What is UPS?
Science and technology constantly improve, has brought comfort and convenience for life, we accidentally relied on automation equipment of science and technology, but we also met inconvenience when power outages, problems of automation. Most electrical equipment is not sensitive to a power outage, but when power is restored, it can continue to operate.
For example, elevators, televisions, washing machines, refrigerators … But some sophisticated devices are very sensitive when power is cut off, not only causing great losses, and life can be threatened when serious happens, for example, large computer rigs, securities trading, chip components manufacturing, pulmonary cardiometers, navigation devices …
Generator is a common power supply during a power outage, will provide power to the device during a power outage, the start speed of any generator, no matter how fast, from after a power outage until the generator receives the signal that needs to be started to generate electricity, until the voltage, the frequency of the generator is stable so that it can supply electricity, it takes ten seconds or a few minutes. This, the electrical equipment must stop working, so it can damage the equipment or bring loss to property and life, from which we see the generator can not completely satisfy the demand used for electrical equipment.
UPS will provide non-stop and stable AC power to serve computers and other important devices when the city electricity supply erratically, electrical equipment is still working normally, no damage and paralysis.
We will introduce the structure and important characteristics of the electricity storage devices, to give readers a deep understanding of the structure and functions of the power saving devices, increasing the awareness of the application of the fields. In different areas, knowing what equipment can serve us, choosing which product is appropriate, to have a highly effective application.
Type of system
When distinguishing between structures, the UPS (Uninterruptible Power Supply System) is broadly divided into two types: pure and dynamic. Generate electricity by motor, motor, generator, flywheel, assembled as a driving force. Can be divided into linear and linear form, the form on the line is all or part of the UPS device placed in the middle of the current and load, with isolation. The route type in the hot state is waiting for use, only when the power is turned off, it is not possible to isolate the current of bad quality due to harassment, high pressure, low pressure, change in the system. power supply system, unless the financial capacity is tight, do not use this type should not be introduced in this article.
Net form UPS
Main structure includes:
1. Charging circuit / rectifier
3. Converter set
4. Pure switch only
5. Turn line protection
6. Coordinated isolation transformer circuit
UPS dynamic form
The type of product is very dynamic, the common feature of all kinds of products is the use of dynamic components such as flywheels or flywheel-like types to convert power (between the city’s power supply equipment). and power supply source) will release stored energy, to be a relay bridge, to provide electricity when the current is disconnected or when the load-bearing closed circuit is short-circuited, provides a large power supply and eliminates the trouble about isolation.
In this system, if differentiated by structure, can be divided into two types: full dynamics and different major mix forms made by components.
Full dynamic form
(1) Electric coil
(2) Synchronous machine (motor generator set)
(3) Clutch kit
(5) Energy storage equipment (like flywheel equipment)
(6) Turn line protection
(1) Electric slide and electric current switch
(2) Energy storage equipment
(3) Charger / converter
(5) Electric motor
(6) Turn line protection.
The working status of the system
When operating normally
The system is supplied with electricity by the city electricity, after passing the charger / rectifier, a small part will be transferred to the battery, most of which is converted into alternating current through the adapter to provide For the load, the output power of the converter must be synchronized with the power of the turn line and the power supply line. Because the input and output power needs to pass through the charger / rectifier and converter, there may be signals: in a suspended state, low voltage, momentary power outages, resonance waves and signals. signal interference etc. and this situation does not propagate to the output, this is one of the great uses of the UPS form on the route.
When the system is unusual
(1) When the AC power supply is abnormal, the converter is powered from a fully charged battery, the AC power from the output provides the machine to operate freely. (The so-called free operation does not need to be synchronized with any power source but the frequency remains at 60 b 0.5 Hz).
(2) Rectifier / rectifier malfunction
This is the case but the inverter’s output power is still in sync with the power line.
(3) Malfunction in the converter The pure-format switch only immediately transforms the load to the power source of the turn, the so-called “non-breaker” refers to this condition, the switching action of the switch Net form only needs to be fast, fast to the point where the electrical equipment is using and can not feel and still work normally. Because the net form UPS only judges whether the power supply is normal or not, by checking the voltage of the input, there is a “disruption” which causes the conversion (ie, the previous connection is interrupted). In other words, the “no break” or “momentary break” is really suitable. This “momentary” delay is usually less than 4ms (milliseconds); After the converter turns out to normal power, the load switches back to the adapter.
