How does an UPS work?
An uninterruptible power supply (UPS), also known as a battery backup, provides backup power when your regular power source fails or voltage drops to an unacceptable level.
A UPS allows for the safe, orderly shutdown of a computer and connected equipment.
The size and design of a UPS determine how long it will supply power.
Different UPS topologies provide specific levels of power protection.
A UPSEN UPS will belong to one of these three topologies: standby, line interactive, and double-conversion.
Standby is the most basic UPS topology. A standby UPS resorts to battery backup power in the event of common power problems such as a blackout, voltage sag, or voltage surge.
When incoming utility power drops below or surges above safe voltage levels, the UPS switches to DC battery power and then inverts it to AC power to run connected equipment.
These models are designed for consumer electronics, entry-level computers, POS systems, security systems, and other basic electronic equipment.
A line interactive UPS incorporates technology which allows it to correct minor power fluctuations (under-voltages and over voltages) without switching to battery.
This type of UPS has an autotransformer that regulates low voltages (e.g., brownouts) and over voltages (e.g., swells) without having to switch to battery.
Line interactive UPS models are typically used for consumer electronics, PCs, gaming systems, home theater electronics, network equipment, and entry-to-mid-range servers.
They provide power during such events as a blackout, voltage sag, voltage surge, or over-voltage.
A double-conversion (online) UPS provides consistent, clean, and near perfect power regardless of the condition of incoming power.
This UPS converts incoming AC power to DC, and then back to AC. UPS systems with this technology operate on isolated DC power 100 percent of the time and have a zero transfer time because they never need to switch to DC power.
Double-conversion UPS systems are designed to protect mission-critical IT equipment, data center installations, high-end servers, large telecom installations and storage applications,
and advanced network equipment from damage caused by a power blackout, voltage sag, voltage surge, over voltage, voltage spike, frequency noise, frequency variation, or harmonic distortion.
Sine wave output: The highest quality waveform output is sine wave, which is a smooth, repetitive oscillation of AC power.
Enterprise-level UPS systems produce sine wave power to operate sensitive electronic equipment. Sine wave output ensures that equipment utilizing Active PFC power supplies do not shut down when switching from utility power to battery power.
Simulated sine wave output: An approximated sine wave output waveform. It uses pulse wave modulation to generate a stepped, approximated sine wave to supply more cost-effective battery backup power for equipment that does not require sine wave output.
The technology used to produce this type of power output is less expensive to manufacture and is common in standby and line interactive UPS systems.
How to maintain UPS uninterruptible power supply battery
The battery is an important part of the UPS uninterruptible power supply system. Reasonable maintenance of the battery can reduce the decay speed of the battery, increase the service life of the battery, greatly reduce the frequency of battery replacement, and effectively save operating costs.
1. Maintaining a suitable ambient temperature can prolong the service life of the UPS battery
Generally speaking, the factor that affects the UPS uninterrupted battery life is the ambient temperature. Generally, the best ambient temperature required by battery manufacturers is between 20-25°C. Although the increase in temperature has improved the discharge capacity of the battery, the price paid is that the life of the battery is greatly shortened. As indicated by the test outcomes, when the natural temperature is over 25℃, the life of UPS will be diminished significantly for every 10℃ of increment. At present, the batteries used in UPS are generally maintenance-free sealed lead-acid batteries, and the design life is generally 5 years, which can only be achieved under the environment required by the battery manufacturer. If it fails to meet the specified environmental requirements, its life span will vary greatly. In addition, the increase of the ambient temperature will lead to the enhancement of the internal chemical activity of the battery, thereby generating a large amount of heat energy, which will in turn increase the temperature of the surrounding environment. This vicious circle will accelerate the shortening of the battery life.
2. Regularly charge and discharge UPS uninterrupted battery
The floating charge voltage and discharge voltage in the UPS power supply have been adjusted to the rated value at the factory, and the discharge current increases with the increase of the load. The load should be adjusted reasonably during use, such as controlling electronic equipment such as a computer the number of units used. Under normal circumstances, the load should not exceed 60% of the rated load of the UPS. Within this range, the discharge current of the battery will not be over-discharged.
Because the UPS is connected to the mains for a long time, in an environment with high power supply quality and few occurrences of mains power outages, the battery will be in a floating charge state for a long time, which will lead to a decrease in the activity of the mutual conversion of chemical energy and electrical energy in the battery over time, and accelerate aging. And shorten the service life. Therefore, it should be fully discharged once every 2-3 months, and the discharge time can be determined according to the capacity of the battery and the size of the load. After a full load discharge, recharge for more than 8 hours according to the regulations.
