A Neutral Grounding Resistor (NGR) is an effective means for limiting fault current in industrial power distribution systems. Neutral Grounding Resistors are installed in series with a power system’s neutral grounding connection. By providing impedance, these devices can limit the ground fault current and mitigate damage that might otherwise result from a phase-to-phase grounding fault. A standard Avtron package consists of a single-phase, dry-type, Epoxycast™ transformer plus a secondary power resistor, mounted in a common enclosure.

NGRs are used to:

• Limit ground fault currents to safe levels.
• Protect equipment and personnel from high fault currents.
• Minimize damage during faults and enhance system stability.

During a ground fault, the NGR restricts current by adding resistance to the neutral-to-ground connection. This reduces the fault current to a manageable level, protecting the electrical system.

NGRs are commonly used in:

• Power generation plants.
• Industrial facilities.
• Mining operations.
• Renewable energy systems (e.g., solar and wind farms).

Key considerations include:

• System voltage.
• Desired ground fault current level.
• Duration of fault resistance (time rating).
• Environmental conditions (e.g., indoor or outdoor installation).

Yes, NGRs can be tailored to meet specific voltage, current, and environmental requirements.

• Low-Resistance Grounding: Limits fault current to 10–1000 A, used in medium-voltage systems.
• High-Resistance Grounding: Limits fault current to 10 A or less, used in systems where continuity is critical.