What is a Surge?

Surges are sudden and unwanted increases in voltage that can damage, degrade, or destroy electronic equipment within any office, hospital, commercial building, or retail store, or other facility.

Every piece of electrical equipment is designed to operate at a specified nominal voltage such as 120v ac, 240v ac, 480v ac, and so on. Most equipment is designed to handle minor variations in their standard nominal operating voltage; however, surges can be very damaging to nearly all equipment.  

What causes surges?

A common source for surges generated inside a building is devices that switch power on and off. This can be a simple thermostat switch operating a heating element to a switch-mode power supply found on many devices. 

Transients can originate from inside or outside a residence:

Inside: 

• Large, motor-driven appliances such as washers, dryers, refrigerators, thermostats, and heating and cooling equipment

Outside:

• Nearby lightning strikes

• Bird or squirrels making contact with power line equipment

• Accidents involving utility poles

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Are All Power Quality Problems Surges?

No, surges, or transients, do not explain all of the voltage-related power quality issues in the world today. 

• Drops in voltage that last a fraction of a second to as much as a few seconds are known as voltage sags.

• Voltage drops that last several seconds or even minutes are known as brown outs. Both sags and brownouts are more damaging to motor loads than they are to microprocessor based equipment. 

• Sustained over-voltages are known as voltage swells and can last from a few seconds to several minutes. Sustained over-voltage conditions can be very damaging to many types of equipment, but are not nearly as frequent as transients or surges.

Power outages are another type of power quality issue that can last from several seconds to hours or even days. 

Surge protective devices (SPDs), also known as transient voltage surge suppressors (TVSS), do nothing to prevent the harm that can be caused by power outages. 

Equipment can be protected from the damaging effects of power outages by utilizing either uninterruptible power supplies (UPS systems) or standby power generating equipment. 

Many other power quality issues exist that all users must be aware of. A partial list of these problems includes:

• Harmonics

• Circulating ground currents

• Noise

• EMI/RFI interference

No power quality product is a cure all to all of these issues. Proper diagnosis is the key to good power quality and the minimization of lost productivity.

Since it is impossible to prevent voltage surges from either entering a building or from occurring inside a building, surge protection was invented. The function of the surge protector is to stop (or at least limit) the effects of less-than-perfect power quality on solid state electronic devices.

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