3. Timely replacement of waste/bad UPS uninterruptible power supply batteries
At present, the number of storage batteries equipped with large and medium-sized UPS power supplies ranges from 3 to 80, or even more. These single batteries are connected through a circuit to form a battery pack to meet the needs of UPS DC power supply. In the continuous operation and use of UPS, due to the difference in performance and quality, it is inevitable that the performance of individual batteries will decline, and the storage capacity will not meet the requirements and be damaged. When some/some batteries in the battery pack are damaged, maintenance personnel should check and test each battery to exclude damaged batteries. When replacing a new battery, you should try to buy the same type of battery from the same manufacturer, and it is forbidden to mix acid-proof batteries, sealed batteries, and batteries of different specifications.
What is a True Modular UPS?
When selecting a UPS system, the up-front cost necessarily comes into question and this can lead organisations sometimes buying a lesser product at a lesser cost. However, it is essential to check the small print to ensure you have chosen a modular system that it really will do the job intended: protect the critical power of your datacentre with the highest level of availability. Interestingly, with some of the higher quality UPS systems, cost savings are often realised over the long-term through increased efficiency, resulting in lower running costs and a lower overall total cost of ownership (TCO) so doing a full cost analysis is usually worth calculating.
So, as their primary goal, how can datacentres select a UPS to maximise availability? Essentially, there must be no potential single points of failure. Understanding the configuration and the definition of a modular system carefully, before the deal is done, is critical.
At the most basic level, a single standalone UPS unit that protects a critical load is known as an N system configuration. However, a standalone UPS lacks any resilience in the event that the unit develops a fault or is offline for preventative maintenance. Paralleling a second standalone UPS unit of the same rating, provides resilience and is known as an N+1 configuration. It would be possible parallel several standalone units together of an individual smaller rating to give the same philosophy.
Another definition of modular is a standalone UPS designed and manufactured in a modular format. The main component parts of rectifier, inverter and static switch are modular. If there is a problem with say the rectifier for example, it can be swapped easily. The challenge with this configuration is that if one component does fail the whole UPS functionality goes down with it. It may be a modular system, but its level of availability will not be reliable.
A better solution is what we term: a true modular UPS. This is where several individual UPS modules are contained within a frame. All the individual modules are UPSs in their own right, all containing a rectifier, inverter and static switch and all operating online in parallel with each other. For example, six 50kW UPS modules may typically be contained within a single frame offering a resilient configuration of 300KWs N+1. If required, it takes moments (around 30 seconds) to ‘hot-swap’ a module while the rest of the modules continue to protect the critical load.
At no point does the system need to be transferred to maintenance bypass and hence on raw mains.
Some other modular systems include the rectifier and inverter within their modules, but the static switch is centralised and separate. This results in a potential single point of failure. It may only take a few moments to replace a separate static switch, but, depending on location, getting to the site to replace it may take a maintenance engineer several hours. During that time the system cannot transfer to static bypass. With a true modular system, where the static switch is included in each module, the rest of the modules in the UPS frame continue to protect the load until it can be replaced. This increases the level of availability dramatically.
We have developed our latest generation true modular UPS system which offers power factory of more than 0.99 , with low total cost of ownership (TCO) through its Maximum Efficiency Management (MEM) and low losses of energy. Our design team has been working with data centres for many years at the forefront of technological development.
Solar controller's three-stage charging mode
- The PWM solar controller adopts three charging modes of strong charge, balanced charge and floating charge.
also called direct charge, is fast charge, when the battery voltage is low, with high current and relatively high voltage to charge the battery.
After the intensive charging is complete, the battery will stand for a period of time. When the voltage drops to a certain value, the battery
will enter the balanced charging state to ensure uniform and consistent battery terminal voltage.
After the equalization charge is complete, the battery also stands for a period of time. When the voltage drops to the maintenance voltage,
the battery is in the floating charge stage, so that the battery can be kept in the charging state without overcharging.
- MPPT solar controller adopts MPPT limited current charging, constant voltage equalization charging and constant voltage floating charging mode.
