A comprehensive soil resistivity survey is key to creating an effective earthing system, as inadequate or erroneous soil resistivity readings are likely to result in a flawed design. The types of system grounding normally used in industrial and commercial power systems are. Earthing systems design steps part one electrical knowhow. Principles and applications has been the goto text for gaining proficiency in the technological fundamentals of power system protection. Different types of protection for electrical systems and networks. The question, however, is how these systems can be made to be compatible with each other in order to ensure effective operation. Apr 03, 20 grounded conductor is an energized circuit conductor that is connected to earth through the system ground commonly referred to as the neutral grounding conductors. Equipment grounding conductor acts as a safeguard against insulation failure or faults in the other circuit conductors. Apr 03, 20 the path to ground from circuits, equipment, and enclosures shall be permanent and continuous groundingthere are two kinds of grounding.
A residually connected ground relay is widely used to protect mediumvoltage systems. The problem is formulated as a mixedinteger linear. Instructions ground protection systems ge industrial. A conductor used as an equipment grounding conductor shall be identifiable and distinguishable from all other conductors identification of conductors grounded conductor. Design and application considerations for each problem area are given to aid in setting the relay elements correctly. A transformer is always considered a separately derived system. There are two methods to accomplish this system of grounding, namely the low resistance grounding and high resistance grounding. Continuing in the bestselling tradition of the previous editions by the late j.
Ungrounded systems this system grounding arrangement is at the other end of the spectrum from solidlygrounded systems. Relays 5 to 12 test diagrams for systems with integral g. This system is a remote one, where the groundbed, or anode, is placed at a remote place, which may be at any corner of the tank farm, and is used to cathodically protect all buried metallic structures in the tank farm including the earthing grid for this system, all metallic structures must be bonded, either mechanically or. The actual ground current is measured by cts that are interconnected in such a way that the ground relay responds to a current proportional to the groundfault current. A system of ground clamps, ferrules, cluster bars and cables designed and suitable for carrying fault current as specified in astm f855. In this article, you will be able to cover the different electric protection methods, system and devices, grading and protection, overhead lines protection, power system protection, cables feeder protection, transformer protection, motor protection,generator protection, capacitor banks protection, bus bar protection, voltage. Electrical circuit or system grounding electrical equipment grounding electrical system grounding one conductor of the circuit is intentionally grounded to earth protects circuit from lightning, or other high voltage contact.
To understand the system voltage relationships with respect to system grounding, it must be recognized that there. Philosophy on design objectives and criteria equipment and recording considerations. The path to ground from circuits, equipment, and enclosures shall be permanent and continuous groundingthere are two kinds of grounding. Grounding analysis is performed by considering the metal parts. Electrical circuit or system grounding electrical equipment grounding electrical system grounding one conductor of the circuit is intentionally grounded to earth protects circuit from lightning, or other high voltage contact equipment grounding all metal. Sep 09, 2003 targeting the latest microprocessor technologies for more sophisticated applications in the field of power system short circuit detection, this revised and updated source imparts fundamental concepts and breakthrough science for the isolation of faulty equipment and minimization of damage in power system apparatus. Substation automation, system design and implementation apply theory to real system examples communication theory and practice on microprocessor. Advances in technology, such as the microprocessor and fiber optics, will continue to produce re. Shields is a comprehensive study guide for the design of industrial and commercial electrical power systems as dictated by neutralgrounding and groundfault protection practices. Primary and backup relay systems primary schemes are generally high speed schemes operate speed 1 cycle backup schemes can also be high speed but dont have to be. Protective devices associated with a high resistance system allows the system to continue working with the presence of a ground fault and send an alarm instead of tripping and open the associated protection. Two models can be used aby dividing the system in a number of segments, each. Understanding the importance of electrical grounding nec 250. The term ungrounded system is actually a misnomer, since every system is grounded through its inherent.
Mcgrawhills nec 2014 grounding and earthing handbook. Safe grounding system design for a photovoltaic power station. A welldesigned and installed ground network is invisible to the engineering staff. All of the power sources mentioned above except d are magneticallyoperated devices with windings. Corrosionpedia cathodic protection of earthed tank farms.
By extending emtps capabilities, the response of a grounding system to transient or other phenomena, can be computed using transmission line models 1,7. This is a discussion of the basic principles behind grounding systems and how grounding is related to safety and the effective operation of circuit protection devices such as fuses and circuit breakers. Maintenance grounding is a proven method for protecting electrical workers during mediumvoltage switchgear maintenance. Mcgrawhills national electrical code 2014 grounding and earthing handbook fully addresses the abovegrade grounding and belowgrade earthing issues related to article 250 of the 2014 national electrical code. Technique for grounding system design in distribution substation. The second part is concerned mainly with power system relaying communication. Introduction the attention given to the design and installation of a facility ground system is a key element in the dayto day reliability of the plant. Presented at the 69th annual georgia tech protective relaying conference atlanta, georgia april 29may 1, 2015 previous revised edition released october 2014. It describes the case of a large electrical generating station with a bare copper grounding grid, typical of late1960s construction practices. This practical guide features indepth discussions of each of the codes requirements, section by section, along with clear. While most systems today are limited by the number of parts you can preassemble, this simple, manual process allows the assembly of multiple components limited only by the length of the grounding bolt. Lewis blackburn, the fourth edition retains the core concepts at the heart of power system. M electrical cathodic protection issues in large generating.
