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4 types of uninterruptible power supplies

uninterruptible power supplies

In the event of a power failure, an uninterruptible power supply (UPS) system can provide continuous power. These devices are typically used as secondary power in emergency situations. Depending on the type of business and its needs, different types of UPSs may be more suitable than others. Here are the 4 main types of UPS currently available and used in various industries around the world.

Stand-alone UPS

Also known as a “standby UPS”, this device does not work until a power failure is detected. The battery inside the UPS then begins to provide power when there is no mains power. When the UPS closes the switch and starts supplying power, no power is available for a short time. Although offline UPSs are inexpensive compared to other UPSs, some types of sensitive equipment may not function properly under this limitation.

Online UPS

An online UPS (uninterruptible power supply) maintains a constant connection between the UPS battery and the equipment that needs power. The current is converted from AC to DC and back to AC before being powered. The permanent connection between the inverter battery and the equipment not only avoids short-term power outages (as with stand-alone inverters) but also manages voltage fluctuations. Although this type of uninterruptible power supply (UPS) tends to be more expensive and less energy efficient, its reliability is an important factor for many critical applications.

Ferro-resonant inverter

This type of inverter is very similar to a stand-alone inverter. It works in the same way. The main difference is the use of an internal transformer in a ferro-resonant inverter. The main limitation of the offline inverter is the momentary loss of power between the closing of the circuit breaker and the energizing of the battery. The ferroresonant transformer UPS is designed to solve this problem. Ideally, the transformer contains enough energy to cover the short-term power loss. Since the devices used for power factor correction do not respond well to transformers, this type of uninterruptible power supply (UPS) is rarely used today.

In-line Interactive Inverter

Inline interactive inverters attempt to solve some of the problems of offline inverters. Like an online uninterruptible power supply (UPS), this device maintains a constant connection between the battery and the output. However, the primary power source is still the AC input. If the main power source fails, a switch opens to allow the inverter and AC to charge the battery before supplying power. Although these UPSs are more expensive than stand-alone UPSs, they can hardly cope with voltage drops and surges.

Choosing a UPS solution

The biggest constraint for most small businesses is budget. Online UPSs offer consistency and reliability, but they are expensive. Offline UPSs are less expensive, but they can expose sensitive digital equipment to unpredictable outages and power surges. Evaluate your capacity and power requirements. Then try to invest as much as possible in a reliable uninterruptible power supply (UPS). While the initial investment may seem exorbitant, it is worth the insurance.

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