MPPT limited current charging:
in the battery voltage is very small, the use of MPPT charging mode, the output power of the solar panel pumped to the battery end, the light intensity is very strong,
the output power of the solar panel increases, the charging current reaches the threshold, the TERMINATION of MPPT charging into constant current charging;
When the light intensity becomes weak, it will turn to MPPT charging mode.
Constant voltage charging:
the battery in MPPT charging mode and constant current charging mode free switch, cooperate with each other so that the battery voltage reached the saturation voltage,
it entered the constant voltage charging stage, with the battery charging current gradually decreased to 0.01c, the charging stage terminated, into the floating charge stage.
Constant voltage floating charge:
the battery is charged with a voltage slightly lower than the constant voltage.
This stage is mainly used to supplement the energy consumed by the battery self-discharge.
The difference between high frequency UPS and low frequency UPS
- 1. High-frequency machine:
Using high-frequency switching technology, high-frequency switching elements are used to replace the UPS of power frequency transformers in rectifiers and inverters,
commonly known as high-frequency machines. High-frequency machines are small in size and high in efficiency.
- 2. Power frequency machine:
UPS using power frequency transformer as rectifier and inverter components is commonly known as power frequency machine.
High frequency machine VS industrial frequency machine
- 2-1: The high-frequency machine does not have an isolation transformer, and its output zero line has high-frequency current, which mainly comes from the harmonic interference of the mains grid, the pulsating current of the UPS rectifier and the high-frequency inverter, and the harmonic interference of the load. The interference voltage is not only high in value but also difficult to eliminate. However, the output zero-ground voltage of the power frequency machine is lower, and there is no high-frequency component, which is more important for the communication security of the computer network.
- 2-2: There is no transformer isolation for the output of the high-frequency machine. If the inverter power device is short-circuited, the high DC voltage on the DC bus (DCBUS) will be directly applied to the load, which is a safety hazard, but the power frequency machine does not exist. question.
- 2-3: The power frequency machine has strong anti-load impact ability.
Principle and function of inverter soft start
- Principle of inverter soft start:
1.Inverter soft start means that the voltage is gradually increased from zero to the rated voltage, so that there is no impact torque in the whole process of starting the motor, but a smooth start-up operation.
2.The soft starter is a novel motor control device that integrates motor soft start, soft stop, and multiple protection functions. Its main composition is a three-phase parallel thyristor and its electronic control circuit connected in series between the power supply and the controlled motor. Use different methods to control the conduction angle of the three-phase inverted parallel thyristor, so that the input voltage of the controlled motor changes according to different requirements, and different functions can be realized.
- The function of the inverter soft start function:
1.At the moment when the inverter is powered on, the inverter is powered, but there will be a delay of about 2 seconds when outputting 220V. The voltage will not reach 220V immediately, but will slowly rise from 100V to 220V, yes. Protection of the inverter itself.
2.For example, a normal inverter with 1000W power will output 1000W when the inverter is powered on. If it is a soft start, the output will continue to rise, 700W-800W-900W-1000W.
What is the advantage of lithium battery?
- 1. The energy ratio is relatively high. With high storage energy density, it has reached 460-600Wh/kg, which is about 6-7 times that of lead-acid batteries;
- 2. The service life is long, and the service life can reach more than 6 years. The battery with lithium iron phosphate as the positive electrode is charged and discharged at 1C (100% DOD), and has a record of 10,000 times of use;
- 3. The rated voltage is high (the single working voltage is 3.7V or 3.2V), which is approximately equal to the series voltage of 3 nickel-cadmium or nickel-metal hydride rechargeable batteries, which is convenient to form a battery power pack;
- 4. With high power endurance, the lithium iron phosphate lithium ion battery used in electric vehicles can reach 15-30C charge and discharge capacity, which is convenient for high-intensity start-up acceleration;
- 5. The self-discharge rate is very low, which is one of the most prominent advantages of the battery. Currently, it can generally achieve less than 1%/month, which is less than 1/20 of the nickel-hydrogen battery;
- 6. Light weight, the weight is about 1/5-6 of the lead-acid product under the same volume;
- 7. Strong adaptability to high and low temperature, it can be used in the environment of -20℃--60℃, after the process is processed, it can be used in the environment of -45℃;
- 8. Green and environmental protection, no matter it is produced, used or scrapped, it does not contain or produce any toxic and harmful heavy metal elements and substances such as lead, mercury, cadmium, etc；
- 9. Production basically does not consume water, which is very beneficial to countries that lack water.
