Equipment Grounding Research Articles

System Grounding, Protection, and Detection for Cement Plants

Safety of personnel and equipment requires proper attention to power system and equipment grounding. The National Electrical Code, MSHA, IEEE, ANSI, and federal, state, and local codes contain regulations or recommendations on system and equipment grounding. Proper grounding practice can be achieved with several different methods and combinations of equipment. The use of ``portable'' equipment in quarries requires specific grounding method and ground check monitoring. Current practice and recommendations on ground fault detection and protection in modern cement plants and associated quarries are discussed.

Grounding for Emergency and Standby Power Systems

The basic functions of system and equipment grounding is presented, fundamental grounding requirements for service-supplied and separately derived power systems which operate at 600 V or less are discussed. Several grounding arrangements for alternate power supplies are also discussed and graphically illustrated. The grounding requirements are primarily derived from the National Electrical Code, NFPA No. 70-1978. The paper is intended to be the basis for a new chapter on grounding in the next edition of IEEE Standard 446-1974, Recommended Practice for Emergency and Standby Power Systems.

Equipment Grounding for Reliable Ground-Fault Protection in Electrical Systems Below 600 V

Equipment grounding is one of the most important, but least understood, requirements for reliable ground-fault protection. This paper defines the basic objectives of equipment grounding and analyzes the role of equipment grounding conductors in providing ground-fault protection for electrical systems below 600 V.

Problems with Large Ground Fault Currents in Utility Substations in or near Industrial Sites

One of the prime functions of equipment grounding is for safety to life and property. In designing an industrial power system that obtains any energy from a utility with a high ground fault current capability, it may be advisable to isolate the industrial and utility ground grids for safety reasons. A review of present practices as well as suggested modifications with an actual design example is presented.

A Review of Lightning Protection and Grounding Practices

Guides are presented to facilitate proper economic lightning protection of industrial power system component arrangements. Basic concepts of the traveling wave nature of lightning are included to enhance understanding of protective practices as they have developed and emphasize the need for careful adherence to approved practices in critical areas. The grounding treatment is very brief, being limited to the most salient considerations of equipment grounding in relation to the overall lightning protective system and the ground fault protective system. The paper is referenced throughout to current industry standards, application guides, and codes.

Important Functions Performed by an Effective Equipment Grounding System

The equipment grounding system concerns itself with the interconnection and grounding of nonelectrical conducting material which either encloses or is adjacent to energized electric power conductors. Its purpose is to assure that the building containing the electrical system, or the occupants of that building, are not subjected to a dangerous or objectionable environment condition incidental to the use of electrical power. The items of chief concem include: 1) freedom from electric-shock exposure to building occupants; 2) freedom from exposed sparking, arcing, flashing, or other fire ignition origin incident to operation of the electric power system; and 3) freedom from unnecessary electrical noise within the building space resulting from the presence of the electric power system.

Grounding and Electrical Leakage of Photo Therapy Equipment

I am the director of the Bio Electronics Lab at Wilson Memorial Hospital. We have a safety program in which electrical leakage on all electrical and electronic equipment is checked. Our standards are set in accordance to the American Heart Association at 5 microamps. This brings me to the purpose of this letter. We received an Air Shields photo therapy unit which is used in the prevention and treatment of neonatal hyperbilirubinemia. This lamp has a leakage of 70 micro-amps when it is ungrounded.

Proper Grounding Can Improve Reliability in Low-Voltage Systems

Safety and reliability of electric distribution systems depend on many factors, including proper grounding. Correct functioning of ground fault relays depends on carefully designed busway housings and conduit connections. Busway housings are recommended as the preferred equipment grounding means because they achieve a low voltage drop value with little danger of electric shock. Eleven specific suggestions are made in an effort to improve the safety and reliability of low-voltage systems.

Portable Safety Grounding Equipment Tests

The basic principle of safety grounding for the protection of workmen must be complemented by adequate grounding devices. Because of the great importance of these devices their adequacy should be proved by tests whenever 1) their design is changed although the change supposedly is an improvement; 2) system condition changes have accumulated beyond previously established limits; and 3) the slightest doubt about the reliability of a particular design has arisen.

Transurethral electrocautery procedures in patients with cardiac pacemakers

Three patients with cardiac pacemakers underwent four transurethral electrocautery procedures, without pacemaker interference. Electrical interference which could potentially cause cardiac arrhythmias was prevented by utilizing a well-shielded cardiac pacemaker, by proper grounding of all medical electronic equipment in use on or near the patient, and by keeping the electrocautery circuit below the pacemaker by low placement of the electrocautery ground plate. Additional safety precautions included maintenance of a normal blood volume and cardiac monitoring with an external pacemaker-defibrillator cardioscope.

Transurethral Electrocautery Procedures in Patients With Cardiac Pacemakers

Three patients with cardiac pacemakers underwent four transurethral electrocautery procedures, without pacemaker interference. Electrical interference which could potentially cause cardiac arrhythmias was prevented by utilizing a well-shielded cardiac pacemaker, by proper grounding of all medical electronic equipment in use on or near the patient, and by keeping the electrocautery circuit below the pacemaker by low placement of the electrocautery ground plate. Additional safety precautions included maintenance of a normal blood volume and cardiac monitoring with an external pacemaker-defibrillator cardioscope.