(4) Automatic recovery function occurs when unusual situations such as overload, overheating, short-circuit load without the problem of the adapter, the pure switch switch is only instantly converted. load as the power line turn, after excluding the above causes, the net switch only automatically switches the power line back to the adapter, return to the state.
Repairing turn switches and related switches will completely isolate the electrical carrying parts of the converter and the provincial switch only, ensuring no electric shock when repairing.
Full dynamic form
When operating normally
The system is supplied with electricity from the city electricity, supplied to the load using electric motor roll, a small part is supplied to the synchronous machine and flywheel to supplement the loss for friction to maintain kinetic energy. . The external synchronous machine has the function of making the output voltage stable, and also has the function of providing invalid power to improve the input power factor to be close to one. Through the action of the electric motor roll and the synchronous machine, an unbalanced load current can be controlled, so that the input current is balanced.
Therefore, any resonant wave due to the output line produced or most of the input resonant wave is reduced. The electric motor coil can also separate the voltage disturbed by the noise signal in the input power source.
The pure state motor, which is hot and greasy, makes the engine in its state able to start at any time, the clutch becomes an open path (open).
When the power goes out
When the tracking system detects the current due to the outage of the city, the open input switch, lends the energy released by the storage device, the temporary motor becomes a generator, continues to supply Power supply for load bearing. At the same time immediately start the engine, after reaching a stable speed within 2 seconds, the clutch closes, the flywheel transmission motor and the synchronous machine have a slow speed of slowing down, the working state job. It should be noted that if the engine cannot start smoothly, the clutch will be forcibly closed, taking advantage of the rotation of the motor pass synchronous motor. This is called high-speed start-up, to avoid a power outage.
When there is electricity again
When the electric current is supplied again, over a period of time, it is planned to return to using the city’s current to provide simultaneous open clutches, engine stops, and return systems.
The closed turn line switch, the input and output switch open, the transfer load provided through the closed circuit of the turn line switch, the rotation speed of the synchronous machine decreases gradually to stop.
It is a combination of motive and pure components, providing stable and stable current. This is just one of the mixed forms.
The storage device of this type is the engine components, with the charger and the converter to supplement the power supply for the power outage time is too long, can also be equipped with other engines to provide electricity. The storage device can be divided into a motor and a generator. Could also be a kind of unity. The function of these two types is the same but the different structure is different in performance, here it takes the consolidation type as an example.
When operating normally
When normal, the current through the breaker switch, electric slide block, power storage device to load, the circuit breaker has the function of preventing short-circuit current at the input, avoiding the energy source being sucked away; the electric motor block will limit the maximum powerless capacity; closed circuit of the input current will be converted into alternating current through the charging machine, on the one hand to charge the battery, and on the other hand supply the converter to convert it into a synchronous AC current with the input of the device. hot storage, formed hot stand state.
When the power goes out
When the system detects that the city current is disconnected, the input switch is turned off, the converter provides electricity immediately, and the battery starts to discharge. At the same time, with temporary energy storage, the power storage device also temporarily provides power to the load, so, like the full-power UPS, is a complete type of electrical device, there is a peace of mind compared to the form. The motivation is: a few minutes to ten minutes after a power outage and a power supply converter, unlike the full-power model that takes a few seconds to start the engine with a worry about the supply Power supply is interrupted. The battery power supply time is limited, usually from 15-30 minutes, beyond this time, the system is still in use, if you want to extend the power supply for extended power outages, It is possible to attach a motor to promote the synchronous machine, only need fuel, can extend the time of power supply.
Turn off the circuit, the switch turns off, the switch is turned on and off, the load is provided through the closed circuit of the turn-off switch, the rotation speed of the synchronous machine decreases gradually to stop.
Overview of functions
UPS only net
Recharge circuit / rectifier
The main function of this device is to convert alternating current into direct current, one side supplying the converter to an alternating current to reach the load, otherwise charging the battery. The capacity of this device in addition to the full supply of electricity, also need 10-25% more to provide for charging.
In the pure UPS, the battery is very important, when the power goes out without it, the UPS also stops, so the UPS also expires as a UPS. The electricity storage time of normal battery is 10-15 minutes, depending on the power supply status of the city, whether it is necessary to prepare the generator itself, load-bearing level and economic factors, etc. Long or short reserves with no bronze, some cases are 1-3 hours long. But how long the battery’s storage time is, if in a long time the battery capacity is very large, not only occupying a large area, the investment budget is also high, so invest in a generator.