How to divide low frequency UPS and high frequency UPS ？
Colloquially speaking, The UPS contains isolation transformer UPS called Low frequency UPS, there is no transformer UPS is high-frequency UPS
The advantages and disadvantages of respective are as follows:
- 1-High-frequency UPS: Using high-frequency switching technology to replace the UPS power supply of the power frequency transformer in the rectifier and inverter with high-frequency switching components, commonly known as high-frequency UPS, high-frequency UPS is small in size and high in efficiency.
- 2-Low frequency UPS: UPS power supply using low frequency transformer as rectifier and inverter components that is commonly called low frequency UPS. The main power components features are stable and reliable , strong overload capacity,anti-impact ,anti-interference ability, and strong load capacity.
- 3-The high frequency UPS power supply does not have an isolation transformer, and its output zero line has high-frequency current, mainly from harmonic interference of the mains grid, UPS rectifier, high-frequency inverter ripple current and harmonic interference of the load, etc., and its interference voltage value is not only high and difficult to eliminate.The output of the low frequency UPS power supply has a lower zero ground voltage, and there is no high frequency component, which is more important for the communication security of the computer network.
- 4-The high frequency UPS power supply is small in size, light in weight, low in price, that is suitable for small power equipment protection at a single working point.High frequency UPS is insensitive to interference-insensitive equipment and reliability.The low frequency UPS is suitable for all equipment protection. Whether it is a network point equipment or an IDC (data center), the reliability is high.But the low frequency UPS has the disadvantages of large volume, heavy weight and high price.
- 5-The high frequency UPS power supply adopts IGBT rectification and inverter, and does not need the output transformer to boost, so there is no output isolation transformer. the volume is also relatively small and suitable for low-power power supply.The low frequency UPS power supply adopts thyristor rectification. After the inverter, it needs to be boosted by the transformer to supply power normally. Therefore, there is an output isolation transformer, the transformer volume is also relatively large, which is suitable for high power supply.
Comprehensive Comparison Between Lithium Batteries and Lead-Acid Batteries
How to use the inverter correctly?
Issues that need to be paid attention to when using the inverter:
- The DC voltage must be consistent
Each inverter has a DC voltage value, such as 12V, 24V, etc. It is required that the battery voltage selected must be consistent with the DC input voltage of the inverter. For example, a 12V battery must be selected for a 12V inverter.
- The output power of the inverter must be greater than the power used by the electrical appliances, especially for electrical appliances with high power when starting, such as refrigerators and air conditioners, a larger margin should be left.
- The positive and negative poles must be connected correctly
The DC voltage connected to the inverter is marked with positive and negative poles. Red is positive (+), black is negative (-), the battery is also marked with positive and negative, red is positive (+), black is negative (-), must be connected to positive (red to red), negative Connect negative (black connect black). The diameter of the connecting wire must be thick enough, and the length of the connecting wire must be reduced as much as possible.
- It should be placed in a ventilated and dry place, beware of rain, and have a distance of more than 500px from surrounding objects, away from flammable and explosive materials, and do not place or cover other objects on the machine. The use environment temperature is not more than 40℃ .
- Charging and inverter cannot be performed at the same time. That is, do not insert the charging plug into the electrical circuit of the inverter output during inverter.
- The interval between two startups is not less than 5 seconds (cut off the input power).
- Please wipe with a dry cloth or anti-static cloth to keep the machine tidy.
- Before connecting the input and output of the machine, please ground the casing of the machine correctly.
- In order to avoid accidents, it is strictly forbidden for users to open the case for operation and use.
When you suspect that the machine is malfunctioning, please do not continue to operate and use it.
- When connecting the battery, make sure that there are no other metal objects on your hands to avoid short circuit of the battery and burn the human body.
- The use environment, based on safety and performance considerations, the installation environment should have the following conditions:
1) Dry: not soaking or raining;
2) Shady and cool: the temperature is between 0℃ and 40℃;
3) Ventilation: Keep no foreign matter within 5cm on the shell, and the other end faces are well ventilated.
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How to maintain UPS?
- 1. Maintenance of the venue
(1)When installing and using UPS, the temperature of the installation and use environment should be 0~40℃, and the relative humidity should be 30%~90%.
(2)If the temperature is lower than 0°C or damp, the insulation performance of the UPS power supply will decrease, which will easily cause a short circuit. At the same time, it may also cause corrosion and rust on the connectors of the UPS power supply and other equipment, electrical connection screws, component pins, and solder joints.
