FAQs about Modular UPS 1.0

Time of issue:2021-03-19



1. Is the modular UPS reliable?

Most of the UPS failures occur in the power conversion part (rectifier and inverter circuit). From the perspective of the design concept of modular UPS, because of the use of power module redundancy technology, the reliability of the power conversion part is significantly improved. Other parts such as bypass, input and output power distribution, monitoring and other parts have simple circuit structures and fewer components. , Its reliability is high. Therefore, the overall availability of modular UPS is higher than that of tower UPS.

2. How about the current sharing capability of modular UPS?

There is no essential difference between the current sharing of the modular UPS and the current sharing of other forms of UPS, and the performance indicators must comply with international standards and industry standards or specifications. Refer to the UPS industry standard YDT-2165 of the Ministry of Posts and Telecommunications, when the output power is greater than 4kVA, the system full-load output uneven current is less than or equal to 5%, and when the output power is less than 4kVA, the system full-load output uneven current is less than or equal to 10%.

3. Is the reliability of modular UPS the same as tower UPS?

Many users regard modular UPS as a simple parallel operation of traditional towers, but the difference in working principle between the two is often overlooked. For example, if one UPS in a parallel system is damaged, other UPSs can still work. Many people think that it is the same as a modular UPS. But in fact, after one UPS in the parallel system fails (switched to bypass mode), in order to avoid short circuit caused by the difference in the output of different UPSs (the rated voltage is output in the normal mode, and the mains voltage is output in the bypass mode), the system will all The parallel UPS is switched to bypass mode as a whole. At this time, there is a risk of power failure in the direct supply of utility power. The modular UPS does not have this risk-a power module will automatically exit the system after failure, and the remaining power modules in the system can still work normally. Therefore, the use of modular UPS is safer.

4. Is the modular UPS reliable without the isolation transformer?

Because of the limitations of the circuit topology and early power devices, the traditional industrial frequency UPS needs a built-in transformer at the output to boost the voltage in order to reach the operating voltage required by the load. At the same time, the output transformer can also buffer the impact of the load on the UPS to a certain extent. It is equivalent to an isolation transformer that forms an extra layer of isolation to the system. In today's modular UPS, the power modules are generally equipped with fuses in the input/output, and the output also has relay isolation, which can play the same role as the isolation transformer of the industrial frequency machine. At the same time, once the power module fails, the DSP can react quickly to isolate the faulty module from the system. Therefore, the modular UPS will not reduce the reliability of the system because of the lack of an isolation transformer. On the contrary, the isolation transformers of traditional industrial frequency machines are increasingly difficult to adapt to the needs of new data centers such as high-density, high-efficiency and flexible installation due to factors such as large size and heavy weight. At the same time, the loss of the transformer itself will also generate a lot of heat while reducing the efficiency of the system, shortening the life of the internal components of the UPS.


At present, major UPS manufacturers promote high-frequency UPS products without output isolation transformers as their main products. Except for some special scenarios, there are fewer and fewer scenarios requiring isolation transformers.

5. Does the modular UPS bypass module need to support hot swap?

From the reliability analysis results, in the modular UPS system, the bypass module is the key point that restricts the reliability of the system, because the centralized bypass design has no redundancy (the decentralized bypass has high reliability, but there is a risk of overload) Therefore, the bypass module also needs to support hot swapping.

6. Will the high power density of modular UPS affect the heat dissipation of the UPS?

Modular UPS generally undergoes rigorous thermal simulation analysis during design. At the same time, a large number of experiments will be conducted in the research and development phase to test the temperature of various parts of the machine to ensure that the internal components of the UPS are evenly heated. The power module generally has a fan for forced air cooling to ensure that the internal heat of the product can be dissipated in time. A better product will also have designs such as fan intelligent speed regulation and fan redundancy to improve the overall reliability of the fan and UPS. In addition, you can view the operating temperature range of the UPS, and generally good products can work at higher ambient temperatures.