In the pure form, the converter is the heart of the UPS, the converter transforms direct current from the battery or rectifier into alternating current to provide good or bad UPS power, The decision of the converter completely, in the form of the converter’s electrical output mix, must go through the synchronous machine, the quality of the filtered power should not be strict for the converter’s waveform output requirements, Even square wave is fine.
Turn off net format conversion only
In pure UPS only, if for the converter is the heart of UPS, the STS can assume that the soul of UPS, because between the two power sources, the UPS converts the speed ratio less than 4ms, without interrupting the power , STS is the number one spirit.
STS can be divided into mechanical and electronic forms. The mechanical form uses electronic switches or ordinary breakers. When switching, the breaking power is about 50-250ms. The so-called “breakdown” starts from when the voltage is lower than the allowable value (normally set to 85%) until the transition is completed and the voltage returns to normal. The speed of reconnaissance is very fast but the conversion is very slow, the sophisticated devices or computers will not be able to withstand. The electronic speed of STS is shorter than 4ms, the conversion action is only 0.5 ms, so the time in the middle of the power is shorter than 4.5ms, which can be satisfied for the needs of some normal computers and Some sophisticated devices.
The structure of the electronic tool can be divided into a permanent fixed form and a mixed form as follows:
(1) Fixed whole state form
STS is a fixed state of the fixed state from SCR, has practical effects, few problems but due to the continuous operation, STS needs to use “continuous operation level”, the price is quite high. And when SCR has electricity going through, it will produce low voltage, not only will the loss of electricity (about 1 ~ 2%) also increase the load of the air conditioner, so the productivity is quite low.
In the figure, the power supplied by the converter passes from # 1 SCR, the current supplied by the city converts from # 2 SCR to the load, when normally only the # 1 SCR is passed, when the shaft converter If it is repaired or repaired, it is from the # 2 SCR group, the switching signal between these 2 SCRs is controlled by the circuit.
(2) Mixed form
The fixed whole state type has the disadvantage of high power consumption, energy waste, high cost and increased air conditioner load, so there are still mixed users.
When normal, CB2 ON, CB1 OFF Sw in position 1, load the power supply from the converter, when the adapter malfunctions or when repairing, CB1 On, CB2 Off and Sw in position 2, load be delivered electricity supply from the city. The conversion process is as follows:
(A) When the adapter malfunctions or repairs
SCR OFF or SCR ON and CB2 OFF, CB1 ON
(B) When recovering
(a), CB2 ON, CB1 OFF or SCR ON SCR OFF.
Since then we know a few things: 1. SCR only undertakes power supply during transition period, once CB1 ON or SW moves to position 2, SCR exits. 2. SCR is not a continuous operation, so its capacity may be smaller than 3. During the transition, it must be “followed by a break after”, two power sources are connected in one place, so the Sync is important.
CB and SW of the mixed form if during the unfavorable transition (for example, being stuck), SCR cannot guarantee the continuous use will be burnt, which is also a disadvantage of the mixed form, the user needs to concentrate Special attention.
Turn protection switch
After a period of use, the UPS needs to maintain, this switch can provide a path that is not completely related to the UPS, UPS can safely shutdown for repair and maintenance. But this is a final power supply circuit, if unfortunately, the power company has to power off again, will not avoid the machine must be turned off, so open the generator before repair, will safer.
The transformer separates the combined cup
If the switching power supply voltage (eg 3 4, 4W, 380v) and the voltage of electrical equipment used (eg 3ψ, 4W, 208/120v) in different power supply systems, the UPS system needs including this device. This device makes the power line voltage completely the same as the output voltage of the converter, so that when the above problem occurs, the load may not be interrupted when switching between the two power sources.
UPS full-force form:
Electric dynamic coil
As mentioned above, mainly components isolate high-frequency interference and resonant wave component of power source and load. It also means that the resonant waves due to the production load will not be able to transmit to the power source and the resonant, the signal spurred by the power supply cannot reach the load side.
Synchronous machine (motor generator set)
When city electricity is provided normally, the synchronous machine is supplied with energy from the city power source to maintain movement (large energy to start the supply motor) acting as a motor, but can Maintain stable voltage due to modulating load variation giving voltage. Disabled power will be supplied by the synchronous machine, so regardless of the load factor, the input power factor can be adjusted to 1. When the city power is cut off, the synchronous machine Immediately become a generator, convert the energy stored in the storage device into electricity to continue supplying electricity to the load. The storage device can immediately release electricity, so the short-circuited capacity will be more than the pure UPS only.