(3)Altitude>1000m, derate 10% for every 1000m drop.
(4)Do not place strong magnetic objects on the UPS, otherwise it will cause the UPS to work abnormally or damage the machine.
- 2.The maintenance of the battery
The battery is a UPS as a device for storing electrical energy, and the size of the capacity determines the sustaining discharge time.
(1) Maintain a suitable ambient temperature
Considering all aspects, UPS uninterruptible power supplies generally use maintenance-free lead-acid batteries with a life span of about 5 years. The battery operating environment temperature is between 20~25℃. Once it exceeds 25℃, every 10℃ increase will reduce the battery life by half.
(2) Regular charging and discharging of the battery
In an environment where mains power outages rarely occur, the battery will be in a floating charge state for a long time, which will lead to a decrease in the activity of the battery's chemical energy and electrical energy conversion, accelerating aging and shortening its service life. Therefore, it should be completely discharged every 2-3 months, and the discharge time can be determined according to the capacity of the battery and the size of the load. After a full-load discharge is completed, charge it for more than 8 hours according to regulations.
Do you know there are several types of UPS?
UPS can be broadly divided into three types: Off Line, Online and Line interactive.
- What is an offline uninterruptible power supply (OffLine UPS)
The offline uninterruptible power supply is shown above. Normally, the electricity is supplied directly to the load via a bypass. Only in the event of a power failure does the battery energy convert to AC to provide power to the load through an inverter. Features of offline uninterruptible power supplies:
When the current power is normal, offline UPS does not have any treatment of the power and directly output to the load, so the ability to suppress the electrified noise and surge is poor;
There is a conversion time;
The worst protection performance;
Simple structure, small size, light weight, easy control, low cost
- What is an on-line uninterruptible power supply (On-Line UPS)
The online UPS is normally powered to the load by an inverter output and is only converted to a bypass output to the load if the UPS fails, overloads, or overheats. Features of online UPS:
The output power is processed by UPS, and the output power supply quality is the highest.
No conversion time;
Complex structure, high cost;
The best protection performance and the strongest resistance to electrified noise and surges.
- what is the online interactive uninterruptible power supply (Line interactive UPS)
Online interactive UPS is usually output to the load by bypass transformer, and the inverter is now used as a charger. When power is lost, the inverter converts battery energy to AC output to the load.
Features of online interactive UPS:
With bidirectional converter design, UPS battery recharge time is short;
There is a conversion time;
The control structure is complex and the cost is high.
Protection is between online and offline UPS, and the suppression of electrified noise and surges is poor.
How to buy a suitable UPS that you need?
If you want to buy a UPS that suits your needs, you have to consider many factors, the most important of which is to determine the power of the UPS, and then determine the type of UPS according to the load and grid environment.
UPS types are divided into: online UPS, interactive UPS, Backup UPS. Choose the installation method according to the use environment, tower UPS and rack UPS.
These are several more important factors. Others can also consider the manufacturer’s service capacity, battery life, etc. I think the right choice The power of the UPS is very important, because if the occasion is small, a high-power UPS will be wasted. For small occasions such as an office or one or two servers, a small power is enough, and there is no need to use too much power.
Now there are many brands of low-power UPS available, and various manufacturers have corresponding products. For example, UPSEN has several Online UPS like: DC UPS, Queen Star, Century Star these models, the cost performance is reasonable, the reliability and environmental adaptability are also really good.
Notes for using lead acid battery
How to improve the reliability of UPS ?
- Add parallel battery packs：UPS using a single set of series batteries are more risky for normal power supply loads.
When connected in series, if there is a problem with one battery, it will affect the discharge of the entire battery pack, which will cause the UPS to fail to supply power.
When connected in parallel, if one of the battery packs fails, but the UPS can still be powered by another normal battery pack for a period of time, so that there is time to connect the standby generator to supply power or time to shut down the load device.
- The installation of diesel generators: battery power can only solve the urgent need for a moment.
If you face a long power outage, even the longest battery pack may not work. Therefore, in the case of a long power outage, it is desirable to use a diesel generator as a backup power supply.
- Increase availability by installing an UPS
Redundant design logic not only applies to power protection schemes, but also to UPS designs. Building multiple power paths in a power supply design can radically improve system reliability.
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