HOW THEY WORK : “How the Power Inverter Works” (Cont’d)

In the previous article, we looked at the two very important states of electric current, namely, AC (Alternating Current) and the DC (Direct Current). These two terminologies are the basis of our main subject matter, the inverter and its close associate, the battery charger. When I talk of a charger, a battery charger for that matter, many of you may have seen or owned a mobile phone, this device works off the power saved on its battery, this battery has to be charged periodically. A charger is the device that converts the mains power (ELECTROGAZ) to such that, it is stored in a portable form on your battery. It would have been such a bother to keep plugging and unplugging the phone as and when you desired. Likewise, most portable devices like Laptop computers come complete with a battery charger and an imbedded form of an inverter. It is these inverters that convert the direct current (DC) into a workable alternating current (AC). Why do I call the AC a workable current or power? This because, it has a frequency and is easily transformed into any desired voltage by either stepping it up or down to a desired voltage of the device being used. The inverter basically uses some transistors to convert the power from DC to AC. This process is not as complex as it looks. For the purpose of this article, I will give just a summary form of the same. Now a days, inverters are installed in many devices such that, they can be powered directly from Solar charged batteries e.g. street and traffic lights, street cameras, etcetera. Essentially, there are two forms of electrical power in the Universe: Direct Current (DC) and Alternating Current (AC). Direct current flows continuously from the positive electrical pole to the negative electrical pole. Alternating current flows back and forth between the two poles. DC current occurs in Nature and batteries, while AC current is man-made and supplies power through the public utility companies like ELECTROGAZ that supports human activities like industries and home use etc. Car batteries presented a problem in that, when one wanted to use them to run traditionally AC-powered devices in their cars, they could not do so because of incompatible current requirements. Manufacturers like Vector stepped up to solve this dilemma by working to design car power inverters that would safely and efficiently convert DC to AC. Their successful engineering has resulted in a wide range of compact, rectangular devices that connect to batteries and output the resulting alternating current safely through standard electrical sockets. Two factors determine how a power inverter works and these are; wave output and wattage output. Wave output describes the physical appearance of electrical signals as they move across an oscilloscope. Square waves appear exactly as their name specifies: like squares on a grid. Pure sine waves, also called true sine waves, appear as visible waves on the screen. Sine wave power inverters work better than square wave power inverters when uninterrupted power flow is a critical issue. In fact, true sine output is sometimes slightly superior to that of public utility power grids! Because of this, they are also the most expensive devices of their kind on the market. Recent advancement in technology has led to the entry of a hybrid design generally referred to as either a modified square or modified sine wave power inverter. The technical differences that determine how a true sine power inverter works and how a modified sine power inverter works are too minor to produce any noticeable effects with standard electronics. Only the most sensitive high-end equipment requires true sine output, and the cost of these devices may justify the additional investment in pure sine technology to deliver maximum quality and reliable performance. A DC power is connected to a transformer through the centre tap of the primary winding. A switch is rapidly switched back and forth to allow current to flow back to the DC source following two alternate paths through one end of the primary winding and then the other. The alternation of the direction of current in the primary winding of the transformer produces alternating current (AC) in the secondary circuit. In this arrangement, the electromechanical version of the switching device includes two stationary contacts and a spring supported moving contact. The spring holds the movable contact against one of the stationary contacts and an electromagnet pulls the movable contact to the opposite stationary contact. eddie@afrowebs.com