Chapter I: Front Matter

THE THOUGHT IS IN THE QUESTION THE INFORMATION IS IN THE ANSWER

HAWKINS
ELECTRICAL GUIDE
NUMBER
SEVEN

QUESTIONS
ANSWERS
&
ILLUSTRATIONS]

A PROGRESSIVE COURSE OF STUDY
FOR ENGINEERS, ELECTRICIANS, STUDENTS
AND THOSE DESIRING TO ACQUIRE A
WORKING KNOWLEDGE OF

ELECTRICITY AND ITS APPLICATIONS

A PRACTICAL TREATISE
by
HAWKINS AND STAFF

COPYRIGHTED, 1915,
BY
THEO. AUDEL & CO.,
NEW YORK.

Printed in the United States.

TABLE OF CONTENTS

GUIDE NO. 7.

~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 ~effective~ _erroneously_ 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~.