TRANSMISSION LINES DESIGN and ELECTRICAL ENGINEERING HUB

The life of a lead-acid storage battery depends on the use to which it is put and on the care it receives. With good care, it will last several years; with little or no care, it may be ruined in a month. The important rules for battery care are as follows: 1. Test storage batteries periodically. Always wear eye and clothing protection to shield yourself from battery acid. 2. If a battery is completely discharged, recharge it immediately. 3. When charging a battery, select a charging rate consistent with the time available for charging. When time is available, use the normal rate indicated in the product manufacturer’s literature. 4. If it is necessary to charge a battery at a very high rate, keep a careful check on the temperature of the electrolyte and never let it exceed 110°F. If cells release gas freely, reduce the charging rate to the normal rate. 5. Never try to charge batteries to a definite specific gravity. Maintain the charge until the same specific gravit...

More than 500 nuclear power plants operate around the world. Close to 300 operate pressurized water reactors (PWRs), more than 100 are built with boiling-water reactors (BWRs), about 50 use gas-cooled reactors, and the rest are heavy-water reactors. In addition a few fast breeder reactors are in operation. These reactors are built for better utilization of uranium fuel. The modern nuclear plant size varies from 100 to 1200 MW. Pressurized Water Reactor The general arrangement of a power plant with a PWR is shown in Fig. 59.8(A). The Reactor heats the water from about 550 to about 650° F. High pressure, at about 2235 psi, prevents boiling. Pressure is maintained by a pressurizer, and the water is circulated by a pump through a heat exchanger. The heat exchanger evaporates the feedwater and generates steam, which supplies a system similar to a conventional power plant. The advantage of this two-loop system is the separation of the potentially radioactive reactor coo...

There are three primary color transmission standards in use today: • NTSC (National Television Systems Committee): Used in the United States, Canada, Central America, most of South America, and Japan. In addition, NTSC is used in various countries or possessions heavily influenced by the United States. • PAL (Phase Alternation each Line): Used in England, most countries and possessions influenced by the British Commonwealth, many western European countries and China. Variation exists in PAL systems. • SECAM (Sequential Color with [Avec] Memory): Used in France, countries and possessions influenced by France, the USSR (generally the former Soviet Bloc nations), and other areas influenced by Russia. The three standards are incompatible for a variety of reasons (see Benson and Whitaker, 1991). Television transmitters in the United States operate in three frequency bands: • Low-band VHF (very high frequency), channels 2 through 6 • High-band VHF, channels 7 through 13 ...

Frequency-modulation (FM) broadcasting refers to the transmission of voice and music received by the general public in the 88- to 108-MHz frequency band. FM is used to provide higher-fidelity reception than is available with standard broadcast AM. In 1961 stereophonic broadcasting was introduced with the addition of a double sideband suppressed carrier for transmission of a left-minus-right difference signal. The left-plus-right sum channel is sent with use of normal FM. Some FM broadcast systems also include a subsidiary communications authorization (SCA) subcarrier for private commercial uses. FM broadcast is typically limited to line-of-sight ranges. As a result, FM coverage is localized to a range of 75 mi (120 km) depending on the antenna height and ERP. Frequency Allocations The 100 carrier frequencies for FM broadcast range from 88.1 to 107.9 MHz and are equally spaced every 200 kHz. The channels from 88.1 to 91.9 MHz are reserved for educational and noncommercial ...

After a disturbance, due usually to a network fault, the synchronous machine’s electrical loading changes and the machines speed up (under very light loading conditions they can slow down). Each machine will react differently depending on its proximity to the fault, its initial loading and its time constants. This means that the angular positions of the rotors relative to each other change. If any angle exceeds a certain threshold (usually between 140° and 160°) the machine will no longer be able to maintain synchronism. This almost always results in its removal from service. Early work on transient stability had concentrated on the reaction of one synchronous machine coupled to a very large system through a transmission line. The large system can be assumed to be infinite with respect to the single machine and hence can be modeled as a pure voltage source. The synchronous machine is modeled by the three phase windings of the stator plus windings on the rotor representing the f...

