How Do UPS Systems Differ?

How Do UPS Systems Differ?

The three basic uninterruptible power supply (UPS) technologies can be used to protect today’s distributed IT infrastructure, especially on the edge. There are advantages to each technology, and they may all be necessary when configuring cost-effective power protection, especially in complex systems. There are a number of factors to consider when selecting a Whole house UPS for your particular application. For choosing a UPS for power backup, it is important to consider the load size, location, and criticality of the equipment to be protected, as well as the budget.

A UPS system can be configured as online double conversion, line-interactive, or offline (also known as standby or battery backup). These UPS systems differ based on the way power is exchanged.

Double Conversion Online

A generator of AC power produces clean, stable power. It may, however, experience voltage sags, spikes, or total failure during transmission and distribution, causing computer malfunctions, data loss, and equipment damage. Among all the power problems encountered by IT loads, only online double conversion technology provides comprehensive protection against all of them, providing the highest levels of security for networks.

A UPS system that works online is called a double conversion system since the incoming power is converted to direct current (DC) and then converted back to alternating current (AC). AC-DC/DC-AC design ensures greater isolation of the load from irregularities on the main supply.

Using a rectifier, the online UPS converts the incoming AC power supply into DC to charge the battery and run the connected load via the inverter without the need for power transfer switches. When the main AC input fails, the rectifier drops out of the circuit, and the batteries keep the devices connected to the UPS powered. In the event of restoration of AC input power, the rectifier resumes carrying most of the load and charges the batteries.


UPS systems with line-interactive battery backup provide both power conditioning and battery backup. In areas with frequent power fluctuations and few outages, this technology is particularly effective. Unlike battery backup systems, line-interactive UPS systems can handle a wide range of input voltage fluctuations.

Emergency power & UPS systems - Turn Key Systems - Zeppelin Power Systems

The line-interactive UPS provides far better control over power fluctuations than offline UPS systems. Line-interactive UPS have the advantage that they accept a range of input voltages and they have voltage boost circuitry. In other words, the greater the range, the more protection you will get.

Battery Backup/Standby/Offline

An offline UPS, also known as a battery backup or standby UPS, is a cost-effective option. The best offline UPS systems switch to battery fast enough to prevent power anomalies and handle short outages. A UPS that is offline protects against most spikes, but does not maintain perfect power during minor fluctuations.

The key to offline UPS quality is the range of power the unit will accept before switching to battery backup. The wider the range, the less battery drain there is, and the longer the backup time is when the power goes out. A UPS that switches to battery backup more often will have a shorter battery life.

The offline UPS technology will provide protection from most power spikes by clamping down on excess voltage and will help survive more than 90% of all power outages. Utility AC power is fed directly through an offline UPS unit, past a transfer switch, to the output point where the protected load is connected.