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LZR-Series Neutral Grounding Resistor (NGR)
Low Resistance Grounding System

Low Impedance Grounding Equipment for Detecting Ground Fault Current of a Medium Voltage Generator or Transformer Neutral

SAFE RELIABLE EFFECTIVE GROUNDING

APT’s low impedance grounding Neutral Grounding Resistor and Reactor will reduce the stress and amount of damage to your power system equipment. They do this by controlling the magnitude of the ground fault currents.

When used in generator neutral, these devices will also limit the amount of the generator available Line to Neutral fault current below the design limits set by the NEMA MG1 generators design standard.
Additionally, APT Neutral Grounding Resistors and Reactors will reduce the magnitude of the harmonic currents. This circulates in the neutrals of paralleled generators due to the differences in the generator winding pitches, armature reaction, and other system conditions.

APT Neutral Grounding Resistors help switchgear sense that there is current in neutral/ground. The NGR’s help dissipate that current.

Voltage Ratings

2.4kV-15kV

Current Ratings

100A – 400A

Temperature Rise

1400°F (Maximum)

MV Part Number Configurator & Budgetary Pricing

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Neutral Grounding Resistor Core Features

Used in the neutrals of generators, transformers, and other rotating machines
Performs best when operated in a 120°F maximum ambient temperature, 0°F minimum ambient temperature, and an altitude 6000 feet or lower
Standard Enclosure includes:
- Filtered ventilation louvers
- NEMA 1/3R for indoor/outdoor applications
- Hot Dip Galvanized
- Cables: Bottom Entry/Exit
Enclosure Options:
- Aluminum, Stainless Steel (304 or 316)
- Powder coated ANSI 61 Gray or custom colors
- One or two connection bushings that can either be top or side mounted
LZR-P Option to accommodate tight lead time requirements and other site-specific specifications
Window Type or Bar Type Current Transformer, with secondary terminals available for field interconnection to the ground fault relay
Unfused or Fused Voltage Transformer
Maximum Dimensions: 40″W x 38″D x 28″H
Approximate Weight: 500 lbs.

Neutral Grounding Resistor Product Applications

Electric Utility & Manufacturing
Water Treatment Plants
Low Service Pump Stations
Healthcare
Data Centers
Hotel Resorts
Many more!

Product Literature

Engineering Bid Specifications

Installation Drawings & Diagrams

WE ARE HERE
TO SERVE YOU

We are committed to providing expert support and tailored power solutions. Contact our team today to find the right answers for your needs.

Our Service & Expertise

Advanced Power Technologies (APT) offers a full range of:

Intelligent power distribution systems
Low and medium voltage switchgear
Walk-in equipment buildings
And more!

We design and build our products in-house, based on how you would like it to be. APT has many different options to create the best and reliable switchgear for your power system.

APT will provide a comprehensive system commissioning and integration once we install our equipment. We will continue our ongoing support during the lifetime of the installation, including:

Field service upgrades
Retrofits

LZR-SERIES

Neutral Grounding Resistor (NGR)

2.4kV - 15kV Low Resistance Grounding System

Designed to limit ground fault current, protect critical equipment, and enhance personnel safety in medium-voltage electrical systems.

View Brochure Request a Quote View Specifications

Voltage Range

2.4kV - 15kV

Current Rating

50A - 400A

Duty Cycle

10 Seconds Standard

Applicable Standards

Project Dependent

Enclosures

NEMA 1, 3R & Custom

Designed

Custom Configurations

Key Specifications

Voltage

2.4kV - 15kV

Applicable Standards

Project Dependent

Current Rating

50A - 400A

Enclosures

NEMA 1, 3R & Custom

Duty Cycle

10 Seconds

Designed

Custom Configurations

Overview

The LZR-Series neutral grounding resistor limits ground-fault current by placing calculated resistance between the system neutral and ground.

By working with the system relays and other protective devices, the LZR-Series helps achieve reliable operation while reducing arc-flash energy and minimizing damage to equipment.

Ruggedly constructed and available in a wide range of configurations, the LZR-Series is suitable for indoor or outdoor installations in industrial, commercial, and utility applications.

Explore Configurations

Standard Construction

LZR-Series standard enclosure construction

01 Custom Voltage & Current Ratings
02 NEMA-Rated Protection
03 Hot Dip Galvanized Construction
04 Bottom Cable Entry and Exit

Final configuration may vary by project requirements.

Why It Matters

System Protection

Limits single-line ground-fault current and protects critical equipment.

Personnel Safety

Supports safer fault-current control.

Designed to Perform

Built, tested, and configured for your exact requirements.

Reliable Operation

Supports protective devices for dependable system operation.

How It Works

The LZR-Series limits ground-fault current by placing calculated resistance between the system neutral and ground. The system relays and other protective devices helps achieve reliable operation.

View Detailed Diagram Explore Configurations

Need Help Selecting the Right Configuration?

Not sure which voltage, enclosure, or options your application requires? Our sales team can help you select the right LZR-Series Neutral Grounding Resistor for your project.

Voltage Enclosure Monitoring Testing

Our team can help with:

Application review
Configuration recommendations
Customized solutions
Fast response from our sales team

Talk to a Product Specialist

Technical Specifications

Voltage: 2.4kV–15kV, 3Ø
Current Rating: 50A–400A
Application: Generator and transformer neutrals
Primary Function: Limits ground-fault current
Standard Enclosure: NEMA 1/3R indoor/outdoor
Construction: Rating and configuration dependent
Connection Options: One or two bushings
Monitoring Options: Window or bar-type CT

Generator Neutral Grounding

Controls ground-fault current.

Transformer Neutral Grounding

Applies resistance between neutral and ground.

Rotating Machines

For generators and other rotating equipment.

Paralleled Generator Systems

Helps reduce circulating harmonic currents.

Application suitability depends on system design and grounding requirements.

FAQ

What is a neutral grounding resistor?

The LZR-Series is a low-resistance neutral grounding resistor designed to limit ground-fault current in medium-voltage electrical systems.

How do I select the correct resistor?

Selection depends on the system voltage, desired current rating, duty cycle, enclosure, monitoring, and project-specific requirements.

What voltage range is available?

The LZR-Series is available for medium-voltage systems ranging from 2.4kV through 15kV.

Can a neutral grounding resistor be used outdoors?

Yes. Indoor and outdoor enclosure options are available, including NEMA 1, NEMA 3R, and custom configurations.

Are monitoring options available?

Monitoring options may include window or bar-type current transformers and other project-specific monitoring components.

Technical Resources

Ready to Get Started?

We are committed to providing expert support for your grounding system needs. Our team can help review voltage, current, enclosure, monitoring, and documentation requirements.

Contact our sales team today to discuss your application. We’ll help you find the right LZR-Series configuration for your system.

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LZR-Series Neutral Grounding Resistor (NGR) Low Resistance Grounding System