How Does a Surge Protector Work

With technology making tremendous strides over the last few decades, homes, apartment buildings, office complexes, hospitals, factories, warehouses and other environments have seen a proliferation of important and expensive electrical devices and electronic products. End-users in residential homes and apartment buildings rely on an array of devices, from micro-waves and clothes dryers to computers and home entertainment systems, designed to enhance their lifestyles. Businesses and other organizations depend on equipment and devices that use electricity, including phones, computers, scanners, copiers, point-of-sale systems and countless machines tools and equipment to run their day-to-day operations.Today, whether used for personal consumption or commercial endeavors, many of these products and devices have powerful but fragile microchips and other sensitive components. This increased reliance on electronic equipment and appliances has led to more susceptibility to power surges. In just nanoseconds, the same energy that powers this technology can stop it from working. Just a slight electrical disruption can have devastating consequences, varying from disruption to repair to complete ruin.

Business owners and C-Suite executives understand the importance of protecting mission-critical systems, equipment and devices from interruption. The consequences include increased downtime, budget surprises, greater capital outlays, lost revenues and angry customers. In some cases, the disturbance can mean the difference between life and death. However, end-users can take simple, proactive steps to ensure that all of their important communication, medical or production equipment has power surge protection.

In the United States, the standard voltage is 120 volts. A voltage level in excess of 120 volts points to a problem. Electrical power disturbances refer to abnormalities and deviations from the normal performance. Three things can affect the quality of electrical power: degradation, disruption and destruction. These forms of disturbances may last for a short period, be continuous, or last for a long period. Power disturbances have a variety names, including surge, sag, swell, transient, fluctuation, interruption and electrical line noise. A surge refers to an increase in power that lasts for three nanoseconds or more. An increase of one or two nanoseconds results in a condition called a “spike.” A surge or spike with a high enough level can do some serious damage on electronics and machinery.

Approximately 70 percent of electrical disturbances involve transient and electrical line noise, which includes electrostatic discharge, dips interruptions and surges. Outages, lightning, over-and under-voltages and swells/sags contribute to the remaining 30 percent of the disturbance issues.

Look at some of the most common forms of disturbances that exceed the threshold:

  • Lightning A typical lightning flash contains about 300 million volts of electricity, according to the National Weather Service. The volts and amperes in a direct hit may cause the most damage of the high-voltage transient. Even if your building or facility does not receive a direct hit, through the process of mutual induction, a conductive circuit located within just a few miles of a lighting strike can cause a several thousand volt transient that will leave electrical service panels vulnerable to power surges.
  • Utility switchingThis type of power disturbance can cause a compromise of the power quality. This occurs when the path of electrical power from a utility generated to a commercial building is not a dedicated line. It actually consists of a network of generators and substations that interconnect many facilities, sometimes over hundreds or thousands of miles. Ongoing changes in electrical demand or other service requirements typically result in the switching of network grid tie points. The process of switching a substation in and out of the network causes transients in voltage. This excess voltage can reach hundreds or thousands of volts depending on the current impedance and the facility’s distance from the switching points.
  • Capacitor switchingMany utilities and large commercial power companies compensate for excessive inductive loads such as motors, and increase power at the distribution extremities by adding power factor correction capacitors to the network. Typically, operators switch on the banks of capacitors at the same time every morning and switch them off at the same time each night. During the switching process, transients can reach hundreds or thousands of volts contingent on the impedance or distance of the affected equipment from the capacitor banks.
  • FaultsUtility distribution systems can have faults that generate surges. Noise from elevators, air-handling equipment or arc welders working on construction projects in nearby buildings can introduce damaging voltage spikes and electrical line noise. Sensitive microelectronics in products can suffer damage via the mere operation of PCs, telephones, air conditioning or other electronic devices and equipment. Even daily fluctuations from internal office equipment such as a copier—which is switched on and off frequently and is operated in cycles– can result in cumulative damage. Facilities that rely on a large amount of electrical equipment accumulate more transient voltage, which can create potential power disturbances and damage.

As you can see, electrical systems are vulnerable to multiple sources of power disturbances. Besides ensuring adherence to wiring, grounding and bonding standards, surge protection devices and other protectors can help prevent damage from surges and electrical line noise.

How Does a Surge Protector Work?

So how do surge protectors work? Most surge protectors have a component called a metal oxide resistor (MOV). The MOV, which forms a connection between the hot power line and the grounding line, has three parts: a piece of metal oxide material in the middle, connected the power and grounding line by two semiconductors. The two conductors have a variable resistance, which is dependent on the voltage. When the voltage is correct, the MOV remain the same and does absolutely nothing. If the voltage falls below a certain level, the electrons in the semiconductors flow in a manner that creates high resistance. When the voltage exceeds the correct level, the MOV acts like a pressure valve and conducts the excess current, which eliminates the extra voltage.

Surge protections come in many forms and can vary depending on the application, such as commercial, industrial and residential. Anyone who has assembled a computer system or home entertainment system has probably used the standard power strip, which functions as an indispensable piece of equipment. Many power strips also function as the Point-Of-Use Surge Protection device. Plug this surge protection device into one power outlet and it passes the electrical current along to a number of electrical and electronic devices plugged into the power strip. A SPD provides the necessary protection from surges in power. If the voltage from the outlet spikes or the surge exceeds the accepted level, the surge protector diverts the overage into the outlet’s grounding wire. Some power strips (not all) include the surge protector feature.

