Inverters-Your unswerving getaway from obscurity to luminosityBuying Guides in Inverters

Inverter-Your Best Buddy during Power Outages

An inverter is primarily a device (or should we say a life-saver!) that converts Direct Current (DC) into Alternating Current (AC), and given the recurrent and long power outages experienced mainly by city-dwellers, an inverter remains a must-have gadget in contemporary homes and offices. For the uninitiated, Direct Current (DC) flows from the positive electrical pole to the negative electrical pole in a fluid manner, whilst Alternating Current (AC) moves to and fro between the poles.

Since most of the natural electrical circuits are DC circuits, the inverter is essentially required to convert this Direct Current into Alternating Current that is required by several electrical appliances. This wonder device supports a multitude of home and office appliances, such as televisions, MP3 players, microwave ovens, ceiling fans, CFL bulbs, tube lights, computers, printers, and some specialised inverter variants (known as power inverters) can also be fitted into cars to run a host of devices such as laptops, tablets, car monitors, portable DVD players, gaming consoles, portable camping lights etc.

Understanding the Mechanism

The working of an inverter is no rocket science, rather it is fairly simple. The fundamental parameter in its functioning remains the wave output. Wave output relates to the movement of electrical signals across an oscilloscope, and the physical description of the wave is really significant. Most of the current inverter models use sine wave output.

The inverter functions primarily through a transformer, wherein a primary winding is linked to a secondary circuit, and the centre tap of the primary winding connects the DC power to the transformer. A switch swings to and fro to allow the current to follow alternating paths from one end of the primary winding to the other. This alternating mode of current flow results in alternating current (AC). An electromagnet is used to keep the switch swinging to and fro. In fact, a few of the car power inverters/ inverters employed in power tools make use of the smart Soft Start Technology (SST) that ensures a gradually ascending voltage and prevents an abrupt start of the appliance.

Distinctive Features Found in Contemporary Inverters

Ground Fault Protection: Inverters boasting of inbuilt Ground Fault Protection are ideal for powering portable electrical devices, especially those used outdoors. Ground fault protection is a unique feature that instantaneously turns off the inverter on detection on damp/wet surface, thus impeding any potential threats of fire/electrical shocks. Such inverters subsequently reset, sense the ambient conditions and get back into action mode once the problem has been rectified. With inverters sporting Ground Fault Protection, using your blender, toaster as well as your digital boom-box on al fresco picnics is a cinch! Moreover, you can turn your outing into great fun by brewing your favourite cuppa using your coffeemaker! What's more, you can plug in devices like a digital movie camera to capture beautiful moments into everlasting memories and not be stranded due to battery drainage.

Transfer Switch: A few first-rate inverter models have a built-in transfer switch for seamless swapping between inverter power and utility power (whenever available). The transfer switch allows automatic transfer of external power to the requisite appliances. Characteristically, this feature is pertinent to some truly swish and expensive inverter variants.

Solar Power Support: An inverter also happens to be an integral part of a solar power system. It converts the DC power generated by solar panels and stored in 12V batteries to 230V AC power- ideal for domestic and commercial use. Such inverter units are somewhat expensive due to the extra equipment and electrical work involved in aligning the system with a household's existing electrical set-up.

Battery Basics

A steadfast and fully charged battery is your inverter's best ally. A hefty load is bound to drain a feeble battery and leave you high and dry! Hence, apart from selecting the best inverter, it is imperative to get your battery basics right. To ensure a hassle-free and adroit operation of the inverter, users are advised to always keep the batteries in an impeccable condition. Timely replacement of worn-out, weary and weak batteries is of paramount significance in the general upkeep of the inverter and helps mitigating the overall maintenance costs considerably.

As a matter of fact, a majority of the inverters are powered by a 12 Volt/ 24 Volt battery. Also, some inverters require more than one battery to be wired in parallel configuration. Akin to all batteries, inverter batteries also require periodic recharging, and such batteries can be recharged in numerous ways- by activating solar panels, using a gas generator, or using an automobile engine. Characteristically, good battery maintenance goes a long way in prolonging the life of the inverter.

Vital Deliberations before Buying

If you are a discerning buyer, who believes in meticulous spadework before finalising your purchase, here is a quick low down on the important considerations that shall abet in your buying decision:

Type of Inverter

There are mainly the following two types of inverters available in the market (distinct from each other by virtue of the properties of the waveform generated when the inverter converts DC into AC):

Pure Sine Wave Inverters: Although on the higher side of the price band, Pure Sine Wave inverters, when combined with an upscale switching circuitry, work like a dream in lending power to a horde of home appliances. Such inverters are pretty versatile and remain ideal for powering appliances such as toasters and heaters. In fact, Pure Sine Wave inverters can also be effortlessly used with electronic timing devices, medical equipment, induction motors, delicate scientific research apparatuses, sensitive devices such as laptops, and professional audio/video equipment. Additionally, these inverters can power essential office machineries such as laser printers, copiers and fax machines, in addition to digital clocks, and variable speed motors.

