Protecting electrical appliances
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A good voltage stabilizer has a part to play in your home.
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Offering protection: Voltage stabilizers can help protect expensive equipment.
Almost all electrical and electronic home appliances work on electricity input from the AC mains. A steady power supply at the rated frequency and voltage is important for the smooth functioning of these devices. However, the AC mains supply will be often affected by problems, which, in turn, will affect the quality of the power delivered. A quality single-phase power supply will have a steady rated voltage of 230 plus or minus 10 volts, at a constant supply frequency of 5
0 Hz. But improper maintenance of distribution lines, loose connections, overloading and so on can cause problems such as low or high voltage or intermittent power, which may cause malfunctioning of appliances. As many electrical and electronic devices cannot withstand such severe fluctuations, they may not run or get damaged.
Is it possible to get an appliance with wide voltage ratings to withstand such problems? Yes, there are equipment available in the market with wide input voltage ratings. Many low power devices such as compact fluorescent lamps and radio receivers use power electronics to enable the device to be connected to varying supply from 100 volts to 280 volts. However, if this technology is to be adopted for high-power devices such as refrigerators, air conditioners, washing machines, mixer-grinder and so on, the cost can get high.
Some refrigerator manufacturers do claim that their products can work on varying supply voltages.
They have achieved this by designing the compressor motor in such a way that it can withstand the excess heat generated when working under low voltage or by ensuring that the compressor is switched off when the motor gets overheated.
This type of appliance will work fine if the duration of the high or low voltage condition are only for a short duration, say for one or two hours. Otherwise, it is better to go for a good electronic voltage stabilizer. Voltage stabilizers are designed to fight against voltage fluctuations and irregular power supply and protect electrical appliances from getting damaged from these problems. They are connected between the AC power and the electrical appliance so that the power flows into the stabilizer first.
An ideal voltage stabilizer corrects the voltage fluctuation by either boosting (enhancing) the supply voltage to the required level when supply voltage is low or by bucking (reducing) the voltage if the supply voltage is in excess. The stabilizer will protect the appliance by cutting off the power to the appliance if the supply voltage is dangerously high, low or unstable. A good voltage stabilizer also provides a start-up delay function which restarts the connected equipment once the voltage is at a safe level. This function is essential for appliances such as air conditioners and refrigerators that use compressors.
Some tips
•Power rating: Power-handling capacity of the stabilizer is important for the safe and economical use of appliances. It is always better to select a stabilizer with capacity slightly higher than the power rating of the appliance for which it is used. Another important parameter is the current rating of the stabilizer. As most of the electrical appliances tend to draw more current when they start, the stabilizer must be powerful enough to supply the required starting current to the appliance during start-up. You can ask your electrician or appliance dealer to help you buy the right stabilizer.
•Input voltage range: A voltage stabilizer will work only within a specified voltage range.
But they come in different input voltage ranges such as 150 V to 275 V and 130 V to 300 V. A wide-range stabilizer will be ideal if you are not sure about the supply voltage. And it is always wise to select a stabilizer suitable for the voltage variations expected. If your house is located close to a distribution transformer, it is likely that you may experience more of high than low voltage. To combat high voltage, you will need a stabilizer with less boost and wide buck. On the other hand, if you are located far away from the distribution transformer, you are likely to experience low than high voltage. In that case, you will need to select a stabilizer that can work in low voltage conditions.
•Low and high voltage cut-off: If the supply voltage goes to an extremely high or dangerously low level, the stabilizer will no longer be able to provide the required output. Under this condition, a stabilizer with high/low voltage cut-off will disconnect the appliance from the AC mains, thus protecting the device.
•Intelligent time-delay system: Refrigerators and air conditioners come under this type of electrical appliances. Such devices can be safely switched on only if the time gap from the previous switch off is greater than a specified value of 3 minutes.
•After-sales service: A good and easily available after-sales service will be of help.
T.K. MANI
Principal, College of Engineering, Cherthala.
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