What is an uninterruptible power supply? Why do we need it? How do we choose?
In today's era of comprehensive informatization, enterprises have increasingly high requirements for the stability of electricity. A brief power outage may cause system interruption or data loss, and reliable backup power has become crucial for enterprise operations. In recent years, uninterruptible power supplies have once again received attention, but there are numerous models and large differences in specifications on the market, ranging from tower and rack mounted to different power and backup times, often leaving companies unsure how to start, and may even not understand what UPS is. This article starts from the principle of UPS, deeply analyzes the operational architecture and selection points of UPS, and assists enterprises in quickly selecting the truly suitable uninterruptible power supply solution that meets their needs.
UPS (Uninterruptible Power Supply) is a power storage device that can immediately provide electricity in the event of an abnormality or power outage in the main power supply. It forms an energy conversion and storage circuit through internal batteries, rectifiers, and inverters, allowing the equipment to continue operating without interruption in the event of a power outage. For servers and network devices that require high-density computing, having UPS is equivalent to having power backup, achieving a power defense line for continuous stable operation and data security.
- Prevents data loss and system interruption: When the UPS system detects a power anomaly, it can switch to internal battery power within milliseconds, allowing servers and storage devices to continue operating.
- Stabilizes voltage and filters noise: Through rectification and inversion mechanisms, the UPS system outputs a stable current, preventing hardware damage caused by voltage surges and interference.
- Extends equipment lifespan: Reduces the impact of frequent power on/off cycles and surges on electronic components, maintaining long-term stable operation.
- Ensures smooth data backup: When a power outage exceeds the load-bearing time, the UPS system can automatically issue an alert and assist in the safe shutdown of the system, preventing the risk of data corruption or file loss.
The core principle of a UPS is to ensure uninterrupted power supply. Under normal power conditions, the UPS simultaneously regulates and filters the voltage of the equipment (to prevent voltage instability or surges) and charges its internal batteries. However, in the event of a power outage or voltage anomaly, the UPS automatically switches to battery power within milliseconds. The rectifier first converts the AC mains power (DC) to AC, and the inverter then converts the DC back to AC. This is called double conversion, which results in a cleaner, less noisy output sine wave. Through this power conversion process, the UPS can smoothly take over in the instant of a mains power outage, avoiding the risk of data loss or equipment restart.
Online UPS, also known as dual conversion UPS, has the highest protection level among the three types. It operates simultaneously with power facilities. After the mains power enters, it will first be rectified and converted into DC power, and then the inverter will output clean and stable AC power to the equipment for use. When the mains power is interrupted, the UPS will immediately switch to internal battery power supply. Due to the continuous voltage stabilization and filtering, there is no conversion delay in the entire process, and the system can continue to operate without interruption.
This type of UPS can effectively filter out power noise and surges, providing the cleanest voltage quality. However, due to its complex structure and large size, the construction cost is also high, and it is usually used in environments such as telecommunications rooms, medical equipment, or large data centers that require extremely high power quality.
Offline UPS, also known as backup UPS, is usually in standby mode and only starts internal battery power supply when there is a power outage or abnormal voltage. Due to the need for a switch during the switching process, there will be a very short delay time, resulting in relatively low protection. It has a simple structural design, small size, light weight, and low cost, suitable for general household computers, office equipment, or consumer electronics products, and does not require a highly stable power supply application environment.
Online interactive UPS operates between online and offline modes. When the mains power is normal, the power will be directly output to the equipment through the transformer, and the inverter will act as a battery charger. Once an abnormal mains voltage or power outage is detected, the UPS will immediately switch to battery power supply. The inverter will convert the direct current (DC) in the battery into alternating current (AC) and output it to the load end. The overall conversion process is faster than offline and will not affect the operation of the equipment.
Compared to online systems that continuously perform dual conversion, it has lower energy consumption and more cost-effective, making it widely used in small and medium-sized enterprise server hosts, network cabinets, communication equipment, and other fields with moderate demand for power stability.
When choosing a UPS uninterruptible power supply system, in addition to considering the UPS type, it is also important to understand its power specifications, battery efficiency, and certified safety. Different models of UPS have differences in power capacity, backup time, and other aspects. It is recommended to evaluate the actual UPS usage needs based on the following four key points before purchasing.
When selecting a UPS, it is important to first know the required capacity of the UPS. If the UPS capacity is too large, it will waste costs; If it is too small, it may cause power failure or automatic shutdown due to overload.
UPS capacity is usually expressed in kVA (kilovolt ampere) or kW (kilowatt). It is recommended to reserve about 20% to 30% expansion space based on the total power consumption of servers or network equipment as a safety buffer to prevent battery aging or expansion.
In addition, because the actual output power of UPS is about 80%, which means 10kVA is only equivalent to 8kW (power factor 0.8). Based on this calculation, if the total power consumption is 15 kW:
Reserved safety factor → 15 * 1.25=19kW
Convert UPS capacity → 19 ÷ 0.8=approximately 24kVA
Therefore, it is recommended to choose a UPS with a capacity of 24kVA or higher to ensure stable operation.
The backup time of UPS depends on the battery capacity and load ratio. Short term backup (5-15 minutes) can ensure a safe shutdown of the system, while long-term backup (over 30 minutes) can support continuous operation. The calculation formula for backup time is as follows:
Backup minutes=Battery capacity x Battery voltage x UPS efficiency ÷ Load wattage x 60
If the battery capacity is larger, the load wattage is lower, and the UPS efficiency is higher (such as online interactive), the backup time will be relatively longer.