Modified Sine Wave Inverters: Modified Sine Wave inverters may be termed as budget inverters, as they remain a very cost effective alternative when compared to their premium sibling-the Pure Sine Wave Inverters. Although, these inverters sport a small form factor, they deliver a highly efficient performance. Such inverters are ideal for devices boasting of built-in power adaptors such as laptops and chargers.

Capacity of the Inverter

Users must be discrete enough to cherry-pick an inverter size befitting their individual requirement. The choice would depend primarily on the wattage of the devices end-users aim to connect to the inverter, in addition to the maximum number of devices they wish to connect to the inverter at any given point. The important point to bear in mind here is that the inverter must be robust enough to support the collective wattage of all the devices so considered. In fact, it is always advisable to make certain the inverter you have zeroed-in on is sturdy enough to endure the likely strain placed upon it. Employing a small inverter to run equipment that requires steady and substantial power will make running multiple accessories a tricky affair, as most inverters have fuses that will always trip when a certain voltage benchmark is exceeded. To determine the ideal capacity, the user should add up the maximum voltage for each accessory he or she plans to run simultaneously on the inverter, and subsequently add 10% to that number. An inverter that can handle this voltage efficaciously should work uninterruptedly, without tripping the fuse while connected appliances are running. An excellent practice would be to always use an inverter that is rated high enough for the device(s) you are running. At the other end of the spectrum, while there are loads of high-priced and premium variants of inverters available in the market, users must not feel tempted to buy a high-end expensive unit boasting of superfluous bells and whistles, if their individual requirements are fairly simple.

Rating of the Inverter Wattage

An inverter wattage rating is a crucial factor determining its performance, and is usually of the following two types:

Peak Load Rating: Peak Load Rating is the maximum wattage offered for the time required to kick start an appliance.

Top Continuous Load Rating: Top Continuous Load rating is the top wattage available for an extended duration of time. By and large, an inverter offering Peak Load Rating remains the preferred choice for the simple reason that these variants proffer a protracted life and super-consistent performance.

Size of the Battery

A sturdy and adequate battery remains at the kernel of great inverter performance. Hence, no inverter purchase can be contemplated in isolation without paying heed to battery specifications. Commonly, the battery size can be accurately ascertained based on the anticipated runtime and the wattage load. An incompatible or inadequate battery configuration may not let the inverter power up. Also, the deficiency may lead to the battery discharging quite frequently, leading to permanent battery damage.

In order to avoid any battery-inverter mismatch issues and to acquire a reasonable idea of the apt battery size, buyers may employ the following formula to ascertain the right battery configuration:

Inverter Rating in Watts Input Voltage x Usage time (in hrs) = Battery size

For instance, 600W (Inverter Rating) 12V (Input Voltage) x 5 hours (Usage Time) = 250 Amp (Battery Size)

Some Quick Formulae for Reference

Novices geared up for their maiden inverter purchase may refer to the following list of formulae to further simplify the complex technical attributes associated with an inverter:

Formula to convert Amps into Watts

Amps X 120 (AC voltage) = Watts The result so arrived at gives you a sketchy outline of wattage required for continuous load of the device in question.

Formula to calculate Approximate Start-up Load

Watts X 2 = Starting Load

The result thus derived is an approximate figure of wattage required for starting load of devices. However, some of the devices being considered might need additional starting load. For instance, heavy-duty appliances such as air conditioners and refrigerators may require a start up surge of 3-7 times the continuous rating.

Formula to convert AC Watts to DC Amps

AC Watts divided by 12 x 1.1 = DC Amps

Formula to Calculate Continuous Rating

Maximum combined wattage + 20%

Miscellaneous Factors

Apart from the primary considerations mentioned above, other sundry parameter astute buyers must pay attention to while buying an inverter are the after sales service offered by the manufacturer, and the type and tenure of warranty offered by the company. Consumers must note that some makers offer extended warranty over and above the standard warranty for an extra fee. Therefore, buyers must scrupulously research these offerings across major competing brands before actually coughing up their hard-earned money towards the purchase of an inverter.

Key Brands

Given below are some of the popular brands of inverters that consumers can choose from:

  • Microtek
  • Luminous
  • Sukam
  • Videocon


Make a Rational Buying Decision

An inverter is no longer a superfluous luxury, but remains a basic necessity given the times that we live in. It is an indispensable device-engineered exclusively to deliver truly augmented expediency in using electrical appliances, even when the power supply is absent or available at an extremely low voltage. Perceptive buyers may use the above exhaustive guidelines to make a truly informed buying decision and empower themselves with the best inverter aptly befitting their distinctive prerequisites.