Successful Cardiac Monitoring

Successful monitoring requires—in addition to a working knowledge of electrocardiography—the following conditions: 1. Patient cooperation with frequent reassurance supplied by the nurse to patient and family. 2. Meticulous attention to skin beginning with cleanliness, hair removal, and daily alertness for signs of irritation and other complications. 3. Close contact between skin and electrode. 4. Adequate amounts of conductive medium. 5. Correct positioning of electrodes. 6. Correct grounding of equipment. 7. Unstated but implied is the fact that the nurse is also responsible for careful handling of the machines in order to preserve them for continued use. 8. Successful monitoring requires that the patient may progress away from use of the monitor without undue dependency. 9. Most important of all, successful monitoring must be conducted by a skilled, responsible nurse, eager to learn and ever alert both to the limitations and the potential of the use of monitors for the improvement of patient care.

Grounds, grounds, and more grounds

This paper discusses the need for proper grounding of electrical equipment from the standpoint of safe ty and performance. Seventeen diagrams are em ployed to illustrate the most important points. The discussion follows a fundamental vein in illus trating the proper connections of electrical apparatus to specifically avoid difficulties from common im pedances and "ground loops." Some of the many so-called grounds that are en countered in instrumentation are illustrated and defined according to function, in an attempt to clar ify what appears to be a somewhat confusing array of grounds. A computer grounding system is illus trated, as is a so-called hub ground method of in tegrating several computers (or other devices) into a compatible system. Emphasis is placed on the interconnection of elec trical devices, and attention is called to the need for thought concerning the circuit(s) formed by the casual treatment that is often given to such appar ently simple things as ground connections. This paper was written to provide information for operators who do not have specific electrical back grounds, and as a reminder to the electrical prac titioner that the most important connection of all is frequently the one called ground. "Ground," with its many connotations and impli cations, seems to raise some degree of confusion whenever it appears. There are grounds and grounds and grounds such as: signal ground, shield ground, power ground, relay ground, etc. This paper will at tempt to clarify this situation by examining the case from the ground up (wherever that is).

Hydrogen-sensitive, platinum-tipped electrode in the diagnosis of left to right shunts: Practical application

A new technic, utilizing a hydrogen-sensitive, platinum-tipped wire electrode introduced percutaneously via a No. 18 Cournand needle into the brachial vein and flow-directed into the right heart chambers and pulmonary artery, has greatly simplified the detection of left to right intracardiac shunts. The position of the electrode is identified by intracavitary electrocardiographic monitoring. Electrical potential, created by contact of inhaled hydrogen with the platinum tip, produces characteristic electrocardiographic deflections when left to right shunts are present. Two hundred and four catheterizations in 182 patients screened for possible left to right shunts yielded 86 positive, 115 negative and 3 equivocal shunt curves. Fifty-three instances have been confirmed by conventional cardiac catheterization technics or surgery, or by both. No definite false positive curves were obtained other than from the easily identified pulmonary wedge position. In 5 patients false negative curves were obtained from the proper chamber; however, in each instance positive curves were recorded from one chamber distally. This technic can be performed as an outpatient procedure in 15 to 30 minutes without discomfort except for venipuncture. Minor complications observed were brief supraventricular arrhythmia (3), multiple extrasystoles (2), transient difficulty in electrode dislodgment (2), and intracavitary knotting (2). No major complications have occurred. Caution is expressed regarding proper grounding of all electrical equipment to prevent electrically induced ventricular fibrillation. The potential hazard of a knot in the wire electrode embracing a papillary muscle or chorda tendinea suggests the need of ready access to an experienced cardiac surgeon. The procedure presents a simple, reliable and reasonably safe method for determing left to right shunts, both preoperatively and postoperatively, and often obviates the need for major catheterization.

Grounding of portable electric equipment used in dental offices

Grounding of portable electric equipment used in dental offices

Positive-Polarity Grounding of Direct Current Supply Requirements In Mining Traction Systems★

Abstract Serious corrosion of mine traction systems using positive-polarity grounding of direct current supply equipment is described. Abnormally increased costs from excessive trolley insulator failures and a safety hazard resulting from possible formation of pure metallic sodium or potassium in corrosion products are reported. As a consequence of these conditions, Tennessee Coal and Iron Division of U. S. Steel Corporation has converted the only two of its mines in which the traction systems were designed for positive-polarity grounding of negative-polarity trolleys. Reasons for the installation in mines of positive-polarity systems are given. Illustrations show how the corrosive electrolysis destroys the rock in which trolley supports are fastened. Tests indicate the presence of pure sodium or potassium in corrosion products. These metals will cause skinburns and when bits of the crusty deposit formed on the insulator fell into pools of water on the mine floor an explosive reaction accompanied by flame occurred. The extent of possible economic effects of these corrosive reactions on the mine transport systems are given.

Grounding, bonding, and lightning protection in oil refineries and chemical plants

Discussions of grounding equipment, grounding for protection against lightning, static charges, and grounding systems and corrosion are presented, and various aspects of grounding practice in the oil industry are reviewed.

Grounding of portable electric equipment

The new requirements affecting the use of portable electric equipment in the National Electrical Code, 1953 revision, are presented and discussed. Portable appliances, tools, and lighting equipment are included.

Equipment grounding for industrial plants

After pointing out what an important factor no grounding or inadequate grounding has been in electrical work injuries, the components of an equipment grounding system are discussed. Then the grounding of power station and distribution equipment, stationary utilization equipment, and portable equipment are considered.

Safety aspects of grounding portable equipment

Requirements of the Underwriters' Laboratories relating to the grounding of portable equipment are based on rules of the National Electrical Code, which is basically rules covering the installation of electric equipment in buildings. Part of the Laboratories' function is to determine that the listed electrical products can be installed in accordance with the Code's rules.