Power Control 407
formance of various electrical power control equipment. These standards
provide information concerning the voltage, frequency, power, and cur-
rent ratings for various equipment.ANSI and IEEE Standards
Two well-known organizations publish standards that are of impor-
tance to industry. These organizations are the American National Stan-
dards Institute (ANSI) and the Institute of Electrical and Electronic Engi-
neers (IEEE). The standards published by these organizations are for the
use of the manufacturing industries, as well as power consumers, and in
some cases the general public. These standards are subject to review pe-
riodically; therefore, industrial users should keep up to date by obtaining
the revisions.
These standards were developed from input from manufacturers,
consumers, government agencies, and scientific, technical, and profes-
sional organizations. Often these published standards are used by indus-
try as well as governmental agencies. It should be noted that the National
Electrical Code, discussed previously, is an American National Standards
Institute standard.Definitions
There are several basic definitions that are used when dealing with
electrical power control. These definitions are particularly important when
interpreting control diagrams and standards. A listing of several of the im-
portant power control definitions follows. You should study these defini-
tions.Across-the-line-Control—A method of motor starting in which a motor is
connected directly across the power lines when it is started.
Automatic Starter—A self-acting starter that is completely controlled by
control switches, or some other sensing mechanism.
Auxiliary Contact—A contact that is part of a switching system. It is used in
addition to the main contacts, and is operated by the main contacts.
Braking—A control method that is used to rapidly stop and hold a motor.
Circuit Breaker—An automatic device that opens under abnormally high
current conditions, and can be manually or automatically reset.
Contact—A ent-conducting part of a control device. It is used to open curr
or close a circuit.
Contactor—A control device that is used to repeatedly open or close an