End-users can also choose to have their electrician install special outlets that offer surge protection in certain locations. For major appliances, such as refrigerators, ovens, washing machines and dryers, preemptive action is a small price to pay for protection in the event of a surge.

The Service Entrance Surge Protection Device, commonly installed in residential settings for whole house surge protection as well as commercial and industrial environments, provides a more comprehensive approach to surge protection. This type of SPD mounts at the entrance to the building and/or at the main electrical panel. It ensures protection for the entire electrical system–lights, outlets, light switches, motors and other hardwired equipment that do not plug onto a point-of-use surge protection device. Even if you have a point-of-use SPD power strip, the service entrance SPD reduces the voltage before it reaches the point-of-use surge protection device.

Considerations for Integration of Surge Protector in Main/Distribution

Today, most manufacturers incorporate some form of surge protection within the power distribution or branch panels. Compared to external surge protection devices, this approach offers a few advantages, including ease of installation product performance and less space requirements. As the end-user, it’s important to understand the risks of the integration of SPDs into distribution equipment:

1. Failure of SPD
When the internal MOVs reach the end of its useful life, they create a significant amount of power, which it releases in the form of heat. The intensity level of the heat can cause collateral damage to the distribution equipment.

2. Repair Challenges
When it comes time to repair a failed SPD, the service technician can take two approaches: remove all the power from the panel or remove only the power energizing the SPD and leave the remainder of the panel energized. Shutting off all of the power may be the safest option, but it may be the last choice in situations where the load may be too critical to shut down. This means that the technician must take extreme measures to wear special gear and utilize tools designed to provide protection from shock, electrical faults and potential arc flash.

3. Compromised Performance
The Underwriters Laboratories (UL) determines the application of the SPD.. In some cases, mounting the SPD a long distance away from the connection point affects performance. For example, the neutral bus bar may be as much as four feet away from the installed SPD, which could cause performance to be worse than on an optimally placed, externally mounted SPD.

Some end-users choose a hybrid design, which combines at least two types of surge components — such as MOVs and SADs. The advantage of the hybrid approach is the design shares the surge and limits the amount of surge through the SAD module to an acceptable level. The system diverts the remaining current to the MOV module. The hybrid design requires a significant level of engineering to properly utilize the strengths of each component and avoid their weaknesses.

Standards for Surge Protectors

The Underwriters Laboratories (UL) and the National Fire Protection Association provide the standards for surge suppression equipment. The standards and codes have undergone many changes to improve the safety of these surge protective devices. The current version of UL 1449 has combined all classification into a formal classification and identified them as four different types:

1. Type 1 SPDs
This type of surge protector installs between the secondary side of the service transformer and the primary side of a service entrance disconnect. Type 1 SPDs must have overcurrent protection either installed internally on the SPD or included with the device. Generally, electricians install Type 1 SPDs before the main service disconnect. Type 1 also works for Type 2 and Type 4 locations, such as end-use equipment and distribution panels.

2. Type 2 SPDs
This type connects on the load side of the main service disconnect, including SPDs placed at the branch panel. Some Type 2
versions have internal overcurrent protective components, but Type 2 SPDs can depend on service entrance overcurrent disconnect for overcurrent protection.
Type 2 SPDs consist of permanently connected devices that are installed on service equipment, distribution panels and end-use equipment.

3. Type 3 SPDs
This is not a cord-connected device and is intended for use in end-equipment location. Excluding the length of the SPD conductors, this type must be connected a minimum of 33 feet from the service entrance to the point of use. This type can rely on external overcurrent protective equipment for over current protection. Type 3 SPDs must comply with current leakage requirements to prevent unwanted currents from injection on the ground conductor.

4. Type 4 SPDs
These SPDs consist of SPD assemblies that would be incomplete in any way. The Type 4 SPD is also a label for any SPD component that could prevent the assembly from receiving UL Listing classification. Some examples include MOVs and any SPDs without outside enclosure.

A power surge can have a number of effects on equipment — from no obvious impact to total destruction. These surges can also cause semiconductors and other electronic components to deteriorate over time. A qualified electrician with the appropriate electrical safety training can assist customers and help them determine which type of SPD or combination of SPDs will protect their equipment and operations.

Everyone Needs Surge Protection Devices and a Certified Electrician

A wide variety of industries and organizations place a heavy reliance on the use of technology, electrical devices and electronic products, including: industrial parks, manufacturing plants, schools, churches schools, banking centers, hospitals, military installations, emergency centers, 911 operation centers, sporting complexes, corporate centers, chemical plants, oil refineries and more. Regardless of the application, all benefit from surge protection systems.

Safeguarding the integrity of equipment and electronic devices in a residential industrial or commercial environment is critical in keeping things running smoothly and protecting capital investment.

Along with other equipment, such as line conditioners, harmonic filters and uninterrupted power supply, certified electricians can offer customers a range of innovative and reliable surge protection solutions designed to help protect sensitive electronic equipment against the damaging effects of transients.

Regardless of the type of electrical disturbance, such as lightning, utility switching and load switching, surge protection devices can protect your customer’s power supply, minimize their downtime and safeguard their investment.

Learn more about being becoming a certified electrician in your state and electrical safety training at StateCE.