How does an Uninterruptible Power Supply (UPS) work?

The full form of UPS is Uninterruptible Power Supply (UPS). It is equipment that helps retain power at power failures. Sudden power failure can lead to switching off devices like computers and network equipment.

The sudden power-off may lead to the loss of essential data and damage to the devices, so the role of UPS is to protect the data and devices. The user can turn off the machines safely. It helps in continuously supplying the power at fluctuations and abrupt power cuts. The UPS is a battery-enabled system that can self-activate during power loss.

Types of UPS

Standby UPS

It is the most basic type of UPS used. It works well at the time of the power failure and voltage surge. The primary function is to deal with voltage fluctuations. If the voltage level goes very high or low, the standby UPS converts the DC power battery into an AC power supply. The most common applications are entry-level computers, security systems, and other electronic devices.

Line-interactive UPS

The line-interactive UPS helps the electronic devices at the time of minor fluctuations. It has an autotransformer that regulates the current at either high voltage or low voltages. Some Of the leading applications are home theater, network equipment, gaming systems, personal computers, etc.

Online Conversions

Online conversions work on the DC power technology. In this technology, the UPS has distinctive DC power, which continuously supplies the electricity, as it is fully attached, so there is no need to switch to DC power. The extensive set generally uses the online conversion UPS. Some examples are high-end servers and large data center installations.

Ferroresonant UPS

The way of operation is similar to the line-interactive UPS. The main point of differentiation is that these UPSs use the ferroresonant to supply the power for a long time. The user can get sufficient time to switch on the line power until then. It assists in no-break transfer. The primary area of applications is heavy industry markets like oil and chemicals.

Multi-mode UPS

These UPSs work in premium power protection mode and eco mode. The multi-mode UPS is designed to switch between the modes as per the requirement.

UPS Components

  • Charger – as with the other electrical gadgets, the UPS needs the charger to charge the battery to supply uninterrupted power.
  • Battery – It offers sufficient power back-up to work smoothly even during prolonged power failure.
  • Inverter – It is one of the significant components that supply electricity.
  • Static Switch – The inverter is attached to the status switch that transfers the load to the inverter and then back to the inverter.

Modes of Operations


The inverter is connected to the mains. The inverter delivers the load through the static switch. But in case of power failures, the inverter will disrupt the main supply. At this stage, the inverter will use the internal oscillator to ensure a smooth electricity supply.

Loss of input power

At power failure, the DC power needs time to reach the threshold and resume its provisions. For some time, the inverter will operate on the battery so that the AC power has time to come to its normal functioning and the DC power can reach its low threshold. During the entire process, the electricity connection is not disrupted, and it helps in better recharge of the battery.

Bypass Operation

Under the bypass operation, the inverter consists of a sensing circuit that can sense the unusual current or voltage flow. The sensing circuit can transfer the critical load to the static bypass without the interruption of the load. The role of the bypass logic is to again transfer the current to the alternate line without a break.

Functions of UPS

Power-off protection

The purpose of the UPS is to supply uninterrupted power to avoid the inconvenience caused to the users. The UPS can quickly convert the DC power to AC power.

Voltage Protection

Either very high voltage or very low voltage can damage the equipment. The UPS controls the power supply and keeps the power supply.

Harmonic Distortion protection

The power is supplied through the transmission lines, and sometimes these lines have voltage distortions. The UPS can protect these lines from harmonic distortions.

Instant Protection

Sudden power loss is fatal for electrical equipment, leading to huge losses. The user can install the UPS and curb the losses to deal with these losses.

Extends service life

It offers various advantages like normal functioning, better service life, and reduction in noise that ensures better efficiency.

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