The clutch has two functions, one is when the system starts to serve, the motor needs to be pulled along with the synchronous motion machine, when the motor moves close to the specified speed, the dual clutch gradually progresses, the copper set and storage device accelerates gradually to the specified speed. Type 2 is after normal service, if the city electricity is disconnected, the motor can start loads at a rapid speed, increasing the chances of a successful start, the dual clutch after the motor starts dynamic, power supply from motor.
Just like a normal motor, only fuel can be used, with unlimited time movement.
Power storage device (as a flywheel device).
When a power outage releases energy, but the energy reserve will be limited, only an estimate of less than 2 seconds can be provided, during this time, the motor needs to start smoothly to provide resistance. load, to avoid interrupted power supply.
Turn protection switch
Just like the pure form, this switch provides the router when repairing the system.
Electric slide and electric switch
The electric motor coil is designed between the city power source and the storage device, if the voltage fluctuation rate of the city current is less than ± 15%, it is possible to reduce the power from the city current to the and go to the power storage device.
When short-circuiting the electrical side, to avoid the energy loss, so the electrical switch is also designed in the middle of the city current and the storage device, when short-circuiting in the electric side of the city, the electrical switch immediately open, isolate the system and malfunction.
Power storage device
The motor’s wire and the generator together wrap on the same Stator, forming a very special transformer, motor coil is a single track, the generator coil is two times monitored. When the current enters the filament wire, it will produce a rotating magnetic field, coil two as a transformer that produces the output voltage at the generator coil, and this rotating magnetic field pulls the moving Rotor. , acting as induction motor. Conventional transformers do not have a way to prevent one-time resonance or variable voltage transmission to two times, but this type of machine has a rotor, only need to control the excitation current of Rotor can control the current. The output is relatively good without the influence of one-time resonance or switching resonance waves. The main mechanism for detonating resonant waves: in Damper Windings with a design that works to reduce the production of resonant waves.
In the dynamic type UPS, this type of structure has some characteristics as follows: one-time energy to two times without switching with high-performance, high-performance mechanical methods; Voltage once and voltage twice have one engraving; motor and generator set into one body, the volume of the rotor volume can be supplied to compensate for the outage in the transitional period; has great inertia kinetic energy, short-circuiting capacity.
Charger circuit / adapter
The structure and function is the same as the charger / converter of the pure type only, but because the charging circuit only suffers from no-load losses of the adapter and the floating power of the battery should be smaller than the capacity.
Just like the battery of net form only.
Like the motor of full-force form, but because of the battery, it is not necessarily necessary.
Turn protection switch.
Like a switch to protect the turn of a full-force form.
Selection and application
After understanding the structure of UPS and its components, it will be followed by how to choose a suitable kit for your needs and systems to buy a high quality UPS, less trouble for life. long..
Recharge circuit / rectifier
Characteristics of the primary survey:
After having the power again, due to having to supply electricity at the same time for loading and charging the battery, when recharging the battery needs a very large current, the characteristics here can avoid overloading the machine. Loaded, can also avoid excessive charging current of battery. The term limit can be adjusted according to the load-bearing state from 50 ~ 110%.
Slow start (walk-in or Soft Start)
Gradually improving to produce voltage, electric power is also gradually enhanced, in addition to protecting the wave filter components itself without being damaged by large currents, can also avoid lowering voltages or generators erratic operation due to the moment the input draws a large current. Normally, the time starting from the rising point of the incoming current to the limit value of the input current cannot be less than 3 seconds. This feature cannot be inserted after using a timer switch, because after being used it still produces a large current.
Low input current (Low Inrush Current)
In the inlet circuit of the charging machine, there is usually a transformer, coil or capacitance etc., the excitation current or the electric current in the opening line can reach 600 ~ 1000% when operating normally and continuous up to 500ms time, often make the generator unstable or stop the machine, limiting the large and small current of the input current, can improve the stability of the device. Connect a resistor in the input chain to limit the added power, after the transformer is excited or the capacitance is charged, to short-circuit the resistor, which is an effective way to eliminate the electric current. import.
