Everything You Need To Know About Neutral Grounding Resistor

Everything You Need To Know About Neutral Grounding Resistor

A neutral grounding resistor (NGR) is an essential part of electrical systems, designed to reduce fault currents and shield equipment from harm. Its three main purposes are to prevent electrical overloads, preserve system stability, and guarantee asset and personnel safety. The types, designs, principles of operation, benefits, uses, upkeep procedures, and potential future trends of neutral grounding resistors will all be covered in this article. You will have a firm grasp on NGRs and their essential function in electrical engineering by the time you finish reading this extensive article.

What is a Neutral Grounding Resistor?

The primary function of a Neutral Grounding Resistor (NGR) in electrical systems is to facilitate the flow of fault currents to the ground. Its primary purpose is restricting the amount of fault currents arising from electrical malfunctions such as insulation failures or short circuits. The NGR efficiently lowers the fault current to a safe level by adding resistance to the neutral grounding line, eliminating excessive current flow that can harm equipment or provide a safety risk.

In addition, the NGR is essential to the system’s equipment protection. By managing fault currents, it assists in preventing overheating and damage to transformers, generators, and other delicate electrical components. This protection covers the whole electrical network, guaranteeing the equipment’s lifetime and dependability.
Regarding safety, the NGR greatly lowers the possibility of electrical shocks and fires caused by uncontrolled fault currents. It contributes to the upkeep of a steady and balanced electrical system, reducing interruptions and guaranteeing a secure work environment for employees.

These features emphasize how crucial neutral grounding resistors are to electrical systems. They regulate fault currents, safeguard hardware, and maintain general safety.

Types of Neutral Grounding Resistors

Types of Neutral Grounding Resistors

There are various varieties of Neutral Grounding Resistors (NGRs), each with unique advantages and applications in mind. These include:

High-Resistance NGRs

These NGRs have a relatively high resistance value, usually ranging from several hundred ohms to several kiloohms. They are frequently utilized in low-voltage systems to gradually restrict fault currents and lessen the strain on equipment during faults. Their advantages include lessened mechanical and heat strains and better equipment protection.

Low Resistance NGRs

Low-resistance NGRs, as opposed to High-Resistance NGRs, typically have lower resistance values, ranging from a few to tens of ohms. When quick fault clearance is crucial, they are used in medium-to-high-voltage systems. Low-resistance NGRs provide faster fault current limitation and reduce equipment damage and system downtime.

Arc-Suppression Resistors

These customized NGRs incorporate arc-suppression technology to extinguish arcing faults rapidly. They are essential in high-voltage systems where arc flash risks are a concern. Arc-suppression resistors increase safety by lowering the possibility of arc flash accidents and safeguarding people and property.

Every kind of NGR has different uses and advantages, meeting the demands of various electrical systems while guaranteeing maximum efficiency and security.

Arc-Suppression Resistors

Design and Construction

Neutral Grounding Resistors (NGRs) are meticulously engineered and built to guarantee dependable operation and longevity in electrical systems. The design generally calls for premium materials and specific building methods appropriate for different situations.

Materials Used

Nickel-chromium (NiCr) alloys and stainless steel, two high-resistance alloy materials, are frequently used to build NGRs. These materials’ outstanding electrical characteristics, corrosion resistance, and thermal stability are crucial for withstanding electrical strains and climatic conditions.

Construction Techniques

Usually, NGRs are built as resistor elements enclosed in sturdy enclosures for protection and insulation. Because the resistor elements are made to withstand the rated fault current without overheating, they guarantee dependable performance even in the event of a problem. Electrical integrity and resistance are maintained to a minimum by carefully designing connections.

Considerations for Various Environments

Depending on the application and environment, NGRs may include extra safety features such as weatherproof enclosures, thermal insulation, and corrosion-resistant coatings. Specialized designs may also include simple installation, maintenance, and monitoring features to improve total system reliability.

Because of these design and construction concerns, neutral grounding resistors are more effective and durable, making them essential parts of electrical systems in various sectors.

Working Principle

The function of Neutral Grounding Resistors (NGRs) is to provide controlled resistance into the neutral grounding route of electrical systems. When a system failure, such as a short circuit, happens, the NGR restricts the fault current by obstructing its passage through the neutral conductor. This regulated resistance successfully lowers the fault current’s amplitude, averting an excessive current flow that can harm machinery or endanger public safety.

NGRs are vital to the system’s stability because they restrict fault currents. They aid in preventing voltage fluctuations that may arise under fault circumstances, such as dips or swells in voltage. NGRs also help balance phase voltages and currents to maintain a balanced and stable electrical system.

Generally speaking, NGRs function by controlling fault currents, safeguarding machinery, and enhancing the stability and dependability of electrical systems.

Advantages of Neutral Grounding Resistors

Neutral Grounding Resistors (NGRs) provide several significant benefits in electrical systems.

  • Fault Current Limitation:By limiting fault currents, NGRs lessen downtime and equipment damage during electrical outages.
  • System Stability:NGRs minimize voltage disturbances and ensure smooth operation by balancing phase voltages and currents, contributing to system stability.
  • Equipment Protection:NGRs prolong the life of equipment by shielding delicate components from heat and mechanical strains brought on by high fault currents.
  • Safety:In the electrical environment, NGRs improve overall safety for people and assets by lowering the danger of electrical shocks, fires, and arc flash accidents.

Advantages of Neutral Grounding Resistors


Neutral Grounding Resistors (NGRs) are widely used in a variety of contexts and sectors, such as:

  • Power Generation:NGRs play a critical role in power plants by controlling fault currents and safeguarding distribution systems, transformers, and generators.
  • Industrial FacilitiesNGRs are used by the manufacturing, mining, and petrochemical industries to protect equipment and guarantee continuous functioning during an electrical outage.
  • Commercial Buildings:NGRs are placed in commercial buildings to preserve electrical system stability, guard against equipment damage, and improve occupant safety.
  • Renewable Energy:In renewable energy systems, like wind and solar farms, NGRs control fault currents and enhance system efficiency.

Maintenance and Testing

Neutral grounding resistors (NGRs) must undergo routine testing and maintenance to function as reliably and optimally as possible in electrical systems. Common maintenance procedures include visual examinations for corrosion or damage, tightening up connections, and confirming the integrity of resistor elements.

Testing procedures include measuring resistance values, conducting insulation resistance tests, and running fault current simulations to verify NGR functionality under fault situations. Regular testing and maintenance assist in detecting possible problems early, stopping equipment malfunctions, guaranteeing adherence to safety regulations, prolonging the life of NGRs, and improving system reliability.


In conclusion, the importance of Neutral Grounding Resistors (NGRs) in electrical systems cannot be overstated. They are crucial for maintaining system stability, protecting equipment, and reducing fault currents. Regular testing and maintenance are essential to ensure the effectiveness and reliability of NGRs.

NGRs significantly minimise costly damages, enhance security, and optimise network efficiency. It is vital to encourage further research and education in this field as it benefits electrical professionals and industries. By staying informed and adhering to best practices, we can enhance overall system resilience and leverage the benefits of neutral grounding resistors.

With over 20 years of experience in the electronic components market, RANTLE understands the evolving nature of the global electronics industry supply chain. As challenges and opportunities coexist, we serve as an independent electronic components distributor, assisting you in finding the right electronic components based on your needs. For reliable electronic components and expert guidance, partner with RANTLE to navigate the dynamic landscape of electrical systems effectively.

Last Updated on April 23, 2024 by Kevin Chen

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