Load Flow (Power Flow) The need to know the flow patterns and voltage profiles in a network was the driving force behind the development of load flow programs. Although the network is linear, load flow analysis is iterative because of nodal (busbar) constraints. At most busbars the active and reactive powers being delivered to customers are known but the voltage level is not. As far as the load flow analysis is concerned, these busbars are referred to as PQ buses. The generators are scheduled to deliver a specific active power to the system and usually the voltage magnitude of the generator terminals is fixed by automatic voltage regulation. These busbars are known as PV buses. As losses in the system cannot be determined before the load flow solution, one generator busbar only has its voltage magnitude specified. In order to give the required two specifications per node, this bus also has its voltage angle defined to some arbitrary value, usually zero. This busbar is kno...

DESCRIPTION Specification Nominal Voltage : 69 kV Manufacturer : xxx (your choice) Type: SSB-III-72.5 Quantity: Construction: Horizontal Double Side Break Disconnector Installation: Horizontal/Vertical Poles : 3 pole disconnect Operating Mechanism: Motor Operated Drive (for Outdoor) or Manual   (Depende sa inyo) Design Voltage: 72.5 kV B.I.L. : 350 kV Operating Frequency: 60 Hz Continuous Current : 2,000.00 A Momentary Current : 51 kA  (ANSI) Short Circuit Capacity: 40 kA Peak Withstand Current: 100 kA (IEC) Accessories: Complete with 2 insulators per pole, Steel Channel, IEC std. Fittings

Electrical power systems are, in general, fairly complex systems composed of a wide range of equipment devoted to generating, transmitting, and distributing electrical power to various consumption centers. The very complexity of these systems suggests that failures are unavoidable, no matter how carefully these systems have been designed.  The feasibility of designing and operating a system with zero failure rate is, if not unrealistic, economically unjustifiable. Within the context of short-circuit analysis, system failures manifest themselves as insulation breakdowns that may lead to one of the following phenomena: — Undesirable current flow patterns — Appearance of currents of excessive magnitudes that could lead to equipment damage and downtime — Excessive overvoltages, of the transient and/or sustained nature, that compromises the integrity and reliability of various insulated parts — Voltage depressions in the vicinity of the fault that could adversely affect th...

For low-voltage circuit protection in the U.S., circuit breaker designs and tests are based on the requirements of three standards organizations; the American National Standards Institute (ANSI), Underwriters Laboratories (UL), and the National Electrical Manufacturers Association (NEMA). The two classifications of circuit breakers these organizations defined are as follows: - Molded-case circuit breaker class - Low-voltage power circuit breaker class Three types of circuit breakers are based on the two classifications above. The classifications themselves lend their names to the first two of the three types, while the third type, derived from the molded-case circuit breaker class, is known as an insulated-case circuit breaker. The three types of circuit breakers are as follows: Molded-case circuit breakers (MCCBs) Low-voltage power circuit breakers (LVPCBs) Insulated-case circuit breakers (ICCBs) The following are some of the salient features of these types...

Static electrification (SE) in transformers is an interfacial phenomenon, which involves oil, paper and transformer board. Its physical mechanism involves a source of charge and region of excessive charge accumulation. Extensive investigations about this phenomena have been made during recent years. 25 When oil is forced through the tank and coolers, it acquires an electrostatic charge, i.e. it contains an equal number of positive and negative ions. When the oil passes the paper and solid insulation in the windings, the insulation becomes negatively charged and the oil positively charged with the charge separation occurring at the oil-insulated interface (Fig. 6.16). The earliest reports on this phenomenon were in the 1970s from Japan, where number of h.v. large transformer failures occurred. And later quite a few SE-related incidents were also reported in the USA and other countries. It is believed that transformers of large rating (e.g. >100MVA) are most likely...

