Power surge impact in appliances

Voltage Surge/Spike

If more voltage is introduced than an electrical appliance is designed to handle, this is called a power surge or transient voltage. Any such voltage increase that lasts at least three nanoseconds is considered a surge. If the increase is only present for one or two nanosecond, that's called a power spike. Just like if having much more water in a hose than it can handle, having too strong a power surge can damage your electric appliance. The greater voltage that runs along the electric wires causes great heat that can burn up the wire. Even if the wire doesn't get burned up in a single power surge, the surge can damage the wire. So repeated occurrences of power surges can accumulate enough damage to the wires that the appliance eventually burns out.Two types of appliances

Different type of appliances have different behavior on voltage fluctuations. And if you are planning to put a voltage stabiliser, you need to work accordingly.

There are two kinds of appliances: 1) Without Motor (resistive load) and 2) With Motor (inductive load).

Appliances without motor include:

• • Luminaire like Bulbs/Tube lights/CFLs.

  • Heaters like water heaters and room heaters.

  • Electronics like Televisions/Music Systems/DVD/Home Theatre/ Laptops/Phones.

Appliances with motor include:

• • Air Conditioners

  • Refrigerators

  • Ceiling Fans

  • Mixer Grinders

  • Pumps

  • Washing Machines

Appliances without motors (resistive load) and their behaviour on voltage fluctuations

Appliances like luminaire (bulbs, tube lights and CFLs) and heaters (like room heaters and water heaters) do not need voltage stabilisers. When the voltage is less, less current flows through them. When voltage is more, more current will flow through them. So when voltage is less, the output of these appliances will be less or the bulb will give less light, room heater will heat less, water heater will heat slowly. And as the bulb will give lesser light the power consumption of the bulb will be less. In fact many municipalities reduce the voltage of street lights at times when the light requirement is less to reduce the power consumption of the bulbs. However when the voltage is higher than normal, more current will flow through these appliances. And if the high voltage is consistent, and thus the high current is consistent, it may result in burning of the bulb or the appliance. If it does not burn, it will consume more electricity.

Most electronics like TVs, DVD players, etc do not work at 230 V. These appliances have an internal device called SMPS (Switch Mode Power Supply) which converts incoming 230 V to 12V or 24V (whichever is required by the appliance). Thus none of the electronic appliances need voltage stabilisers. I repeat, electronic appliances do not need voltage stabilisers. They are neither impacted by high voltage, nor by low voltage. So electronic devices do not need any protection. There are products available in market because people feel the need of protecting their appliances, but these devices do not need any protection. The power consumption of electronic products does not change with voltage fluctuations. Also, their output does not change.

Appliances with motors (inductive load) and their behavior on voltage fluctuations

All appliances with motors have an operating voltage range. Appliance like a ceiling fan have much larger operating voltage range and thus they are able to work even at lower voltages. But appliances like air conditioners have very small operating voltage range and thus they do not work at low voltages. If the voltage provided to them is lower than their operating voltage range, then either they will not start at all, and if they are already running, they will start producing a humming sound. This humming sound happens as these motors draw more current to run the system. This can lead to over heating and burning of the motor if persistent. Thus saving induction motors from voltage fluctuations is very important.

At high voltages these appliances draw more current only at the time of starting, but once they reach steady state the current is much less. But still the high starting current can damage the system and thus appliances with motors need to be protected both from high as well as low voltages. So you do need to put voltage stabiliser to protect these appliances. However before putting a voltage stabiliser, it is very important to find the operating voltage range of the appliance and the fluctuations that happen in your area. For e.g several refrigerator models available in market these days have large operating voltage range and thus these models do not need voltage stabilisers (unless your voltage goes below the operating range).

As far as power consumption of appliances with motors is concerned, it depends on the voltage as well as the load on the machine. Typically if the load is less than efficiency of the motor is less at standard voltage. For example, if your room need 0.5 tons cooling and you put 1.5 ton AC, efficiency will be lower but you get the advantage of quick cooling. If your washing machine can handle 7 kg load and you have put just 2 kg, then its efficiency will be low. This is because you are using more energy to do small work. However at lower load if the voltage is less, the efficiency improves. So if you know that your AC is oversized and input voltage in your house is 200 V or 210V then energy consumption will be lower.

Solution

Standby UPS

The standby UPS is the most common type used for desktop computers. In the above block diagram, the transfer switch is set to choose the filtered AC input as

the primary power source (solid line path), and switches to the battery/inverter as the backup source should the primary source fail. When that happens, the transfer switch must

operate to switch the load over to the battery/inverter backup power source (dashed path). The inverter only starts when the power fails, hence the name "standby." High efficiency,

small size, and low cost are the main benefits of this design. With proper filter and surge circuitry, these systems can also provide adequate noise filtration and surge suppression.

References

https://www.bijlibachao.com/appliances/voltage-stabilizer-for-television-refrigerator-air-conditioner.html

http://science.howstuffworks.com/voltage-surges-spikes-different.htm

http://www.apcmedia.com/salestools/SADE-5TNM3Y/SADE-5TNM3Y_R7_EN.pdf?sdirect=true