Single Phase vs Three Phase UPS

Single Phase

How do I choose the right UPS for the job?

To ensure that you always end up with the right UPS for your needs, be sure to consider these eight issues during your selection process:


Question number one is should you get a single-conversion, double-conversion or multi-mode UPS? The answer depends largely on how important energy efficiency is for your organization relative to protection. Single-conversion UPSs are more efficient than double-conversion devices, but offer less protection.

That makes them a good fit for loads with a higher tolerance for failure.

More specifically, standby UPSs (the most basic type of single conversion UPS) are generally the best option for smaller applications, like desktop and point-of-sale solutions, while line-interactive UPSs are typically preferable for smaller server, storage and network applications located in facilities with access to relatively trouble-free AC utility power.

Double-conversion UPSs, which provide the highest levels of protection, are less efficient but are usually the standard choice for protecting mission-critical systems. Multi-mode UPSs, although they may be more expensive than either single or double conversion systems, are the best choice for companies looking to achieve an optimal blend of both efficiency and protection.

Single phase versus three phase

When the utility generates power, it is at the three-phase level. This type of power is available to almost all commercial and industrial customers, as they are typically large consumers of power. Three-phase power uses three separate “phase” wires, which allow higher power to be delivered to a single point or load.

Most homeowners only have single-phase power available to them, as homes are typically small power users. Single-phase power is delivered through either one or two phase wires, which are derived from the utility three-phase power system using transformers.

Single phase UPSs tend to be a sensible and economical option for simpler, smaller applications with low kVA requirements, which are typically seen in the home, small businesses and in remote or satellite offices where computing power is less than 20,000 VA.

Three-phase UPSs are generally the preferred choice for high kVA applications, which are typically more sophisticated and have high compute densities. Large multistory buildings, data centers and industrial facilities protecting high-power processes are typical three-phase UPS customers, as they need to distribute large amounts of power over relatively long distances.