1. Concept

UPS stands for the English phrase: Uninterruptible Power Supply is understood as an uninterruptible power supply system or simply a backup power storage unit to increase the reliability of the system’s power supply. Small UPS systems provide power in minutes; enough to power down the computer in an orderly fashion, while larger systems have enough battery power for several hours. In mission-critical data centers, the UPS system is only used for a few minutes until a generator takes over.

A UPS is more than just a battery as it also provides power conditioning for additional protection against problems such as voltage spikes. The UPS uses active filters to eliminate harmonic distortions to produce clear, consistent AC waveforms.

2. Utilities of UPS

Applications of the UPS equipment range are based on the design and quality of the equipment. They are suitable for many situations from everyday to professional. Certain normal operating conditions require a high-quality power supply for sensitive electrical loads in industrial applications or even in extreme situations. Some typical cases include:

  • General daily power backup for office and home systems, simple and environmentally friendly.
  • Industrial and process-sensitive applications require the UPS to provide seamless, three-phase, high-capacity power.
  • Medical centers and emergency facilities need UPSs to provide clean and reliable power to critical life-saving equipment.
  • Data centers and critical telecommunications facilities need backup for highly sensitive and highly loaded electronics.
  • Sturdy and military-grade applications need protection from moisture, altitude, shock and vibration, and dust.

3. How UPS Works

Before you know how a UPS works, you need to know what’s in the UPS system. Below are the components of the UPS.

  • Rectifier or charger: generates DC power to charge the battery or possibly to power the inverter.
  • Inverter: produces quality electrical power and is free from interference from all utility power sources.
  • Battery : provides enough backup time to ensure device safety.
  • Static switch: a semiconductor device that transfers the load from the inverter to the utility and back again.

4. Main UPS Series

UPS devices cover many use cases, but their topologies or types come in three basic configurations:

  • Standby UPS or Offline UPS

When there is power to the grid, the UPS will deliver electricity directly to the load. When the power fails, the load will be switched to supply power from the battery to the inverter. The scope of application of this type of UPS is usually for simple equipment, small capacity, less sensitive to the grid, requiring low reliability. Most UPSs today have software included that communicates with the computer via COM or USB ports. This software allows to control the operating status of the UPS (I/O voltage, load consumption…). In addition, one can also set up the schedule automatically. There are UPS types such as rolling door UPS, in automatic parking management system, .. The main advantage is compact, easy to operate and repair.

In principle, the inverter is connected in parallel with the AC input in the standby state. In normal operation, the load is supplied by the power supply through filters that remove certain disturbances. The inverter operates in passive standby mode.

  • Line Interactive

On-line interactive UPSs work like a backup UPS, but with the addition of a power regulator to regulate the input voltage to a normal level before going through sensitive equipment. In directly interacting devices, if the power goes beyond a predefined specified limit, the battery takes over.

In principle, the inverter is connected in parallel with the AC input in the standby state and charging the battery. In normal operation, the load will be supplied with a stable power supply through the parallel connection between the AC input and the inverter.

The inverter works to provide voltage conditioning or battery charging. The output frequency depends on the AC input frequency.

  • UPS Online

Works on the principle of double conversion: from AC to DC then back to DC to AC. Therefore, the power supply to the load is completely generated by the UPS, ensuring stability in both voltage and frequency. This makes the equipment powered by the UPS virtually completely isolated from changes in the grid. Therefore, the source generated by the online UPS is a clean power source (filtering most problems on the grid), completely anti-interference. The output voltage is completely SIN shape and the switching time is almost zero.

In principle, the inverter is connected in series between the AC input and the AC branch input. In normal operation, all power supplied to the load will go through the charger and inverter, and perform double conversion like AC to DC to AC.

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