Adjust the charging voltage according to the temperature
When the temperature is high, the voltage of the electricity should be reduced to the right level. The uncontrolled temperature is a malignant circulation, the temperature or voltage of the thermocouple is too high, causing the electric current to be too large, and the electric current is too large to cause a high temperature to produce too much hidrogen, oxygen, This circulation is so severe that it makes the battery too hot and the internal pressure is too large and explosive. Characteristics of each battery are different, the voltage value must be adjusted differently, it is recommended to install after careful study, to avoid producing the opposite effect.
Technically progressive battery manufacturing progress, Valve Regulated form of traditional Vent replaced gradually. The Valve Regulated form has the following main properties:
Gas hidrogen and recombinant oxygen and safety valve
During the battery charging process, because the charging capacity is not 100%, part of the electricity will be dissolved and produce hidrogen and oxygen gas, this phenomenon is particularly obvious when charging too much. or the temperature is too high. Even if hidrogen and oxygen are airborne, the water in the bottle will gradually dry out of use, so periodic water is required, to keep the battery normal.
Valve Regulated battery type is specially designed, under normal charging and charging voltage, hidrogen and oxygen gas can be combined to return to water, recirculating like that, battery characteristics will be is kept unchanged. But if the charging voltage is too high, the rate of gas production rate is higher than the rate of recombination, the internal will be full of gas, the pressure of increase will have a worry of explosion.
To avoid producing high pressure due to unusual voltage or unusual temperature, make the battery become an explosive bomb, so the lid on the battery has a pressure relief valve “indicating not coming in” when The pressure is greater than the set value, the pressure relief valve opens, when the pressure is discharged, the exhaust valve is double after reducing the pressure, how to cool the outside air to avoid the oxidized plate. But don’t forget that the discharged ones are hidrogen and oxygen combined into water, if you often discharge the internal water, the battery also consumes quickly, the capacity drops very quickly, so the voltage is accurately charged. and moderate water temperature is the best way to preserve the battery. In addition to pressure relief, the pressure relief valve also has the function of preventing fire, when the external battery of the battery is burnt, the flame is silenced by the internal exhaust valve, the fire does not reach the internal of the battery to burning hidrogen in the bottle that explodes; There are several factories that add Catalyst internal content, to increase the efficiency of recombination of hidrogen and oxygen, extending the life of the battery.
The main version is usually Paste or Tubular format. The former is mostly American, Japanese and domestic products, the latter is usually European. The internal resistance of the Paste format is small, able to radiate a large electric current, the Tubular form has a strong ability to generate electricity for a long time and is quite long.
Gelled or Absorbed form electrolyte solution
Electrolyte solution of the previous type is nylon fiber stabilized, and the electrolyte solution of the following form is mixed into a lake, the electrolyte solution of the two forms are non-portable, so after being designed In particular, the battery can be assembled in straight or flat form, this not only saves the assembly space, but also can bring many facilities for the operation. The form of long-term attraction will produce a “stratification” phenomenon, which means that the sulfuric acid is quiet at the bottom, forming a slightly higher proportion of the lower part, the lower the density, the lower this situation. will affect a little for the ability to discharge electricity.
Battery tray and battery cover
To prevent further damage when the engine room is on fire, the battery tray material and battery cover must be non-flammable material, and the oxygen level (LOI) index, should be above 28 The meaning of LOI 28 is that the material will burn when the oxygen content is over 28%, so it cannot burn in the air.
The above content focuses on lead storage battery battery, if the battery’s working environment is too high temperature, it is easy to aging so each increase to 80C, the life of the battery ead storage battery will reduce by 1/2, nickel cadmium nickel batteries will only drop by a quarter, if using cadmium nickel batteries will have a longer life benefit.
The function of the converter is mainly a device that sends DC current through vibration control, to produce alternating current, with the main characteristics being:
When alternating current has two sources, to ensure switching between two sources without power outage, two power sources must be synchronized. When synchronous, the phase difference between the two currents must be within 50, the frequency difference must be within 0.3Hz, the voltage difference within 10%. But we cannot understand it because of the changing city power, so we can control the output of the converter to monitor the city power. The city power source will change within a reasonable range, the output of the converter will also change.
At the beginning of the input, the load of the motor, the transformer has a relatively high input current, such as many types of loads, as well as making the electricity, electric current more and more positive, the current flowing in but gradually decreases. The motor’s speed and voltage are built in the transformer, but only in some cycles (Cycle), the transducer must be able to handle overloads in a short time, not to the point of not being enough bear to move to the side of the city. Due to the storage device with moving inertia, the dynamic form is capable of withstanding super strong load. Usually super load capacity is 140% maintain 30 seconds, 125% maintain 5 minutes.
