loss. For example, the UPS generates heat, which is energy loss, and the fan dissipates heat, which is also energy loss. Because UPS is a power conversion device, it has two levels of conversion inside, AC to DC (rectifier conversion) and DC to AC (inverter conversion). It is impossible to achieve 100% energy conversion in these two levels of conversion, and both have energy loss.

The credibility of UPS with an efficiency of 96% or higher is questionable. If the efficiency reaches 96%, the inverter efficiency and rectification efficiency of the UPS must reach about 98% (0.98*0.98≈0.96) respectively. As far as the current UPS technology is concerned, I am afraid that no manufacturer can achieve this.

In actual use, the real energy saving should focus on the efficiency at low load. Because the load rate of many UPS is generally around 50%, and some are even lower, and high efficiency at this time can really save us electricity bills. The efficiency of many UPS is relatively low at low load, while Delta HIFT UPS can reach almost the efficiency of full load at 30% load.

In addition, UPS has another efficiency indicator: the efficiency of the economic mode (ECO). In the economic mode, when the mains power is relatively normal, the UPS directly supplies power to the load through the bypass, and the inverter does not output. When the mains power is interrupted or abnormal, the UPS will output the inverter, and the inverter will work at this time. Therefore, in this mode, it is equivalent to direct mains power output, so the efficiency is higher. In this mode, the efficiency of Delta HIFT UPS can also reach more than 98%.

6. Module sleep wake-up function problem

Module sleep technology is a feature mainly proposed by telecommunications operators. Because many UPS mentioned above have low efficiency at low load, all operators hope to shut down a certain number of modules at low load to allow the UPS to reach a higher load, thereby improving the efficiency of the UPS.

For HIFT UPS, its efficiency at low load can reach almost the efficiency at full load. In addition, there are some problems with the sleep function: one is whether it can be woken up in time after sleep. If it cannot be woken up in time, overload protection may occur. The second is whether it can be put into load immediately after waking up. This usually takes a while. In addition, can module sleep save energy? What is sleep? Is it closed or not? Closing means that it cannot be put into work in time; if it is not closed, what is its energy consumption?

VII. Problems with built-in synchronous control technology

Synchronous control is a function provided for dual-bus power supply systems. When dual-bus power supply is used, the output of the two buses needs to be phase synchronized in some cases. Some manufacturers' solutions require customers to purchase an external synchronous controller, but Delta HIFT UPS comes with this function built in as standard, so there is no need to purchase it. In addition, the built-in function of the UPS also avoids the single point failure problem of the external hardware synchronous controller.

8. Shared battery pack issues

Battery pack sharing means that multiple modules or multiple racks share one or more battery packs . The benefit of this is that the battery pack utilization rate is greatly improved. Because we found that when a UPS module or rack fails, its own battery pack cannot be used due to the UPS failure (even if the battery is normal), so the entire backup time will be shortened. This problem does not exist when using battery pack sharing.