In addition, battery type is also one of the key factors in selecting UPS. At present, the usage rate of lead-acid batteries accounts for about 63% of the market, and the usage rate of lithium batteries accounts for about 27% of the market. Lead acid batteries are inexpensive and easy to maintain, suitable for general computer rooms and small and medium-sized enterprises, but they have a large volume and a lifespan of about 3-5 years; Lithium batteries have excellent charging and discharging efficiency, with a lifespan of up to 8-10 years. Although the initial purchase cost is relatively high, they are also a good choice for long-term use.
UPS needs to match the voltage, phase number, and output frequency of the on-site power supply. The common input voltage in Taiwan is 110V or 220V, while large data centers or industrial equipment often use three-phase power. Therefore, when making a purchase, it is important to confirm the voltage of the UPS, whether it supports single-phase or three-phase power, and the output frequency. Some advanced models have automatic voltage stabilization and support for multiple phases. If there is a need, companies can also choose according to their own needs.
After all, UPS is the first line of defense in the power system, so it is recommended to check whether it has international level safety and quality when selecting. Common standards include IEC (International Electrotechnical Commission), UL (United States Safety Standards), and CE (European Union Certification), which can be used to observe whether UPS systems meet safety standards in terms of electrical safety, heat resistance, fire resistance, and electromagnetic compatibility (EMC).
The installation methods of UPS are mainly divided into rack mount and tower, which have differences in volume design, installation flexibility, and applicable fields. Generally, when choosing, the following two points are usually given priority consideration:
Rack mounted UPS is a UPS designed specifically for computer rooms and server cabinets. It can be horizontally installed in a standard 19 inch rack, with high integration and neat line management, making it suitable for IT environments that require centralized management. The characteristics of rack mounted UPS are flat volume, stackable multiple layers, and often configured together with switches, storage devices, etc. inside the cabinet, which can effectively save ground space and perform modular maintenance. The 1U rack mounted unit is 44.45mm. When installing, attention should be paid to the height limit of the cabinet. In the case of small cabinets and wall mounted cabinets, special attention should be paid to whether the UPS depth is suitable for installation in the cabinet smoothly.
Tower type UPS adopts an upright design, resembling a computer host in appearance, and can be placed independently without the need for a cabinet, making installation more flexible than a cabinet. Suitable for placement in general offices, retail counters, laboratories, and other environments, not limited by rack size. If the space is spacious and the equipment is scattered, tower UPS will be a simpler choice.
If the equipment has already been centralized in the server cabinet and monitoring and centralized power management are required, rack mounted UPS will be the only option. Usually, this type of UPS supports hot swapping and can be effectively monitored with an overall data center management system. The new rack mounted UPS is often paired with an efficient lithium battery system, which has higher discharge efficiency and lifespan, especially suitable for data centers or cloud service rooms. Tower UPS, on the other hand, has more flexible installation space, better heat dissipation effect, and more importantly, is more affordable, suitable for environments with spacious space and installation margins.
The UPS market continues to grow, reaching $8.63 billion by 2025 according to Research Nester, with a projected growth rate of 8%. The annual growth rate is influenced by high-density computing and edge data center construction, making lithium-ion UPS, modular architecture, and high power density designs the mainstream trends. The following is an overview of the development trends of internationally renowned UPS manufacturers and Chinese UPS manufacturers:
The global UPS market is mainly dominated by a few large enterprises. Their main models utilize lithium-ion battery designs, reducing size and weight by nearly half compared to traditional lead-acid models, providing higher power density and fast charging capabilities, making them particularly suitable for MicroData Center and edge computing deployments. On the other hand, major global manufacturers also emphasize cloud monitoring, energy efficiency, and scalable modular designs to support the long-term expansion needs of enterprise users in the UPS field. The development of major international manufacturers clearly demonstrates that the competitive focus of international brands has shifted from simple backup functions to intelligent, energy-efficient, and cloud-monitored modular management – a current trend in the UPS market.
The Chinese UPS market has become an international focus. Besides international brands establishing branches in mainland China, local manufacturers are also demonstrating strong competitiveness in the small and medium power UPS sector. Some local UPS manufacturers have long been deeply involved in domestic enterprise and industrial applications, offering a diverse range of products including single-phase and three-phase online UPS and modular rack-mount UPS. They integrate energy management platforms to achieve intelligent power management using AI monitoring and IoT communication protocols.
In addition, some local UPS manufacturers also focus on the domestic and international SME and system integration markets, providing more flexible rack-mount UPS and lithium-ion battery versions with software support advantages. Through local R&D in Taiwan and global OEM manufacturing, they continuously optimize power density and energy conversion efficiency, making them more flexible and competitive than international manufacturers in terms of cost control and service timeliness.
This shows that the development of China's UPS market is also transforming from a traditional hardware-oriented approach to a new stage of integrating intelligent power management and local services.
As enterprise AI computing demands continue to rise, data loss and system downtime caused by power outages will be a critical challenge for future operations. Especially in data centers, server rooms, and critical IT environments, traditional UPS systems, which only provide short-term backup but lack voltage stabilization, energy efficiency, and remote monitoring capabilities, will struggle to meet the requirements of modern infrastructure. TAFENG's professional online UPS uninterruptible power supply system is designed to address these pain points. Its double-conversion online architecture and high-output design with a power factor of 1.0 ensure zero-transfer time for power switching and provide clean and stable power quality. The rack-mount and freestanding designs support intelligent battery management, programmable socket control, and multiple communication interfaces, allowing administrators to monitor equipment status and energy consumption data at any time through ViewPower. Combined with TAFENG's rack-mount server cabinets and power distribution solutions, it creates a modular power management environment. Use TAFENG's professional online UPS solutions to build the highest level of power protection and energy efficiency for your enterprise data center and network/server systems.