Wide working voltage range
The input power of the converter is DC current, if for example using 180 lead storage batteries, there is a Valve Regulated valve, the voltage when charging is about 2.4V / Cell, the maximum level of voltage Working is 2.4 × 180 = 432V, when power is 30 minutes, the voltage is low to 1.67v / Cell, between 301V ~ 432V, the converter is working normally. Due to the wide working voltage range, battery capacity is maximized, saving for battery investment. But it should be noted that the battery voltage should not be lower than 1.67V / Cell, so as to avoid over discharging batteries that fail.
The brand, the type of UPS very much, the price is different, for example, net type, after choosing a brand, should think whether the equipment is suitable for use or not to adjust appropriately. For example, 30-minute batteries (lead acid, 8-year life span) cost 1/3 of the system, if choosing a battery with a 2-3 year lifespan, the price will naturally drop much; If there is a N + 1 generator, the battery can shorten the time by 5 – 10 minutes, of course saving the cost.
The net type UPS only has a disruption of about 4ms when switching power satisfies the needs of conventional equipment, the MTBF is as high as 70,000 hours; Dynamic type UPS can not break electricity, simple reconstruction, low maintenance work, MTBF up to 200,000 hours, suitable for high-end computer industry or chip production, so there is a use many scientific and technical research areas.
Mixed UPS has battery and converter devices, when the outage of the city can provide reliable high altitude. Dynamic battery batteries without batteries only have storage devices that only last a few seconds.
In the city with low land and high prices, occupying a large area is also one of the cost issues for business. Purely thread and mixed form due to battery, should occupy a larger area. The dynamic form, although there is no battery, and the motor volume is also smaller than the battery, but it is necessary to think about noise, heat and exhaust when operating the motor which affects the surrounding environment.
The efficiency and capacity of the net form is only one proportion, in the range of 83% ~ 93%, in the circuit of the external dynamic form with dynamic barrier, there are no other power conversion components, so the efficiency Very high: in the mixed form, there is the electric motion of the electrical device, the efficiency is secondary. When purchasing a machine of course, it is not possible to set performance as the only option, but high performance will save a lot of electricity costs, for example 500KVA / 400KW, if the distance is 4%, then 400KWx4% x24Hx365 days x 2.5 VND / KW = 350,400 VND / year, can not be said is not large.
In addition, when calculating efficiency, it is also advisable to consider the relevant conditions, for example in the full-force form, to ensure that the motor is propelled smoothly to bear the load, the lubricant and cooling water must always be kept Appropriate temperature and circulation, no less electricity, and increased power consumption due to load-bearing for air conditioners should also be included in it.
When it is necessary to use a combined isolation transformer, since this transformer is a no-load device, it is most appropriate to use a non-crystalline transformer , which is worth about 1.6 times of the molded form but The lowest loss of iron saves electricity and air conditioning money, can recover capital within 3 ~ 5 years.
As a rule, having electricity supplied by the city, adding generators, and UPS can provide a reliable current, especially the MTBF of the dynamic form so high that several hundred thousand hours, but still hard to avoid from trouble. Still not enough for absolutely unbreakable equipment such as information, health, military, finance.
During power saving, the UPS is the subject, if multiple Redundant UPSs are used, it can provide a high utilization rate of 99.9999%. Paired UPS has two types, one is a double link, the output power of several UPS units is connected together, the monitoring of any machine does not affect the power output and capacity, can be used. Full capacity of UPS: but the disadvantage is that there is a malfunctioning machine, potentially causing the system to hang on the whole system. Another type is double isolation, the output source of several separate connected UPSs in their load-bearing units, in addition to a hot-state machine, any one malfunctioned, its load-bearing team will switch Switch to the UPS heater, does not affect the stability of the system: the shortcoming is that the capacity between UPS cannot be shared with each other, low utilization rate and if there is a problem, there will be no unit serial, load-bearing nest must be suspended.
The market is flooded with a lot of UPS, pure forms and dynamic forms have its characteristics, but which one is good, depending on the choice of demand, this document cannot be fully introduced only a few type with typical characteristics, if you want to know the details, you must refer to the technical materials of each product. If you want to buy a good, suitable product for your use, please consider the following conditions:
Noise, interference, energy, certainty, space, investment costs, performance, use, and confidence will achieve your aspirations.