High Resistance Grounding
Overview

  • High Resistance Ground (HRG) systems are available for both 480V and 5kV systems and provide a high resistance path to ground. Most commonly used for testing distribution systems and locating ground faults for corrective action. These units can be constructed as stand alone cubicles or installed integrally into low voltage or medium voltage switchgear.
     
    High resistance grounding system grounds the neutral through a resistance which limits the ground fault current to a value equal to or slightly greater than the capacitive charging current of that system.

  • Ground-Gard high resistance grounding equipment consists of a group of devices coordinated and connected to provide a high resistance ground and ground fault detection for a power system. Major components of this system include:
     
    • UL Labeled Enclosures
    • Bank of Three Grounding Transformers (Delta Connected Systems)
    • Single Grounding Transformer (Wye Connected Systems)
    • Grounding Resistor
    • Device to Disconnect the Ground-Gard from the Power System
    • Metering and Control Devices
    • Pulsing System

  • A ground fault is detected by a contact-making voltmeter (MR). The meter-relay actuates a timer set for about five (5) seconds. This timer prevents alarming faults of a transient nature. If it times out, an auxiliary relay picks up and seals in through a reset button. Contacts of the auxiliary relay then energize whatever alarm or annunciator system desired by the user. Another auxiliary relay is connected to alarm if the control voltage fails or the ground is disconnected from the system.
     
    A normal operating sequence would be for an operator to acknowledge the alarm, find and clear the ground fault, and then reset the high resistance grounding system. 

  • Powell High Resistant Grounding systems are available as stand alone units or may be incorporated into any Powell switchgear solution.
     
    • No tripping of feeder breakers on occurrence of first ground fault
    • Minimum flash hazard to personnel during ground fault
    • Minimum arcing fault damage to equipment during ground fault regardless of fault location
    • Practical suppression of transient overvoltage due to arcing ground faults
    • Practical reduction of equipment damage due to high impedance faults

  • At Powell Project Management is a part of everyday life and every project. We see our role as making certain that your needs are incorporated into the design and schedule of every job, no matter how small.
     
    We fully understand that from the smallest Spare Parts order to the largest Integrated Packaged Solution your concerns are paramount. What is important to you is important to us. Your Project Manager provides you an entry into our full understanding of your project.
Specifications

  • Consider these features when considering a Powell High Resistance Ground system.
     
    • Positive Ground Fault Alarm
    • Traceable Signal to the Fault for Corrective Action
    • Available for 480V, 600V, 2400V, and 4160V Systems
    • Available for Delta or Wye Connected Systems
    • Can be Custom Designed as an Integral Part of Your Electrical System
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