Many electric utilities have employed equipment condition monitoring (ECM) to maintain electric equipment in top operating condition while minimizing the number of interruptions. With ECM, equipment operating parameters are automatically tracked to detect the emergence of various abnormal operating conditions. This allows substation operations personnel to take timely action when needed to improve reliability and extend equipment life. This approach is applied most frequently to substation transformers and high-voltage electric supply circuit breakers to minimize the maintenance costs of these devices, to improve their availability, and to extend their useful life. Equipment availability and reliability can be improved by reducing the amount of off-line maintenance and testing required and by reducing the number of equipment failures. To be truly effective, equipment condition monitoring should be part of an overall condition-based maintenance strategy that has been...

Since its first proposal in 1966 the economics behind optical fiber technology have changed radically. The major components within the communications system comprise the fiber (and the resulting cable), the connections and the opto-electronic conversion equipment necessary to convert the electrical signal to light and vice versa. In the early years of optical transmission the relatively high cost of the above items had to be balanced by the savings achieved within the remainder of the system. In the case of telecommunications these othervsavings were generated by the removal of repeater/regenerator stations. Thus the concept of ‘break-even’ distance grew rapidly and was broadly defined as the distance at which the total cost of a copper system would be equivalent to that of the optical fiber alternative. For systems in excess of that length the optical option would offer overall cost savings whereas shorter-haul systems would favour copper – unless other technical factors overr...

The diesel, or compression-ignition, engine is one of the four principal types of internal combustion engine; that is, it is a machine that converts the chemical energy released from the burning of a fuel in an internal combustion chamber directly to mechanical energy. Although the diesel is a reciprocating machine, its mechanical energy is transferred from the engine by means of a rotating shaft that may be used to drive other mechanical, hydraulic, pneumatic, or electrical machines and equipment. Worldwide there are many diesel engines manufacturers, and the engine types available range from extremely powerful low-speed two-stroke engines of up to 70 MW to high-speed automotive-type engines to low-power portable units of less than 2 kW (1.492 hp). In industrial and marine applications, diesel engines are used mainly in the generation of electrical power, both ac and dc. In this article the topics addressed are the diesel engine itself and the production of ac power by die...

The main advantages of using diesel driven electrical power generators are (not in rank order): 1. Performance.  Diesel engines normally have high thermal efficiencies, in the region of 40% and higher, almost regardless of their size. Some current state-of-the-art engines can achieve efficiencies over 50%, and engine manufacturers have forecast efficiencies as high as 60% by the twenty-first century. 2. Maintenance.  Diesels represent mature and well-developed technology and are comparatively easy to maintain on site without the need for fully skilled personnel except for certain nonroutine tasks. 3. Durability and Reliability.  Diesels have long lifetimes in the range, on average, of at least 20 to 25 years, and they can operate 7000 to 8000 h per year and in some cases up to 12,000 h between regular major overhauls. 4. Fuel Efficiency.  In most power-generation applications, diesels have the most competitive fuel consumption rates, and between half-load ...

Safety systems protect life and property from damage or loss due to accidents. For equipment, the degree of protection should be based on the value and criticality of the facility. Personnel safety is covered rigorously in the NEC and many other standards. Defining this degree requires an in-depth knowledge of the installation and its function. The following questions should be considered when designing these systems: a) How long will it take to replace the equipment and at what cost? b) Can the function of the facility be performed elsewhere? c) Loss of what key component would result in operation interruptions? Safety systems can be as simple as a manually operated emergency power-off button, or as complex as a fully interlocked system. However, the more complex a fully integrated system becomes, the higher the probability of system confusion or failure. Typical systems include the following functions: — Smoke and fire protection — Environmental control ...

Road vehicles emit significant air-borne pollution, including 18% of America’s suspended particulates, 27% of the volatile organic compounds, 28% of Pb, 32% of nitrogen oxides, and 62% of CO. Vehicles also release 25% of America’s energy-related CO2, the principle greenhouse gas.  World pollution numbers continue to grow even more rapidly as millions of people gain access to public and personal transportation. Electrification of our energy economy and the rise of automotive transportation are two of the most significant technological revolutions of the twentieth century. Exemplifying this massive change in the lifestyle due to growth in fossil energy supplies. From negligible energy markets in the 1900, electrical generation now accounts for 34% of the primary energy consumption in the United States, while transportation consumes 27% of the energy supply. Increased fossil fuel use has financed energy expansions: coal and natural gas provide more than 65% of the energy used ...

