IntroductionWe all take for granted the electricity that powers our stereo and home theater systems, computers and other appliances. We simply plug them in and enjoy music, movies and the many benefits they provide. Yet the vast infrastructure known as the power grid that delivers power to our homes and offices is subject to disturbances, interruption and other anomalies that can cause serious damage to all electronic components. This article examines the potential problems with the electrical power grid and the best ways to protect your valuable electronic components. It was written with the help of information provided by Innovolt, Inc., a manufacturer of power protection devices.
Five Most Common Power Grid DisturbancesIn some parts of the country, frequent lightning strikes can instantly destroy expensive electronics without warning. In other cases, brown outs, over voltages and current spikes caused by excessive power demand can also damage electronics. In short, the electrical grid that delivers power is subject to disturbances and potential failure. Recall the massive Northeast US power blackout in August, 2003, which affected 45 million people in 8 states. The failure was caused by a series of cascading events that led to the shut down of the entire grid in that region of the country.
You can check out the real-time condition of the power grid in your area by visiting i-grid , a website developed by the founder of Innovolt (requires signup).
- Voltage Spike: An instantaneous increase in voltage from 300 to 6000 volts (normal is 120 Volts) caused by lightning or grid fault
- Over Voltage: a longer-term event caused by a large load instantaneously taken off the grid causing voltage to rise above 138 volts
- Under Voltage (Brownout): Too much load on the power grid resulting in voltage decreases from 120 volts to below 90 volts
- Power Outage: Zero voltage lasting for 2 seconds to several hours
- Voltage Sag: Caused by a large load placed on the grid resulting in delivery of less than 100 volts for up to 2 seconds
Most Damaging Power Grid DisturbancesAll grid disturbances can potentially damage sensitive electronic components. According to a long-term analysis of i-grid data, the most common grid disturbances are the Voltage Sag events. In some cases, Voltage Sag occurs 30 to 100 times per year. The Under Voltage event is similar to a Voltage Sag, but last longer – sometimes for hours. Voltage Spikes can also cause serious damage, including fire, but are less common and damage can usually be avoided with an off-the-shelf surge suppressor, also known as a Transient Voltage Surge Suppressor (TVSS). Over Voltages are caused by load variations and might only last a couple of seconds. However, Over Voltages caused by loss of a Neutral connection will cause 120V to become 240V until the power company fixes it.
Under Voltage and Voltage Sag events in the power grid cause the most serious damage because they chip away at the integrity of our equipment with each event. And, there are a lot of Under Voltage and Voltage Sag events. When electronics such as audio receivers, televisions and appliances are powered on, there is a rush of incoming electrical current, known as a current surge or current inrush. Because of current inrush, most electronics use a THERMISTOR. A thermistor is a type of resistor whose resistance to the flow of electricity varies with temperature, hence the word therm•istor. A cool thermistor has a high internal resistance. When a component is turned on, the thermistor’s high resistance suppresses the current inrush. When the rush of incoming current has passed, usually after a second or two, the heated thermistor’s resistance drops to close to zero and allows the full amount of current to pass.
When a Voltage Sag or Under Voltage event occurs, it is also followed by a current surge or current inrush when the proper voltage is restored. The current inrush is similar to when the component was turned on. When the current inrush occurs, the thermistor is no longer effective since the component has been operating and the thermistor has warmed up. The rush of incoming current due to the Voltage Sag event is not suppressed and can cause serious damage. This applies to audio-video components, refrigerators, washing machines, computers and almost anything that plugs into the wall, especially products with microprocessors (which is almost everything). Microprocessors are particularly sensitive to small changes in voltage and current. A Transient Voltage Surge Suppressor (TVSS) only prevents voltage surges and cannot protect electronic components from a current inrush event.
Innovolt Introduces CVSSCVSS is Current – Voltage – Surge – Suppression. CVSS protects electronic components from all five of the major power grid disturbances, including Under Voltage and Voltage Sag, which result in damaging current inrush. CVSS is a patented technology recently designed and introduced by Innovolt.
CVSS technology is found in all Innovolt power protection products and according to the company it is the only product that protects components from current inrushs due to Voltage Sags. Innovolt power protection products insert a 'cold' thermistor in the electrical path within 2 milliseconds after an Under Voltage or Voltage Sag event to limit current inrush and prevent possible damage. When an Over Voltage occurs, CVSS reacts in less than 4 milliseconds to remove connected electronics from the power grid and disconnects from the power grid within two seconds for Under Voltages below 90 volts.