ALTERNATING CURRENT SYSTEMS[1,531] to 1,586
Advantages of the alternating current—classification of systems—vector summation; examples—forms of circuit: series, parallel, parallel series, series parallel—transformer systems: individual transformers; transformation at distribution centers—single phase system; two wire transmission and three wire distribution; objections to single phase systems; advantages—monocyclic system—two phase systems: adaptation; ordinary voltages used; two phase three wire system; two phase five wire system—three phase systems: six wire; four wire; three wire; connections: star, delta, star delta, delta star; evolution of three wire system; pressure and current relations; connection of transformers; open delta connection—change of frequency—Schaghticoke-Schenectady transmission line—transformation of phases: three to one, three to two, two to six, and three to six phase—Scott connection for transforming from three to two phase—three to two phase with three star connected transformers—economy of a.c. systems—relative weights of copper required for polyphase systems—aermotor towers of Southern Power Co.—choice of voltage—usual transmission voltages—diagram of three phase distribution—mixed current systems; usual d.c. pressure on traction lines; use of mixed systems.
AUXILIARY APPARATUS[1,587] to 1,588
Classification of auxiliary devices: switching devices, types—current or pressure limiting devices, types—lightning protection devices, types—regulating devices, types—synchronous condensers, types—indicating devices.
SWITCHING DEVICES[1,589] to 1,612
Definition of a switch—behaviour of the current when the circuit is broken—points on design—installation of single throw and double throw switches—plug switches—forms of break: open, enclosed, fuse, horn, oil—disconnecting switches—pole top switches—horn break switches—motor starting switch—oil switches; nature of an oil break—remote control oil switches—motor operated switches—rupturing capacity of oil switches—float switches.
CURRENT AND PRESSURE LIMITING DEVICES[1,613] to 1,676
Necessity for these devices; steam analogy—fuses: advantages and disadvantages; types: plug, cut out, expulsion, no arc, magnetic blow out, quick break fuse, etc.—metal used—current limiting inductances: construction, location—circuit breakers: progressive breaking of the circuit; carbon contacts—automatic features: overload trip, underload trip, low voltage trip, auxiliary circuit trip—relays: adaptation; classification: protective, regulative, communicative, a.c. and d.c., circuit opening, circuit closing, primary, secondary, overload, underload, over voltage, low voltage, reverse energy, reverse phase, instantaneous, time limit, inverse time limit, differential—how to select relays.
LIGHTNING PROTECTION DEVICES[1,677] to 1,714
Essential parts: air gaps, resistances, inductances, arc suppressing devices—requirements—air gap arresters—multi-gap arresters; difference between spark and arc; distribution of stress; sparking at the gaps; how the arc is extinguished; effect of frequency; graded shunt resistances; the cumulative or breaking back effect—arresters for grounded Y and non-grounded neutral systems—multiplex connection—horn gap arresters: operation; objection to the horn gap—electrolytic arresters: critical voltage, temporary and permanent; determination of number of cell; putting cell in commission; nature of the film; horn gaps on electrolytic arresters; charging of electrolytic arresters; charging arresters for non-grounded circuits—grounded and non-grounded neutral circuits—ground connections—choke coils: principal objects; principal electrical conditions to be avoided; why choke coils are made in the form of an hour glass; cooling—static interrupters; how to connect condenser and choke coil; effect of condenser.
REGULATING DEVICES[1,715] to 1,762
Regulation of alternators—a.c. feeder regulation—application of induction type regulators; types: induction, and variable ratio transformer regulators; operation of induction regulators; neutral position; regulator capacity—polyphase induction regulators: construction, operation; automatic control; why two relays are used; difficulties encountered in operation of relays; vibration or chattering of the contacts; poor contact of primary relay—variable ratio transformer voltage regulators: types: drum, and dial; dial type for high voltage—small feeder voltage regulators: construction and operation; adjustment—automatic voltage regulators for alternators: method of regulation—line drop compensators: essential parts; connections; construction and operation; diagram of automatic voltage regulator using a line drop compensator—starting compensators: necessity for; construction and operation—star delta switches.
SYNCHRONOUS CONDENSERS[1,763] to 1,776
Characteristics—effect of fully loaded and lightly loaded induction motors on the power factor—synchronous motor used as condenser—effects of low lagging power factors; example—cost of synchronous condenser vs. cost of copper—location of condenser—synchronous condenser calculations and diagram for same.
INDICATING DEVICES[1,777] to 1,838
Virtual value of an alternating current or pressure—the word effectiveerroneously used for virtual: steam engine analogy illustrating this error—classification of instruments: electromagnetic or moving wire, hot wire, induction, dynamometer—electromagnetic or moving iron instruments: types: plunger, inclined coil, magnetic vane; character of scale; objections and precautions—inclined coil instruments—magnetic vane instruments—hot wire instruments—induction instruments: types: shielded pole, rotary field; operation of both types—dynamometers: construction and operation; how arranged to measure watts—watthour meters: types: commutator, induction, Faraday disc; essential parts; object of the motor; object of generator; objection to commutator meter—principles of induction watthour meters: essential parts; strength of rotating field; moving element; retarding element; registering element; frame and bearings; friction compensator; power factor adjustment; frequency adjustment—Faraday disc, or mercury motor ampere hour meter: construction and operation—frequency indicators: types: synchronous motor, resonance, induction; synchronous motor as frequency indicator—resonance frequency indicators: adaptation—induction frequency meter: construction and operation—synchronism indicators: types: lamp or voltmeter, resonance or vibrating reed, rotating field—power factor indicators: wattmeter type; disc, or rotating field type—ground detectors.

CHAPTER LV
ALTERNATING CURRENT SYSTEMS

The facility with which alternating current can be transformed from one voltage to another, thus permitting high pressure transmission of electric energy to long distances through small wires, and low pressure distribution for the operation of lighting systems and motors, gives a far greater variety of systems of transmission and distribution than is possible with direct current.

Furthermore, when the fact that two phase current can be readily transformed into three phase current, and these converted into direct current, and vice versa, by means of rotary converters and rectifiers, is added to the advantages derived by the use of high tension systems, it is apparent that the opportunity for elaboration becomes almost unlimited. These conditions have naturally tended toward the development of a great variety of systems, employing more or less complicated circuits and apparatus, and although alternating current practice is still much less definite than direct current work, certain polyphase systems are now being generally accepted as representing the highest standards of power generation, transmission and distribution.

A classification of the various alternating current systems, to be comprehensive, should be made according to several points of view, as follows:

1. With respect to the arrangement of the circuit, as

2. With respect to transformation, as