When utility power suffers an outage, an uninterruptible power supply (UPS) can provide a continuous electrical current. These units are typically used as a secondary power source for emergencies. Depending upon the type of business and its needs, different types of UPS’s may be more appropriate than others. Below, we’ll describe the 4 main types of UPS’s that are currently available and deployed in various industries throughout the world.
#1 – Offline UPS
Also called a “standby UPS,” this unit doesn’t act until a disruption in the electrical current is identified. After this happens, the battery within the UPS begins supplying the current in the utility’s absence. When the UPS closes the transfer switch and begins to supply power, there’s a brief period during which power is unavailable. While offline UPS’s are inexpensive compared to other UPS solutions, some types of sensitive equipment can’t work properly with this inherent limitation.
#2 – Online UPS
An online UPS maintains a constant connection from the UPS battery to the equipment that needs power. Electricity is converted from AC to DC and then converted back to AC before delivery. The continuous link between the online UPS’s battery and the equipment not only prevents any brief loss of power (like that experienced with offline UPS’s), but helps manage voltage irregularities. While this type of UPS usually costs more and is less energy-efficient, its reliability is an important factor for many mission critical applications.
#3 – Ferro-Resonant UPS
This type of UPS is very similar to an offline UPS. It works in the same manner. The most significant difference is the use of an internal transformer within the ferro-resonant UPS. The main limitation of an offline UPS is the brief power loss between the time the transfer switch is closed and the battery begins supplying power. The ferro-resonant UPS’s transformer is designed to resolve that issue. Ideally, the transformer holds enough energy to cover the momentary power loss. Because equipment that’s used for power factor corrections reacts poorly to the transformers, this type of UPS is seldom used today.
#4 – Line Interactive UPS
Line interactive UPS’s attempt to correct some of the problems of an offline UPS. Like an online UPS, this unit maintains a continuous connection between the battery and the output. However, the primary source of the electrical current is still the AC input. In the event the primary source becomes unavailable, the transfer switch is opened, allowing an inverter and converter to charge the battery before delivering the current. While they’re more expensive than an offline UPS, they still have difficulty regulating voltage sags and surges.
Choosing A UPS Solution
The primary constraint for most small businesses is budgetary. While an online UPS provides consistency and reliability, they’re expensive. However, while an offline UPS is less-expensive, the unit can expose your sensitive digital equipment to unpredictable power outages and surges. Weigh your options and your power needs. Then, try to invest as much as you can afford in a robust UPS solution. While the initial investment can seem prohibitively high, it’s an insurance policy worth having.