NGR Neutral Grounding Resistors

In medium-voltage electrical systems, neutral point protection is critical to ensure service continuity and protect equipment. Neutral Grounding Resistors (NGRs, also known as NERs), also called neutral-to-ground resistors, are the most efficient solution to limit phase-to-ground fault current, minimize damage, and drastically reduce downtime.

Resistencia NER KLK para puesta a tierra de neutro en media tensión
Electrical Distribution Line | KLK NGR Neutral Grounding Resistors

What is a Neutral Grounding Resistor (NER) and What is it Used For?

A Neutral Grounding Resistor (NER) is a component that connects the neutral point of a transformer or generator to ground through a defined ohmic value. Its primary function is to limit the current flowing in the event of a phase-to-ground fault, thus preventing severe equipment damage and improving system safety.

KLK’s Neutral Grounding Resistors combine custom engineering, international certifications, and advanced monitoring technology to ensure reliability in critical medium-voltage networks.

The operating principle is based on inserting a controlled resistance between the neutral and ground, which reduces fault current magnitude and facilitates fault detection and location.

  • Protects transformers and generators from destructive overcurrents.
  • Minimizes the risk of electrical fires.
  • Enables fault detection through protective relays.
  • Maintains system stability during incidents.

Advantages of NERs Over Other Grounding Methods

  • Precise fault current limitation: prevents major damage and reduces repair costs.
  • Easier fault detection: controlling fault current magnitude allows protection systems to operate more accurately.
  • Prevention of transient overvoltages: protects sensitive equipment and extends service life.
  • Design flexibility: adaptable to different voltage levels, power ratings, and environmental conditions.
  • Reduced operational risk: greater control in critical systems such as mining plants or renewable substations.

Custom Manufacturing and Modular KLK Design

At KLK Electro Materiales, we understand that every electrical installation has unique requirements. That’s why our NERs are manufactured through a fully customized process:

  1. Definition of electrical parameters: nominal voltage, fault current, and maximum event duration.
  2. Energy calculation: determining the energy (E) in Joules the resistor can absorb without exceeding its maximum temperature.
  3. Modular design: adapts to available space and simplifies installation and maintenance.
  4. Material selection: stainless steel, special coatings, and high thermal conductivity active elements.
  5. Integration of Power Monitor: remote control of temperature, current, and operating status.

Thanks to this methodology, our resistors can be installed in extreme climates, from high-temperature deserts to marine environments with high salinity.

KLK NER Neutral Grounding Resistor under manufacturing

KLK Technicians Adjusting a NER | KLK Power Resistors

Certifications and International Standards

Our NERs comply with:

  • REPRO Achilles: accreditation for power networks in Europe and Latin America.
  • IEC and IEEE standards, plus country-specific requirements.
  • Tested in international laboratories to guarantee performance and safety.
  • Approved by major utilities such as ENDESA, ENEL, and power companies in Asia and the Middle East.
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Sectors and Applications

Mining

In open-pit and underground mines, NERs protect substations from extreme load and weather conditions. Their rugged design ensures continuous operation even with vibration, dust, and moisture.

Renewable Energy

In solar and wind farms, NERs prevent transformer damage and improve network availability—critical for meeting supply contracts.

Medium-Voltage Power Networks

In industrial and urban distribution, they reduce outages and improve supply quality during single-phase faults.

Real-Time Monitoring with Power Monitor

Continuous monitoring is key to extending the service life of an NER. Our Power Monitor system allows you to:

  • Measure temperature and current in real time.
  • Detect overloads or anomalies before they become critical failures.
  • Schedule predictive maintenance.
  • Send automatic alerts to control centers.

Modular neutral grounding resistor with Power Monitor system

Power Monitor Unit | KLK Power Resistors

Conclusion and Technical Contact

KLK’s Neutral Grounding Resistors (NERs) combine custom engineering, international certifications, and advanced monitoring technology to ensure reliability in critical medium-voltage networks.

Get in touch with our technical team and find out how a KLK NER can improve the reliability of your installation.

Frequently Asked Questions About Neutral Grounding Resistors (NGRs)

It is calculated based on the voltage, fault current, and the maximum event duration, taking into account the amount of energy it can dissipate without exceeding its thermal limit.

Yes. Using corrosion‑resistant materials and application‑specific finishes—such as protective coatings and specialized paint systems—they can withstand harsh environments, including desert and tropical conditions.

With integrated monitoring (optional), maintenance is limited to periodic inspections and preventive cleaning.

Yes, we develop custom solutions for both medium- and high-voltage levels, as well as adapting to the project’s physical dimensions.\*

(*)Each KLK power resistor requires a preliminary study to assess its feasibility.

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