High-Resistance Grounding (HRG) of Industrial and Commercial Power System
Presented by: Dev Paul
Date: Thurs May 9, 1pm-5pm
Location: Fairmont Palliser Hotel, 133 9 Ave SW, Calgary, Alberta
Register in advance or on site: https://events.vtools.ieee.org/m/197631 Discounted online advance registration is open until May 8.
This tutorial is intended for both the experienced engineers much familiar with the HRG design as well as for the younger engineers starting their career in the power system design. How such an HRG design enhances safety of maintenance personnel and minimizes equipment hazard will be the main focus once the instructor provides clarifications on the fundamentals of HRG design.
One of the most confusing and challenging technical information of using HRG design is the flow of system charging current directions during phase-ground fault condition. This tutorial will go in details of this system charging current and related capacitive component of the ground fault current during fault condition.
Ground fault current has both the magnitude and the phase angle with respect to the voltage responsible for the ground fault current flow. This appears to be overlooked which caused published literature showing inconsistent power factor of the ground fault current for the HRG design. Also the word charging current appears to be causing confusion to application engineers who argued with the presenter that the charged capacitance between the power system components to ground becomes generators to provide capacitive component of fault current during phase-ground fault conditions. Presenter will provide brief and concise clear understanding of this “system charging current” and its flow during normal operation and during phase to ground fault condition.
For clarification purposes, the tutorial will include three-line presentation of a MV power system requiring HRG design to explain how system charging current flows in the reverse direction in the two un-faulted phase conductors before this current returns to the faulted phase to ground location. Clearly; this capacitive current flow towards the power system neutral in the two un-faulted phases in the reverse direction to the system charging current flow under normal power system operations. Upon reaching the system neutral this current traverses by the faulted phase conductor to the phase to ground fault location. At the power system neutral, the currents in the two un-faulted phases are added together by phasor diagram such that it becomes equal to total system charging current. By Kirkoff current law, current entering into the neutral (-3ICO) becomes 3ICO. This is how in the fault current phasor diagram, system charging current is presented as 3ICO, whereas capacitive component of the fault current are presented as -3ICO such that the two currents has 180° phase angle difference.