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Information About Brownouts in Electricity and its Safety Measures

Information About Brownouts in Electricity
Brownouts not only result in the malfunctioning of electric appliances, but can also cause serious damage to some of them. In this HomeQuicks post, we tell you what causes brownouts in your home, and how you can keep your valuable appliances safe from the damage caused by it.
Satyajeet Vispute
Last Updated: Feb 26, 2018
Brown or Black?
Often, people confuse a brownout with a blackout. Even in some media reports previously, the term brownout has wrongfully been used to describe an intentional or unintentional complete power outage, otherwise also known as a blackout.
The term brownout originates from the dimming effect of light when the voltage applied to it sags. It is defined as a drop in voltage below the rated value in an electric power supply system. Brownouts are exactly opposite to power surges, wherein the voltage and proportional current tends to steeply rise for a short duration.
Brownouts are intentionally caused by electric power supply companies to reduce load during a state of emergency. This reduction may last from a few minutes to up to several hours. Such intentional brownouts are induced as a preventive measure against a complete power outage situation, known as a blackout.
Brownouts can also take place unintentionally due to disruptions in the normal electrical power supply-to-demand ratio. For example, if there is a malfunction at the supplying end, leading to lower power generation, it can lead to a brownout. Also, if a device connected to the grid suddenly demands a lot of power, again, a brownout may be the result.

In the following sections, we will look at how brownouts affect various electric appliances that we use, and what can be done about it.
Brownout and Appliances
Brownouts, whether intentional or unintentional, always have undesirable effects on various electric appliances that are connected to the supply grid. These effects also vary from one device to another. Some devices are severely affected, while others may remain immune to the problem. The following list describes the effects of brownouts on some commonly used electric devices.
► The heat generated by a resistance device, such as a clothing iron or an electric heater, is equal to the true power which is dependent on the applied voltage. Mathematically speaking, if the resistance is kept constant, the power consumed will be directly proportional to the square of the voltage. Hence, even if there is small drop in the input voltage, such as during a brownout, there will be a significant reduction in the heat output.
Clothing iron
► In another resistance device―the incandescent light bulb―the dip in voltage will cause lower heat production in the filament, which will in turn decrease the amount of illumination that it produces.
Incandescent light bulb
► Electric motors such as induction motors, commutated motors, or universal motors, will typically run at lower speeds under no-load condition in the event of a brownout. However, under load, these motors will draw more current in order to compensate for the dip in voltage, in order to fulfill the power requirements. This rise in the current drawn can cause the motor to overheat and get damaged.
Induction motor
► In an unregulated direct current power supply, such as the ones seen in older generation electronic devices, like CRT TVs, the output ripple voltage will decrease in proportion to the decrease in the input voltage during a brownout. This will typically cause the on-screen picture to shrink in size, and become dim and fuzzy.
► Regulated DC power supplies found in the more modern electronic appliances will regulate the voltage in case of a drop, keeping it constant, in most cases. However, if the brownout is severe, then it may happen that the input voltage drops below the rated drop-out voltage of the regulator. In this case, the voltage output of the regulator will drop, and high levels of ripples originating from the filter capacitors will appear at the output.
DC power supply
► In case of a switched mode power supply (SMPS), if the input voltage dips, the current drawn will increase proportionally to maintain the original output voltage and current, until it finally malfunctions.
► In digital circuits of modern times, a brownout can lead to the generation of errors in the control system. The digital logic is dependent on two distinct voltage levels which are used to represent the bits 1 and 0. Decreased input voltage can cause these voltages to decrease as well, and as a result, the digital controller is unable to distinguish between them, and thus malfunctions. This can prove to be disastrous in critical electronic equipment, such as those used in a medical facility.
What to Do During a Brownout
Lights, being simple resistance-based appliances, are immune from damage due to brownouts. Luckily, they are also the most sensitive to drops in voltage. So, if you notice that the lights in your house are flickering, or have dimmed, you should take it is an early sign of a brownout.
The first thing to do then would be to switch off and unplug all the major appliances at your home, including computers, TVs, printers, cell phones, routers, etc., to protect them from damage.

Secondly, you should try to reduce the overall power consumption in your house. For that, you should switch off the heavy electricity consuming devices, such as heaters, washing machines, air conditioners, dishwashers, etc.

The time duration for which these devices should not be used will depend on how long the brownout lasts. Most commonly, this duration will range from only a couple of seconds to a few minutes, but in rare cases, may even last for a few hours.
Turn off tv
How to Protect Against Brownouts
Using an uninterrupted power supply (UPS) is perhaps the best solution for protection against brownouts. These devices store electric power in the batteries that are connected to them. They also include a circuitry that is able to sense when the input voltage dips, and in response, compensate for the power loss via the power stored in the batteries.
It must be noted, however, that a UPS is not really cheap, and therefore only worth investing in if they are to be used for protecting costly or critical appliances and devices. Also, the UPS needs to be maintained properly at all times.
Brownouts are instances wherein the voltage supply to our homes takes a temporary dip. Whether intentional or unintentional, it always brings with it certain undesirable and even harmful effects. However, now that you know what it is and what are its signs, you are in a much better position to handle a brownout situation, and protect your valuable electric and electronic devices against it.