An uninterruptible power supply (UPS) is a device that provides a backup power source to critical devices and systems in the event of a power outage or other electrical disturbance. It is designed to keep these devices and systems running smoothly and uninterrupted, even in the case of a power failure. A computer is one of the delicate devices that require a stable source of power.
The most common types of UPS are standby/offline, line-interactive, and double conversion online. All are used to achieve the main function which is to provide a steady flow of clean stable power to the computer. An uninterruptible power supply reduces cases of data loss due power related issues and acts as an alternative source during a blackout.
Functions of the uninterruptible power supply (UPS)
- It regulates power from an unstable power source to the required clean stable voltage for computer use.
- It prevents power surges and brownouts that might destroy the computer.
- It temporarily provides power to the computer in case of the main power failure. This allows the user to save his/her work and shut down the computer using the correct procedure.
- Alerts the user of any power loss (by beeping).
- To ensure that work continues even in the absence of main power. This is mostly implemented in organizations that give important services such as banks, schools, & hospitals.
- UPS helps reduce cases of data loss when the power goes off suddenly. When working on a computer and power goes off, data that was not saved to the secondary storage device is lost. UPS helps the user to save the data and shut down the computer using the right procedure.
- One of the components of an uninterruptible power supply is a battery. UPS manages the battery by charging and discharging it to make sure they are ready when the main power goes.
How uninterruptible power supply (UPS) works
A typical UPS has a battery and inverter and it is connected between the primary power source and the device. When the main power is stable device gets its power directly from the primary source. When the main power is unstable or goes off, it switches to the battery. It uses the inverter to change the current from Direct Current (DC) to Alternating Current (AC) which can be used by the device. When the primary source is stable the UPS charges the battery for later use.
Types of uninterruptible power supply
There are several types of UPS systems, which can be classified based on the type of power they use, their capacity, and the way they provide power to the load.
Offline or Standby UPS: this is the most common type of UPS that are used in most office and home. They are the cheapest type of UPS. In its basic operation when there is power the computer gets it direct from the main source. When the power goes off it gets power from the UPS battery which is converted to AC by the inverter.
It provides short-term power from a battery when the main power goes off. The term standby is adopted since the inverter is not active until the primary power source goes. So the inverter is on standby.
Line-interactive UPS: it is an improved version of offline UPS. In addition to offline capability, it also has a voltage regulation feature that stabilizes voltage. Line UPSes have an internal transformer that deals with voltage spikes without switching to using a battery for the power. The inverter is always active compared to offline which is inactive until the primary source goes off.
Double conversion online UPS: it is an advanced type of UPS that is more expensive than all the other types. The power from the main source is converted from AC/DC then DC/AC hence the term double conversion. This ensures that the power being supplied to the device doesn’t entirely depend on the primary source.
In this UPS the inverter is always active. This type of UPS is used in the area where power is critical since it supplies clean stable power irrespective of an unstable main source.
Components of uninterruptible power supply
UPS Batteries: It acts as the alternative power source when the primary power goes off or it is unstable. The battery is charged when the power is on to be used during emergencies. Depending on the size of the UPS the battery can be internal or housed in a different casing. The period that the battery can last depends on its size and the load connected to it.
Rectifier: when power from the main source gets in it is required to charge the battery. The rectifier converts AC power to DC and also recharges the battery. It then directs the power to the rectifier (for double conversion UPS). On the line-interactive UPS, the rectifier cleans the small voltage spikes to try to stabilize the power.
Inverter: it is used to convert DC from the battery to AC that is directed to the device or load. In the double conversion type rectifier and inverters are used to remove spikes, surges, noise, and other power abnormalities. This provides clean stable power to the load.
Static Switch: it is also known as a static bypass switch. It is used to cater to a situation where the UPS itself is not working. The bypass switch is used to connect the load directly to the primary source in case the UPS malfunctions.
Cooling system (fan): since UPS deals with the power they can overheat. To remove heat from the device most UPS uses a fan to cool down the system.
Power connectors: Uninterrrutiple power supplies have both input power supply connected to the primary source and output connected to the load. Small standby UPSes can have more than one output connector port.
Advantages of Uninterruptible power supply (UPS)
- Provide a stable clean power source to the computer device.
- UPS helps reduce cases of data loss due to power issues.
- They offer an alternative power source to the load.
- UPSes are reliable sources of power for computers or devices connected to them.
- Most of them have an alert system for users to know when the main power source is not working. The more advanced system can have an online monitoring system that can alert users when the power goes off.
- Generally, UPSes are expensive to buy. The bigger and more power required the more expensive it is.
- They require regular maintenance which has an extra cost to the organization.
- For big-size UPS you require extra room for the installation of the whole system.
- UPS as an alternative power source is limited to the size of the battery. The time can range from a few minutes to hours.
- The lifespan of most UPS is limited to the life of batteries that are used. The batteries have a limited functioning time which limits the lifespan of the UPS