What is an Uninterruptible Power Supply?

What is an Uninterruptible Power Supply?

Uninterruptible power supply definition

An uninterruptible power supply is a device capable of providing a continuous power supply with the primary purpose of protecting critical loads from grid outages, voltage fluctuations, frequency changes, and other power quality issues.

The basic components of uninterruptible power supply:

• Battery pack: provides backup power to the UPS. When the mains power fails, the battery pack can supply power to the load.

• Charger: When the mains is normal, the charger charges the battery pack.

• Inverter: Converts direct current (DC) to alternating current (AC) to power the load.

• Static bypass switch: When the inverter is faulty or in maintenance, the static bypass switch can switch the load from the inverter to the direct mains power supply.

• Automatic bypass switch: During inverter failure or maintenance, the automatic bypass switch ensures that the load still receives a stable power supply.

• Monitoring and control system: Monitors the status of the UPS and controls its operating mode.

Working principle

When the mains is normal, the UPS will supply the mains voltage to the load after voltage regulation. At this time, the UPS is an AC mains voltage regulator, and it also charges the battery in the machine.

When the mains supply is interrupted (accidental power failure), the UPS immediately supplies 220V AC power to the load by switching over and converting the inverter to keep the load working normally and protect the software and hardware of the load from damage.

Uninterruptible power supply classification

According to the working principle, it is divided into: backup, online, online interactive.

• Backup UPS: When the mains is normal, the mains directly supplies power to loads. The UPS starts the inverter only when the mains is abnormal.

• Online UPS: Regardless of whether the mains power is normal, the inverter is always in the working state, converting the direct current to alternating current to power the load, and the mains power is only used as a charging power source.

• Online interactive UPS: combines the characteristics of backup and online, when the mains is normal, the inverter is in a hot backup state, when the mains is abnormal, the inverter quickly starts to supply power to the load.

It is divided into small UPS, medium UPS, and large UPS by capacity.

• Small UPS: the power is generally less than 1kVA, suitable for personal computers, small office equipment and so on.

• Medium-sized UPS: The power is generally between 1kVA-10kVA, suitable for small servers, network equipment, etc.

• Large UPS: the power is generally more than 10kVA, suitable for large data centers, communication hubs, etc.

Advantage

• Provide uninterruptible power supply: When the mains is interrupted, it can immediately provide a stable power supply for the load to ensure the normal operation of the device.

• Voltage regulator function: It can regulate the voltage of the mains to protect the load from the influence of voltage fluctuations.

• Clean power supply: It can filter the clutter and interference in the mains to provide a pure power supply for the load.

• Easy to manage: usually equipped with intelligent management system, can achieve remote monitoring, fault diagnosis and other functions, convenient management and maintenance.

Shortcoming

• Higher cost: Compared with ordinary power supply equipment, the price of UPS is higher, which increases the investment cost of users.

• Complex maintenance: The UPS requires regular maintenance, such as battery replacement and inverter check.

• Energy consumption: UPS consumes a certain amount of electricity during operation, reducing energy efficiency.

Apply

• Computer system

• Communication equipment

• Medical equipment

• Industrial automation