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Thanks to the inefficiency of the power sector and the poor power supply in most towns and cities in the country, power back-ups like the ‘inverters’ have become a necessity.`A0But unfortunately, in the absence of mandatory quality certification for these products, a consumer has no way of knowing the quality of the inverter that he buys. And when I refer to quality, I refer not just to its trouble-free performance, but also to its safety. Some years ago, a resident of Dilshad Garden in Delhi had a terrifying experience with the power inverter that he had bought. Just seven months after its installation, a representative of the company came for its servicing. While pouring water into the battery compartment, the person asked one of the residents of the household — a senior citizen — to check whether the water level was up to the mark indicated on the battery. Even as he bent to check, there was an explosion, and the acid that splurged from the battery injured the man. It burnt his clothes, his face and, worse, his eyes. In another incident, an inverter suddenly started making a strange, loud noise and when the consumer went to inspect, she found smoke emanating from it. By the time she`A0managed to disconnect it and switch off the power supply, the fumes had filled the house. The consumer said: "I shudder to think of what could have happened if I had not been home at that time or if this kind of problem had happened in the night when we were sleeping. The inverter could well have started a fire." In the absence of mandatory quality certification from a standards-making body like the Bureau of Indian Standards, consumers have`A0to exercise utmost caution while purchasing inverters. Besides looking at its quality, reliability, performance, safety and price, it is also equally important to look at the after sales service provided by the manufacturer or the dealer. Are the service personnel adequately trained for the task that they are expected to perform?`A0One has to look at these aspects carefully. It is equally important to buy a quality battery and ensure its proper maintenance. An inverter basically ‘inverts’ direct current voltage of a lead-acid battery into alternate current voltage, similar in most respects to the one coming from the power supply distribution system. So what are the important criteria that one must look for while buying inverters? According to Delhi-based consumer group Voluntary Organisation in Interest of Consumer Education (VOICE), which some years ago tested 10 brands of inverters in the market, factors that make a difference to the quality are features like insulation resistance, safety provisions, output voltage, switch-over time, robustness, and eco-criteria. An inverter not only has to provide a 230-volt alternate current, but it should also be as close as possible to the domestic power supply — the wave form of the power supply`A0should be sinusoidal. Says VOICE: If the supply is not sinusoidal, it produces undesirable heating in domestic appliances like fans, motors of`A0room coolers, etc, which in turn reduces their working life. In fact if the wave form is very different from the sine-wave, a humming noise can be heard, specially when fans and tube lights are used. Another important feature is`A0the time taken by an inverter to switch over from stand-by mode to the active mode and supply power and again switch back to the stand-by mode. The ‘battery charging’ qualities of an inverter are equally important because if it is too slow, it may not fully charge the battery when the next demand comes. On the other hand, if the charging rate is too high, it may reduce the life of the battery. VOICE also points out that the`A0inverter should have an in-built protection to stop ‘deep discharge’ of the battery below 10 volts. It should also have a tripping mechanism if it is connected to a higher load than what it is rated for. Again, as and when a light or a fan is switched on or off, the AC output voltage from the inverter varies.`A0These variations however should be within limits and the quality of this regulation of output voltage against different loads is an important quality parameter. An inverter should also have suitable and adequate provisions for cooling of the inverter as undue heating can cause the inverter to stop working. You cannot obviously check these factors at the time of purchase, but you can at least ask questions about these and make sure that the product that you are buying is safe. Eventually, mandatory quality certification is the answer.
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