Uninterruptible Power Supply (UPS)

In today's digital age, the stability of power supply plays a very important role in the normal operation of various devices and systems. As a key device to ensure the continuous and stable power supply, the uninterruptible power supply (UPS) has gradually become well-known. However, how to choose has become a confusing issue. Before choosing a UPS, you need to understand its functions and the characteristics and applications of different types.

1. The basic principle of uninterruptible power supply (UPS):

A. Rectification and charging: UPS will first rectify the mains power and convert AC power into DC power. In this process, on the one hand, DC power is supplied to the internal battery pack for charging, so that the battery can store energy for use when the mains power is interrupted; on the other hand, a stable DC power supply is provided for the subsequent inverter link. For example, when the mains power is connected normally, the rectifier is like an "energy conversion station", which efficiently completes the conversion from AC to DC power and reasonably distributes power to the battery and subsequent circuits.

B. Inverter output: When the mains power fails and the power goes out, the UPS will quickly start the inverter. The function of the inverter is to convert the DC power stored in the battery pack back into AC power to continuously power the connected equipment. This conversion process needs to be completed in a very short time to ensure that the equipment will not shut down or be damaged due to power outages. For example, if the computer suddenly loses power during use, the UPS can output AC power through the inverter, allowing the computer to continue to run for a period of time, so that the user has enough time to save data and shut down normally.

2. Types of Uninterruptible Power Supply (UPS):

A. Online UPS: This type of UPS always allows the device to be powered by the inverter, and the mains power is only used to charge the battery and serve as a backup power supply when the inverter fails. Its advantages are that it can provide high-quality and stable power output, and has a good suppression effect on voltage fluctuations, frequency drifts, harmonic interference, etc., which is very suitable for precision instruments, servers and other equipment with extremely high requirements for power quality. For example, in the server of the data center, once there is a problem with the power supply, even extremely small fluctuations may cause data loss or system failure, and the online UPS can perfectly cope with it.

B. Backup UPS: When the mains power is normal, the mains power directly powers the device and charges the battery at the same time. When the mains power is interrupted, it switches to battery power and outputs AC power through the inverter. The backup UPS has a relatively simple structure and low cost. It is suitable for some devices that have a short tolerance for power interruptions and do not have particularly high requirements for power quality, such as ordinary home computers and small office equipment. When there is an occasional power outage at home, the backup UPS can provide power to the computer for several minutes to more than ten minutes to prevent the loss of the document being edited.

C. Online interactive UPS: It combines some characteristics of online and backup UPS. When the mains power is normal, the inverter stabilizes and filters the mains power to power the device and charge the battery at the same time; when the mains power is abnormal, it switches to battery inverter power supply. This UPS achieves a certain balance between power quality and cost, and is suitable for some commercial places or small network devices that have certain requirements for power quality but limited budgets.

3. Key parameters of uninterruptible power supply (UPS):

A. Capacity (VA): Capacity indicates the maximum apparent power that the UPS can provide. Generally speaking, it is necessary to select a UPS of appropriate capacity based on the total power of the connected equipment. For example, if there is a 500W computer, a 300W printer, and some network devices with a total power of 200W, then the total load is about 1000W, and you need to choose a UPS with a capacity greater than 1000VA. It is usually recommended to reserve 20%-30% margin to cope with the instantaneous power demand when the equipment starts.

B. Battery life: This depends on the capacity of the battery and the size of the load. The larger the battery capacity and the smaller the load, the longer the battery life. For example, a UPS equipped with a battery capacity of 100Ah may have a battery life of about 30 minutes when the load is 500W; when the load increases to 1000W, the battery life may only be about 15 minutes. In some critical application scenarios, such as medical equipment in hospital operating rooms, a longer battery life is required to ensure that the equipment can continue to operate during a mains failure and ensure the safety of surgery.

C. Conversion time: For online UPS, the conversion time is almost zero, because the equipment is always powered by the inverter; while backup UPS and online interactive UPS have a certain conversion time, generally between a few milliseconds and more than ten milliseconds. Although this time is very short, it may still have an impact on some equipment that is extremely sensitive to power outages, such as some industrial automation control systems, so the tolerance of the equipment to the conversion time needs to be considered when choosing.

4. Application scenarios of uninterruptible power supply (UPS):

A. Data center: Data centers store a large number of servers, storage devices, etc. These devices need to operate 24 hours a day and have extremely high requirements for power quality. Uninterruptible power supply (UPS) can provide stable power for data centers when the mains fails, prevent serious consequences such as data loss and system crashes, and ensure business continuity of data centers.

B. Medical industry: Medical equipment in hospitals, such as life monitors and surgical equipment, is related to the life safety of patients. UPS can ensure the normal operation of these devices when the mains power is outage, avoid the impact of power outages on the diagnosis and treatment of patients, and provide reliable power support for medical work.

C. Financial industry: The trading systems, servers and other equipment of financial institutions such as banks and stock exchanges require a continuous and stable power supply to ensure the normal operation of financial transactions. Uninterruptible power supply (UPS) can maintain the operation of financial systems when the city power fluctuates or power outages, prevent transaction interruptions, data errors, etc., and ensure the smooth development of financial business.

5. Maintenance and care of uninterruptible power supply (UPS):

A. Battery maintenance: The battery is one of the core components of UPS, and regular inspection and maintenance of the battery is crucial. Including checking whether the appearance of the battery is deformed, leaking, etc., measuring the battery voltage, internal resistance and other parameters to ensure that the battery is in good condition. It is generally recommended to deeply discharge and charge the battery every few months to activate the active substances of the battery and extend the battery life. For example, the UPS battery can be deeply discharged to about 50% once a quarter, and then fully charged.

B. Heat dissipation and cleaning: UPS generates heat during operation, and it is necessary to ensure that it dissipates heat well. Clean the dust inside and outside the UPS regularly, and check whether the cooling fan is operating normally. If the heat dissipation is poor, the internal temperature of the UPS may be too high, affecting the performance and life of the equipment. For example, you can use a compressed air tank to clean the dust on the UPS once a month, especially the heat sink and fan blades.

C. Regular inspection and calibration: Regularly inspect the various functions of the UPS, such as whether the output voltage, frequency and other parameters are normal, whether the conversion time meets the requirements, etc. At the same time, calibrate the voltage, frequency and other parameters of the UPS as needed to ensure that the output power quality is stable and reliable. Professional technicians can be invited to conduct a comprehensive inspection and calibration of the UPS every year.

In short: Uninterruptible power supply (UPS) plays an irreplaceable role in ensuring a stable power supply. Understanding its principles, types, parameters, application scenarios and maintenance knowledge can help us be more handy when choosing and using UPS, and ensure that our equipment and systems can operate safely and stably under any power conditions.