What is the Difference Between an Inverter and UPS?

When it comes to the regulation of electrical power, whether for your home or business, there are two devices widely utilized with today’s modern electrical circuitry: the power inverter and the UPS (uninterruptible power supply). The UPS uses an internal inverter, which basically converts DC (direct current) power from its on-board battery to AC (alternating current). The standalone inverter usually connects to an external DC source (such as a car battery) to maintain the flow of AC power from a DC source.

Basic Points about a UPS

• A UPS device comes equipped with a battery that has its own power supply, as well as a way of indicating usage, or need for usage. A UPS resists the drastic fluctuation in the power supply. It contains a surge protector and voltage regulator that regulates the flow of electric current. The UPS stabilizes the main AC power supply when the voltage spikes, and boosts the power supply when the voltage sags. Furthermore, if there is a storm and suddenly the electricity goes out, the UPS can keep delivering AC electricity for some duration of time via its battery. The battery is then charged, once not in use, by the main AC power supply—and so the cycle continues. This device is especially useful for computers and other electronic equipment sensitive to voltage fluctuations.

History and Function

• An inverter is an electrical device for converting DC current into AC current. It was invented in the late nineteenth century when the conversion of DC to AC power was carried out by rotary converters or motor-generators. The inverter has a wide range of applications, from switched mode power supply in computers to large power stations which use direct current for bulk transmission of electrical power. A UPS contains an inverter and battery to supply alternating current when main AC power is unavailable.

Difference Between an Inverter and UPS

• The difference between an inverter and UPS is subtle because their ultimate purpose is identical: converting direct current into alternate current. In addition to, they both need the same electrical components to function properly: a battery unit and an AC-to-DC conversion unit. When the main power fails, both the inverter and the UPS will supply the alternating current from switching the main source to battery source. This switching time varies between inverter and UPS. For example, a standalone inverter normally takes greater than 20 milliseconds to shift from the main source to a backup source, while the switching time for a UPS is less than 10 milliseconds. Thus, the UPS can offer more protection against damage or data loss to computers or other sensitive electrical devices.

  In addition, power inverters typically don't have an integral battery to supply DC power as do UPSes, so an external source of power must be available and connected to an inverter.

The Portable Inverter

• A portable inverter can be easily purchased for around $25 or less, depending on the manufacturer, capacity and features. Basically, the power input side will be plugged into a standard cigarette lighter or power port of a motor vehicle. It is attached to a small box with a power outlet to plug a laptop or any other device that would normally plug into the AC wall outlet of a home. Since the inverter runs using power from the battery, it is advisable not to keep it plugged in without the engine running for very long.

The Portable UPS

• A portable UPS can run from any power source, including those in vehicles, solar panels and batteries. They can be very handy in rural or wilderness areas that do not have access to the main electrical grid. These portable units can be transported in a briefcase-like container, and some even come with solar panels to provide a power source.