With the expansion of electric power in today’s world, the electrical power systems are exposed to many critical conditions like overvoltages and voltage surges due to lightning strikes or abrupt switching conditions. The main concern is the overvoltage condition which may cause serious damage to the system’s equipment. Therefore, it is necessary to install a device that guarantees protection from the condition where over or under-voltage occurs.

A surge protector is a device that is connected to protect a system against overvoltage. These devices can be used for multiple applications but they are generally used against voltage transients.

We just launched our Power Systems Engineering Vlog series and in this series, we are going to talk about all sorts of various power system engineering studies and commentary. We will overview the different blogs written by AllumiaX. It’s fun, it’s lively, it’s a video blog essentially and we hope you’ll join us and benefit from it.


Surge Protective Devices are the devices that are used to protect the system from voltage spikes. SPDs are normally designed to perform a set of function-specific tasks.

The term surge protection device (SPD) is used to describe electrical devices typically installed in power distribution panels, process control systems, communications systems, and other heavy-duty industrial systems, for protection against electrical surges and spikes, including those caused by lightning.

​The surge protective devices are categorized as:

  • Surge Arresters
  • Surge Protectors

Surge Arresters VS Surge Protectors:

​Surge protectors and surge arresters are used for the same work, i.e., protecting equipment from electrical surges. However, many people are confused about their applications. This problem occurs in a number of important areas within an industry.

Surge Arresters: Surge arresters are usually installed in the substations to protect the equipment by eliminating the effects of lightning and switching over-voltages.

Surge Protectors: The main job of a surge protector system is to protect electronic devices from “surges”. A surge protector attempts to limit the voltage supplied to an electric device by either blocking or shorting current to reduce the voltage to a safe threshold.

How does a Surge Protector work?

A surge protector allows the electrical current to flow from the outlet to a number of electrical and electronic devices plugged into the power strip. Here is what happens when the voltage from the outlet surges or spikes rise above the accepted levels.

Types of Surge Protection Device:

According to the standards, surge protective devices are classified into three different types:

  • High voltage SPD
  • Medium voltage SPD
  • Low voltage SPD

Low voltage SPDs do not limit the voltage like high voltage and medium voltage SPDs. Low voltage surge protectors are further divided into three classes:

Type 1: This type of SPD is used in industrial buildings to protect insulation levels against external surges caused by lightning. Their installation can be done on a variety of Electrical Systems. It protects the system from direct lightning strokes.

Type 2: The type two of low voltage SPDs differs from type 1 based upon their installation. These types of SPDs prevent the spreading of overvoltage to the installations.

Type 3: These types of SPDs are usually installed after the main breaker and are used as a complement for type 2.

Electrical Surges: how do they occur?

The most reoccurring cause of surge is lightning. During a lightning storm, it may strike somewhere near a power source and affect the voltage running through it. The results are oddly different when a lightning surge hits an electrical system.

Surge arresters guarantee the protection of Electrical systems through a very simple process.

How does Surge Arresters Work?

A surge arrester is connected in parallel with the equipment that needs to be protected. These surge arresters limit the over-voltages occurring in the equipment.

The highly non-linear characteristic of an arrester provides it with various multi-tasking abilities. A surge arrester usually contains a ground terminal as well as a high-voltage terminal.

To eliminate insulation failure, the arrester should be applied properly so that the equipment insulation isn’t exposed to over-voltages. It is important to select the arrester parameters correctly in order to avoid problems in the system.

Importance of Surge Arresters:

A surge arrester protects the equipment from surges or transient voltages in electrical power systems, occurring from lightning or a switching surge. Not only does it operate the extra voltage into the earth wire but it also allows the normal voltage to continue its path.

Furthermore, in order to eliminate unwanted voltage spikes and transients at a commercial scale, it is pretty much imperative to conduct an efficient Load Flow and Short Circuit Analysis. Such can be positively done by hiring a professional Power Systems Engineer. Doing so would result in a stable Electricity supply maintained constantly throughout your daily industrial operations and would also ultimately result in an overall lower Power Consumption rate saving the company from unwanted penalties.

Let us know if you have any queries regarding this topic and do provide us with your feedback in the comments.

Hiring a professional electrical engineer to conduct an Arc Flash Analysis and Short Circuit Study is a great way to ensure the safety of your facility and workers against unwanted incidents.

AllumiaX, LLC is one of the leading providers of Power System Studies in the northwest. Our matchless services and expertise focus on providing adequate analysis on Arc Flash, Transient Stability, Load Flow, Snubber Circuit, Short Circuit, Coordination, Ground Grid, and Power Quality.

To learn more about AllumiaX in detail, follow us on Facebook, LinkedIn, and Twitter and stay updated with all the latest news regarding electrical engineering.
Call Us: (206) 552–8235

About The Author

Abdur Rehman is a professional electrical engineer with more than eight years of experience working with equipment from 208V to 115kV in both the Utility and Industrial & Commercial space. He has a particular focus on Power Systems Protection & Engineering Studies.

Abdur Rehman is the CEO and co-founder of allumiax.com and creator of GeneralPAC by AllumiaX. He has been actively involved in various roles in the IEEE Seattle Section, IEEE PES Seattle, IEEE Region 6, and IEEE MGA.

Leaders in Industrial & Commercial Power Systems Engineering