What is the difference between a UPS and an inverter?

Electricity is a must for electronic devices to power up and run smoothly. However, even minor fluctuations from a power source can be hazardous to the devices and appliances that rely on it. Although many of us take electricity for granted, to conserve power in certain cities, supplies are cut short for set intervals — or sometimes, for irregular periods.

To protect the internal circuitry of such equipment, a reliable and continuous power supply is necessary and ideal. Fortunately, there are options and batteries are typically the most common.

There are two widely known solutions to battery-based power backup: an uninterruptible power supply (UPS) and an inverter. A UPS typically protects from power surges and only operates when the original power source is lost. An inverter is similar, but serves as the medium between the primary power source and a battery.

Generally, a UPS is preferable for use with computers or related devices while inverters are used with home appliances, such as fans, freezers, televisions, etc.

Now, let’s get into the details and compare the technical and commercial differences between a UPS and an inverter.

1. Making comparisons. The advantage of a UPS is in its efficiency. It’s a fast-acting electric circuit that instantly provides backup power for another device. It ensures a smooth transition so the device, such as a computer, continues to work without fail or damage. An inverter involves circuitry that converts AC to DC, with power from a battery. So, when an appliance loses its original power source, the inverter converts DC power stored in a battery to AC, which it transmits to the appliance. It has a slower response time than the UPS.

2. Working principles: An uninterruptible power supply and an inverter are fairly similar. However, a UPS monitors the necessary input power-voltage level and processes it in terms of voltage regulations. An inverter converts DC power from a battery to fulfill any necessary power requirements. Technically, it works as a go-between the battery and an appliance, relying on relays and sensors to detect when DC power is needed.

3. Changeover time: Changeover time refers to the elapsed time to changeover from one source of operation (or from one device) to another. For example, in this case, it’s the total time that a battery backup system takes up to supply power after the original source of electricity fails. A UPS requires about 10 to 15 milliseconds, so it’s fast. An inverter takes up to 500 microseconds. Although both delays are quite minimal, the choice should be based on the device being protected. For instance, a UPS only provides backup supply for a short duration but it offers a smooth transition, whereas an inverter can do so for an extended period and at a lower cost. An inverter also offers voltage variation, which can be better for certain sensitive appliances.

4. Input power: Comparatively, an inverter has a broader range of input power as compared to a UPS. The inverter uses between 170 to 270V AC while a UPS works at about 240 to 270V AC.

5. Types & circuitry: There are three types of UPSs: offline (which means it’s on standby), online (which uses a double conversion method, where the AC travels through a rectifier), and line-interactive (which can automatically regulate voltage). An inverter can also be divided into three types, based on the type of wave generated: square, quasi, and sine waves.

Perhaps not surprisingly, the circuitry of a UPS is far more sophisticated than that of an inverter as the former offers advanced features and higher protection rates.

6. Voltage fluctuation: While voltage fluctuations in input supply are typically adjusted by the device or appliance that requires the power, it’s always preferable to have smooth output voltages. This is where an uninterruptible power supply excels in comparison to inverters, making the UPS ideal for computers.

7. The cost: A sophisticated circuitry, along with its swift and near-instantaneous operation, means a UPS is more costly than an inverter.

8. Pros & cons: An inverter’s disadvantages are that it has greater fluctuations in power output, greater delays, and simple circuitry. So, inverters are typically used for general electric appliances or gadgets, where operation is only minimally affected by delays in power supply.

A UPS, on the other hand, is more costly. This restricts its widespread use for most larger appliances. But a UPS is ideal for computers, servers, or workstations, which perform critical tasks and that cannot tolerate delays in power supply.

Interestingly, new inverter types such as pure sine waves have reduced fluctuations and delays in output voltages. Since they’re already an economic power backup solution, UPS’s tend to be more redundant and are slowly losing their market share.