15 Essential Questions and Answers About UPS

Time of issue:2022-03-14


Due to the development of information technology, the network has become an indispensable part of people's life and work. The reliability of the power supply of the digital computer room that constitutes the network has become the key, and the reliable power supply of the computer room is the top priority, and the UPS is existed to provide Uninterrupted power supply.


1. Why use UPS? What is the role of UPS?


Due to the development of information technology, the network has become an indispensable part of people's life and work. The reliability of the power supply of the digital computer room that constitutes the network has become the key, and the reliable power supply of the computer room is the top priority. set for intermittent power supply.


The three basic functions of UPS: voltage regulation, filtering, uninterrupted.


When the mains power supply, it is the function of the voltage stabilizer and filter to ensure the normal operation of the equipment; when the mains power is interrupted, it can pass the DC power provided by its DC power supply part (battery pack, diesel generator, etc.) It is converted into a perfect AC power supply for the load, in which the switch from the mains power supply to the battery power supply is generally 0 time switching, so that the load device can keep running without feeling any change, and truly ensure the uninterrupted operation of the device.


2. Is the UPS generally capable of inductive load or capacitive load? Why?


Generally, UPS is designed according to inductive load, so it is its duty to carry inductive load. Generally, the capacitor connected in parallel at the output end of the UPS inverter plays a filtering role on the one hand, and cancels the inductive component in the load on the other hand.


If the load is capacitive, how to use the capacitor to cancel the capacitive component? Only the output capacitance component can be increased, and the current of these capacitance components must be provided by the inverter, so that the active component output by the inverter is reduced, so the load-carrying ability is weakened.


3. What is the function of STS (static switch), LBS (synchronizer) and dual bus?


The role of STS is to switch the two input AC power.


The role of the LBS is to synchronize the two sets of UPS, and the purpose is to make the switching time of the STS zero.


The function of the dual bus is to provide redundant power to the electrical equipment.


4. What is the main difference between EPS and online UPS? What is the main use of both?


Similar to UPS: EPS is a 100% backup UPS, it works the same as a backup UPS.


Differences: EPS has different loads, such as lighting and starting water pumps, etc., the power needs to be very large, and the inverter can be made into a frequency converter when starting the water pump; while the backup UPS is mainly based on PCs. Such as IT equipment, so the capacity rarely exceeds 3KVA.


Generally, IT equipment above 3KVA uses online UPS. In IT equipment occasions, EPS cannot be used anyway.


5. What are the advantages and disadvantages of the power frequency UPS and the high frequency UPS? Can the high frequency UPS replace the power frequency UPS?


Power frequency UPS: The disadvantage is that the input power factor is low, the power consumption is high, the efficiency is low, the volume is large, the bulk is heavy, the price is high, and the reliability is low; relatively low.


High-frequency UPS: The advantages are high input power factor, low power consumption, high efficiency, small size, light weight, and high reliability; but it has high requirements for production methods and strict requirements for consistency.


6. Why is the capacity of UPS expressed in VA? What is this power called?


The unit of active power is watt (W), and the unit of reactive power is var (var). Generally, the capacity of UPS is expressed by apparent power. Since apparent power includes both active power and reactive power, it can neither be called W nor var. Since apparent power is volts (V) and amperes ( A), simply called VA.


7. What is active power and what is reactive power?


Active power refers to the power that can make a load do work, such as making a light bulb glow, making a circuit work, and so on. After the work is done, it is completely turned into heat and dissipated into the atmosphere, and it is gone forever.


Reactive power refers to the power stored in energy storage devices (devices), which can be converted into active power.


8. What is the definition of UPS efficiency? What does it stand for? Is it the same thing as power factor?


The definition of η of UPS efficiency is: the percentage of the ratio of output active power P to input active power P', namely: η=(P/P')%. It is a sign to measure the power consumption of UPS. And power factor is not the same thing.


9. What is the capacity unit of the battery? What does it mean?


The capacity unit of the battery is ampere-hour, referred to as ampere-hour (AH). For example, a battery with a discharge rate of 10 and a capacity of 100AH, is discharged with a constant current of 10A for 10H, and the released capacity is 100AH.


10. What are the benefits for users to understand the development of UPS?


The main purpose of understanding the development direction of UPS is to prevent users from purchasing equipment that has been outdated and has been eliminated or will be eliminated soon, so as to avoid unnecessary losses.


At present, UPS has developed into an online parallel redundant modular solution system UPS. Both channel dealers and users can realize that modularization has come, and it will replace the application of traditional UPS in data room.


11. What is the development trend of UPS?


The main purpose of developing UPS technology is to improve the dynamic response of UPS to the output load, which is faster and better. Obviously, the use of advanced high frequency technology has the fastest dynamic response and the best effect.


12. Can the traditional power frequency machine with output isolation transformer increase the load capacity and reduce the neutral ground voltage?


Strictly speaking, the output isolation transformer of the power frequency machine is an indispensable component of its inverter part, and there is no full isolation effect, because the bypass has no isolation and the zero line has no isolation.


13. Is there lightning protection on the UPS?


The UPS can be equipped with an optional input C-level lightning protection, which has two ways:


①Lightning protection with the priority of protecting the load;


②The lightning protection is given priority to protect the power supply, but it has little effect. Because the UPS is equipped with lightning protection, at best, it can only save the first-level lightning protection in the power distribution cabinet, but the lightning protection device cannot be omitted in the power distribution.


Lightning protection is a very secondary factor in UPS selection.


14. Can UPS with isolation transformer enhance its anti-overload capability?


Wrong, that is the slow response speed, the UPS will jump to bypass work after overload, and then resume rectification and inverter work when the load is normal. Should be through the upgrade of UPS capacity to meet the growing need for expansion of the load.


15. Is the quality of power frequency UPS more stable?


Some high-frequency UPSs have poor quality due to reduced production costs, production conditions and backward design. In order to keep up with market trends, improve efficiency, be more environmentally friendly and save energy, it is necessary to choose a well-known modular UPS brand.