Paul G. Cardinal

An expert system for computer generation of cable, conduit and tray schedules for industrial power and control systems

Integrated Design Systems (IDS) are the wave of the future in the Engineering and Construction industry. These systems use powerful relational database programs to allow the data from a single entry point to be the source information for several forms of data output. The high costs of relational database software, network hardware and development of the expert system programing which links the system together, limits those who can take advantage of IDS. For those who desire the increased productivity and higher quality control of a single entry point system, but do not require the full functionality of a complete IDS package, this paper discusses the development of a system, based on common dBase commands, which automatically generates electrical cable, conduit and tray schedules from information within an existing electrical load list database.Project Design Systems (PDS) are the wave of the future in the engineering and construction industry. PDS use powerful relational database programs to allow the data from a single entry point to be the source information for several forms of data output. The high costs of relational database software, network hardware and development of the expert system programing which links the system together, limits those who can take advantage of PDS. For those who desire the increased productivity and higher quality control of a single entry point system, but do not require the full functionality of a complete PDS package, this paper discusses the development of a system, based on common dBase commands, which automatically generates electrical cable, conduit and tray schedules from information within an existing electrical load list database.<<ETX>>

Generator Pitch and Associated Concerns When Paralleling Generators

Though a basic design element, generator pitch is a term often unfamiliar to users due to the extent of standardization within regions of the world. Because of standardization, pitch requirements may be omitted from generator specifications. Familiarization with generator pitch can therefore come as a crash course after equipment data sheets arrive for a generator of foreign construction. This paper will describe generator pitch along with other generator design criteria that affect output harmonics. For situations where it is impossible to achieve harmonic compatibility of sources, installation recommendations are provided that address control of harmonic driven circulating currents.

Automated coordination programs do not make correct results automatic

The availability of computer programs which aide in protective device coordination studies has led to the assignment of coordination problems to those who are computer literate rather than protection literate. For those put in this unfortunate situation, some of the finer points of time current coordination are presented which are often not learned until after the news of that first false trip. This paper is intended as an addendum to, rather than a replacement for a typical time current coordination seminar. It covers: delta-wye transformers, instantaneous relays, protective device tap ranges, transformer damage curves, and combination starters.

Low Cost for Voltage Heater Control: An Affordable Evolution Using Variable Voltage Transformers

Power electronic devices are the standard solution for lowvoltage (LV) heater control; however, cost and harmonic issues are amplified for medium-voltage (MV) heater applications. To provide an MV alternative at a significantly lower cost, this article details modifications and testing that will evolve part-range and load-tap-changing voltage regulators into full-range variable voltage transformers (VVT) for MV heater control. From the initial minor modifications that converted autotransformers into 16-tap isolation transformers, the development moves on to the inclusion of secondary base windings that bring 32 taps into play for refined control. Three-phase solutions and the addition of MV interrupters from the utility industry provide an economical solution for a stand-alone MV heater operation that avoids the harmonic issues of other heater control technologies.

Variable voltage transformers for medium voltage heater control

Power electronic devices are the standard solution for low voltage heater control, however, cost and harmonic issues are amplified for medium voltage heater applications. To provide a medium voltage alternative at significantly less cost, this paper details modifications and testing that evolved part range, load tap changing, voltage regulators into full range variable voltage transformers for medium voltage heater control. From the initial minor modifications that converted autotransformers into 16 tap isolation transformers, the development moves on to inclusion of secondary base windings that bring 32 taps into play for refined control. Three phase solutions and addition of medium voltage interrupters from the utility industry round out an economical solution for stand-alone, medium voltage heater operation that avoids the harmonic issues of other heater control technologies.

Grounding (bonding to earth)

Returning to basics, grounding is bonding to earth. While grounding electrodes are the only true bonds to earth, the term “grounding” has been traditionally applied when bonding to extended conducting bodies such as the ground bus in an electrical panel. That tradition is presently under fire with suggestions that anything other than the connection to grounding electrodes is bonding rather than bonding to earth. Beyond semantics, the term “bonding” alone compared to “bonding to earth” presents a clear omission which is the reference to earth. This paper challenges that omission presenting the multifaceted approach for reduction of electrical hazards provided by bonding to earth rather than simply bonding.

Open door arc flash calculations related to closed-door applications

NFPA 70E defines Incident Energy Analysis as “A component of an arc flash hazard analysis used to predict the incident energy of an arc flash for a specified set of conditions.” Conditions presently specified are for hazards that exist when energized electrical conductors or circuit parts are exposed. From a letter of the law perspective, address of closed door Arc Flash hazards requires either the use of a calculation for other than specified conditions or use of equipment for a purpose for which it lacks certification. Practically, combining information from existing calculations with knowledge of existing equipment certification testing can improve understanding of closed door hazards. As a starting point, calculated calories per centimeter squared are translated into equivalent force. Similar conversions are applied to energies of standard device functions such as interruption of available fault currents. Estimated forces are then compared to present enclosure certifications to produce expected closed door hazards based on present incident energy analysis techniques.

IEC grounding terminology related to typical North American installations

IEC grounding terminology provides concise descriptions of system configurations requiring a sentence or more using familiar North American verbiage. However, without relation to known systems, simple representations using only five letters of the alphabet join the list of meaningless acronyms that clutter our life. This paper begins with definitions of the five letters used to describe IEC grounding systems and follows with wiring diagrams that include North American terminology. Examples of global configuration applications are included. System variations are presented along with strengths and weaknesses to provide additional understanding of both grounding and grounded conductors.

Safe Installation of Metal Light Poles per NEC or NESC

Utility environments impose electrical installation complications beyond those of residential, commercial or even industrial power facilities covered by the national electrical code (NEC). Outdoor lighting circuits, though having circuit voltages similar to typical NEC installations, must face transferred potential, adjacent high voltages and lightning protection issues that those responsible for the NEC consider outside the scope of that document. This paper will look into the challenges of utility environments in hopes of providing a better understanding of the demands of outdoor lighting installations.