A number of types of security challenges to which SCADA systems may be vulnerable are recognized in the industry. The list includes: • Authorization violation: an authorized user performing functions beyond his level of authority • Eavesdropping: gleaning unauthorized information by listening to unprotected communications • Information leakage: authorized users sharing information with unauthorized parties • Intercept/alter: an attacker inserting himself (either logically or physically) into a data connection and then intercepting and modifying messages for his own purposes • Masquerade (“spoofing”): an intruder pretending to be an authorized entity and thereby gaining access to a system • Replay: an intruder recording a legitimate message and replaying it back at an inopportune time. An often-quoted example is recording the radio transmission used to activate public safety warning sirens during a test transmission and then replaying the message sometim...

Investigations of threats to corporate computer hardware and software systems traditionally have shown that the greatest number of attacks come from internal sources. Substation control systems and IEDs are different in that information about them is less well known to the general public. However, the hardware, software, architecture, and communication protocols for substations are well known to the utilities, equipment suppliers, contractors, and consultants throughout the industry. Often, the suppliers of hardware, software, and services to the utility industry share the same level of trust and access as the utility individuals themselves. Consequently, the concept of an insider is even more encompassing. A utility employee knows how to access the utility’s computer systems to gather information or cause damage, and also has the necessary access rights (keys and passwords). The utility must protect itself against disgruntled employees who seek to cause damage as well as e...

Measurements are normally carried out using the Wenner method and the data is used to arrive at a representative soil model for the site. Whilst the measurements would best be carried out in representative weather conditions, this is clearly not always possible, so allowance for seasonal effects may need to be made in the model. This would normally be done by modifying the resistivity and/or depth of the surface layer. Some typical soil resistivity values are shown in Table 8.2.   Measurements are taken for a range of probe separations, each of which is a general indicator of the depth to which the value applies. Measurements in a number of directions would be taken and averaged values (excluding obvious errors) for each separation distance would be used to derive the initial soil model. A number of computer programmes are commercially available and used to translate the data into a representative soil model. It is useful to have both the average model and the dat...

Choosing the most appropriate method of cooling for a particular application is a common problem in transformer specification. No clear rules can be given, but the following guidance for mineral oil-immersed transformers may help. The basic questions to consider are as follows: 1. Is capital cost a prime consideration? 2. Are maintenance procedures satisfactory? 3. Will the transformer be used on its own or in parallel with other units? 4. Is physical size critical? ONAN This type of cooling has no mechanical moving parts and therefore requires little, if any, maintenance. Many developing countries prefer this type because of reliability, but there is an increasing cost penalty as sizes increase. ONAF A transformer supplied with fans fitted to the radiators will have a rating, with fans in operation, of probably between 15% and 33% greater than with the fans not in operation. The transformer therefore has an effective dual rating under ONAN and ONAF conditions. ...

Three phase windings of transformers will normally be connected in a delta configuration, a star (wye) configuration, or, less commonly, in an interconnected star (zig-zag) configuration as shown in Fig. 14.16. The vector grouping and phase relationship nomenclature used is as follows: • Capital letters for primary winding vector group designation. • Small letters for secondary winding group designation. • D or d represents a primary or secondary delta winding. • Y or y represents a primary or secondary star winding. • Z or z represents a primary or secondary interconnected star winding. • N or n indicates primary or secondary winding with an earth connection to the star point. • Numbers represent the phase relationship between the primary and secondary windings.  The secondary to primary voltage displacement angles are given in accordance with the position of the ‘hands’ on a clock relative to the mid-day or twelve o’clock position. Thus 1 (representing one o...