Uninterruptible Power Supply (UPS)

What Is an Uninterruptible Power Supply (UPS)

An UPS is a device that supplies power to connected devices for a certain period of time in the event of a power failure due to a power failure.

It has a built-in battery and supplies power to servers, PC electronic equipment, network equipment, etc. in the event of power failure or power supply trouble, for example.

Uses for UPS

UPS are used in a variety of locations to provide appropriate countermeasures on the power demand side in the event of power outages due to power transmission route malfunctions or natural disasters, or power supply fluctuations due to power supply changes caused by large-scale construction projects, etc.

Power interruptions can be delayed for several minutes so that equipment can be processed for normal termination during this time to avoid malfunctions.

In offices, it is used for PCs, OA equipment, network equipment, etc., and in stores, for POS terminals, customer information terminals, crime prevention, disaster prevention equipment, etc. In call centers and data centers, they are used for PCs, servers, communication equipment, and air conditioning equipment. In the financial sector, they are used in ATM terminals and online terminals, and in broadcasting stations, they are used in broadcasting equipment and electrical equipment. UPS are used in a variety of fields to protect power supplies and ensure stable operation.

Depending on the model, UPS can be combined with power management software to automatically and safely shut down or start up equipment in the event of a power failure.

Principle of UPS

UPS generally consists of the following circuits and batteries:

• Converter
  A circuit for converting AC power to DC power.
• Inverter
  A circuit for converting DC power to AC power.
• Bypass
  A circuit for outputting AC power directly.
• Switch
  Circuit to switch between inverter output and bypass output.

UPS are available in a variety of power supply methods, the three most common of which are as follows:

1. Constant Inverter Power Supply System

This is a method in which power is supplied through an inverter regardless of the state of the commercial power supply. Power is supplied by the inverter in both normal and blackout conditions. It is possible to supply stable power at all times while eliminating noise. 

2. Line Interactive Method

During normal operation, power is supplied from commercial power and at the same time the battery is charged via an inverter. In the event of a power failure, the system switches to inverter power supply, but since power is still supplied to the inverter during normal operation, the switching time is shorter than that of the continuous commercial power supply system. 

3. Constant Commercial Power Supply System

This system supplies power directly from the commercial power source during normal operation and switches to inverter power supply from the battery during a power failure. Since the inverter is stopped during normal operation, this is a power-saving system, and since it uses fewer circuits, it has the advantage of being compact and inexpensive. On the other hand, it is not suitable for connection to equipment that requires stability because a momentary power loss of several milliseconds may occur when switching the power supply.

Other Information on UPS

1. Service Life of UPS

UPS has a relatively long and useful lifespan, and generally need to be replaced after about 5 to 6 years; since UPS are constantly energized, the electrolytic capacitors inside them are prone to failure, and it is recommended that long-term use beyond their useful life be avoided.

It is important not to use UPS past their standard service life, as they may catch fire due to deterioration over time. In addition, periodic inspections are necessary, as use in environments with high temperatures will shorten the service life of the unit.

2.The Battery of the UPS

UPS are equipped with batteries inside to supply power to connected devices in the event of a power outage.

There are two types of batteries for UPS: MSE and UPS-only.

The charge capacity of a battery decreases as it is used. It is recommended that they be replaced when their charge capacity drops below 80%. Many models are equipped with an LED lamp to indicate battery deterioration. Battery replacement can be done without specialized knowledge.