NGR (NEUTRAL GROUNDING RESISTOR) PANELS

Neutral Grounding Resistor (NGR) Panels feature two main neutral grounding methods: Low Resistance Grounding (LRG) and High Resistance Grounding (HRG). NGR is connected between the transformer neutral and earth to limit earth fault current to a safe value during ground faults.

Features

Enables quick fault detection and isolation without damaging equipment.
Reduces equipment damage, arc blast risk, and transient over-voltages.
Improves system safety, reliability, and protection during earth faults.

Advantages

Prevents overheating and reduces mechanical stress on cables, transformers, switchgear, and motors.
Improves personnel safety by minimizing fault energy and arc flash risk.
Helps isolate faults quickly and prevents fault propagation.

Low Resistance Neutral Grounding (LRG)

In a Line-to-Ground (L-G) fault, the protection system trips the circuit to clear the fault.
Limits earth fault current to a safe range of 100 A to 1000 A.
Zero Sequence Current Transformers (ZSCT) and Ground Fault Relays operate at 5–20% of maximum fault current.
LRG resistors are designed for 10 seconds duty with a maximum temperature rise of about 760°C.
System Voltage: 2.4 kV / 4.16 kV / 6.9 kV / 34.5 kV.
NGR Current Rating: 100 A - 400 A.

High Resistance Neutral Grounding (HRG)

Provides an alarm during a Line-to-Ground fault without tripping, ensuring continuous power supply.
Recommended for critical industrial processes where power interruption is unacceptable.
Limits the earth fault current to a low range of 5–10 A.
HRG resistors are designed for continuous duty with a maximum temperature rise of about 375°C.
Fault current threshold is maintained higher than the system’s total charging current.

Key Point

Commonly used in medium voltage mine power systems.
Limits earth fault current to 25–50 A to keep touch voltage within 100 V or less.

General Specifications

System Voltage Rating: 415V, 3.3kV, 6.6kV, 11kV, 22kV, and 33kV.

Neutral Current (Fault Current): Custom-calibrated range from 10A to over 3000A.

Time Rating: 10 sec., 30 sec., 60 sec., or Continuous duty options.

Corrosion-Resistant Enclosure: CRCA Sheet fabrication with up to IP55 / IP65 weather protection.

Integrated Sensing: High-accuracy Neutral Current Transformers (NCT) for protection coordination.

Premium Material Element: Built using high-grade alloys including Stainless Steel (SS304/316/410).

Resistor Construction: Available in coil type, punch grid, or wound type designs.

Neutral Grounding Resistor Panel System Unit

Neutral Grounding Resistor Panel Unit Overview

Salient Features

CT/PT-based metering and protection arrangement.
SCADA & Automation Compatible for remote monitoring.
Intelligent Continuous Monitoring systems.
Advanced Climate Management – Thermostat-controlled anti-condensation space heaters protect internal components from moisture.
Real-Time Diagnostics – Door-mounted digital indicators provide on-site telemetry for leakage current and temperatures.
Transient & Surge Shielding – Integrated heavy-duty surge arresters isolate the resistor matrix from high-voltage surges.

Industrial Applications & Sectors Served

Thermal & Hydro Power Plants.
Solar & Wind Farms.
Steel & Metallurgical Plants.
Cement & Chemical Plants.
Seaports & Marine Terminals – Weather-proof protection for shore-to-ship power and crane grids.
Pulp & Paper Mills.
Hyperscale Data Centers.
Hospitals & Critical Healthcare Facilities.
Metro Rail & Electric Traction Networks.