Lewis blackburn, the fourth edition retains the core concepts at the heart of power system analysis. Targeting the latest microprocessor technologies for more sophisticated applications in the field of power system short circuit detection, this revised and updated source imparts fundamental concepts and breakthrough science for the isolation of faulty equipment and minimization of damage in power system apparatus. What would make a generator a separately derived system is if a transfer switch also switched the grounded conductor neutral. The codes shown are examples only and may not be current or accurate for your. Advanced techniques for analysing operation of protective relays and related interactions with the power system are discussed. The neutral on a wye system is a prime example of a grounded conductor. Electrical protection systems, devices and units electrical.
Weve expanded our partnership post glover now has an expanded partnership with rockwell automation to include encompass asiapacific. A marginal ground system, however, will cause problems on a regular basis. Power cable systems grounding tutorials and basics. This is the fourth generation hrg system from post glover and is the premier digital high resistance pulsing grounding system available. Shields is a comprehensive study guide for the design of industrial and commercial electrical power systems as dictated by neutral grounding and groundfault protection practices. Ul 467 grounding and bonding equipment standards catalog. Autoranging portable ground resistance and bond meter 10 mo to 20 ko the model r1lc is a ground resistance ohmmeter designed to measure grounding system resistance as well as soil resistivity, over ranges from 2o to 20 ko full scale. Facility and equipment grounding to enhance equipment. Technique for grounding system design in distribution. Inc is a unique company offering a wide range of experience and education in the area of power system operations, design, consultation and studies. Grounddistancerelay connections, 360 groundfault neutralizer, effect on line relaying, 321 to mitigate the effect of a fault, 2 grounding protective relay for trans former protection, 263 ground preference, 91, 108 ground resistance, 303 groundingtranaformer protection, 268 hsrmoniccurrent restraint, for distance relays. Protective relays provide the brains to sense trouble, but they are not able to open and isolate the problem area of power system.
Grounded system refers to a system where a conductor is grounded and is intended to or may carry current in the normal operation. A typical scheme for detecting a ground fault in a high resistance grounding system is. System grounding, or the intentional connection of a phase or neutral conductor to earth. Resistance grounding in an electrical system is defined as the use of a resistor as a grounding path between the neutral point of transformer or generator and the earth ground. Apr 19, 2018 cathodic protection of earthed tank farms in order to overcome corrosion and safety problems in tank farms, both cathodic protection and grounding systems need to be applied. Testing 3 test methods 3,4 test equipment 4 notes on testing 4 test diagrams for systems with g. The various protocols and network topologies used for protective relaying.
Temporary protective grounding equipment installed in a manner that bonds the ground source and the cables phase conductor and concentric neutral. Accordingly, the design of such protection systems must. This, combined with the fundamental concepts and applications of electric power systems protection make this book a good reference for anyone with interest in protection, automation and control. Protective relaying philosophy and design standards. Not an energized conductor under normal conditions. New approaches for maintenance grounding in mv switchgear. Some problem areas of ground fault detection are discussed, including system nonhomogeneity, zerosequence mutual coupling, remote infeed into highresistance faults, and system unbalances due to inline switching.
Protection systems contents description page general information 2 checklist for g. The main purpose of this work is the development of an optimization model for the design of the grounding grid in electrical substations. The purpose of this project is to give indept insight on resonant grounding methods, sources of ground current, ground current flow in the power system, and how each impacts protective relaying with a ground fault neutralizer used in resonant grounding. Industrial power system grounding design handbook john. Principles and applications, third edition power engineering willis hardcover technological advances and structural changes within the electric utility industry mandate that protection engineers develop a solid understanding of the related new technologies as well as of power system operations and economics in order. The overview of grounding system can protect damage from fault such as can save a human life and power system equipment. Without grounding, shields would operate at a potential considerably above ground. Delphi grounding systems offer easy, onestep preassembly of multiple wiring harnesses to one centrally located grounding base. A sturdy canvas carrying bag is supplied to ensure the operating components of the grounding kit remain clean and ready for service. System conditions dictate if this scheme has to be as fast as the primary scheme pjm2014 17 114. When mated with similarly rated products, the grounding kit operating components provide a fullyshielded, submersible, separable grounding system. An ungrounded system is a system where there is no intentional connection of the system to ground. Statistically, 9095% of all system shortcircuits are ground faults so this is an important topic. A safe and costefficient grounding system design of a 3 mwp photovoltaic power station according to ieee std 802000 is presented.
Pdf grounding system design in electrical substation. Modern grounding switches allow personnel to perform maintenance grounding with switchgear completely enclosed. Knowledge ofexperience with protective relaying and use of electrical equipment what to bring laptop with serial port or usbserial converter, serial cable. Protective relaying philosophy and design guidelines pjm. To identify any terminal which is intended on your mark for protection against electrical shock in case of a fault, or the terminal of a protective earth ground electrode. Multiple accurate soil resistivity readings should be done at various depths usually 3 depths across the. The main objective of this paper is guide the first step for someone who attends to design of grounding system before study in details later. Industrial power system grounding design handbook by j. The practices used in groundfault protection are described in a later section of this guide. Multiple accurate soil resistivity readings should be done at various depths usually 3 depths across the site.