three-wire system

(noun)

a modern wiring system with safety precautions; contains live, neutral, and ground wires

Related Terms

Examples of three-wire system in the following topics:

  • Safety Precautions in the Household

    • Modern household and industrial wiring requires the three-wire system, which has several safety features .
    • The three-wire system is connected to an appliance through a three-prong plug .
    • The three-wire system replaced the older two-wire system, which lacks an earth/ground wire .
    • The standard three-prong plug can only be inserted one way to ensure the proper function of the three-wire system.
    • The three-wire system connects the neutral wire to the earth at the voltage source and the user location.

  • Matter Exists in Space and Time

    • The principle topics covered in elementary mechanics are: fundamental abstracts, the Newtonian system, position and velocity, and Newton's second law.
    • The mental, analytical act of "setting apart" is the essential part of system specification (more later).
    • Finally, Newton's Laws of motion address BODY as the system model; much worthwhile has resulted.
    • Position is the location in space of our system, the BODY.
    • Newton's system was the simplest of all perspectives of matter ~ the BODY.

  • Electric Currents and Magnetic Fields

    • For a long straight wire where I is the current, r is the shortest distance to the wire, and the constant 0=4π10−7 T⋅m/A is the permeability of free space.
    • (μ0 is one of the basic constants in nature, related to the speed of light. ) Since the wire is very long, the magnitude of the field depends only on distance from the wire r, not on position along the wire.
    • The curve C in turn bounds both a surface S through which the electric current passes through (again arbitrary but not closed—since no three-dimensional volume is enclosed by S), and encloses the current.
    • The force on a current carrying wire (as in ) is similar to that of a moving charge as expected since a charge carrying wire is a collection of moving charges.
    • (a) Compasses placed near a long straight current-carrying wire indicate that field lines form circular loops centered on the wire.

  • Length

    • For example: it is possible to cut a length of a wire which is shorter than wire thickness.
    • Length is a measure of one dimension, whereas area is a measure of two dimensions (length squared) and volume is a measure of three dimensions (length cubed).
    • In most systems of measurement, the unit of length is a fundamental unit, from which other units are defined.
    • Units of length may be based on lengths of human body parts, the distance traveled in a number of paces, the distance between landmarks or places on the Earth, or arbitrarily on the length of some fixed object.In the International System of Units (SI), the basic unit of length is the meter and is now defined in terms of the speed of light.
    • In U.S. customary units, English or Imperial system of units, commonly used units of length are the inch, the foot, the yard, and the mile.

  • Combination Circuits

    • This is commonly encountered, especially when wire resistances is considered.
    • In that case, wire resistance is in series with other resistances that are in parallel.
    • In the figure, the total resistance can be calculated by relating the three resistors to each other as in series or in parallel.
    • Essentially, wire resistance is a series with the resistor.
    • If a large current is drawn, the IR drop in the wires can also be significant.

  • Introduction to Simple Harmonic Motion

    • This property, whereby we can analyze a complicated system (in this case the total electric field $\mathbf{E}(q_1 + q_2 + \cdots q_n)$) by breaking it into its constituent pieces (in this case $\mathbf{E}(q_i)$) and then adding up the results is known as linearity.
    • There are three reasons why linear systems are so important.
    • Suppose $x_0$ is an equilibrium point of the system, so $F(x_0) = 0$.
    • The restoring force is the component of the gravitational force acting perpendicular to the wire supporting the mass.This is $-mgsin(\theta)$ .Assuming the wire support is rigid, the acceleration of the mass is in the $\theta$ direction, so $ma=m\ell\ddot\theta$ and we have from Newton's second law: $\ddot{\theta} + \frac{g}{\ell} \sin(\theta) = 0$ .This is a nonlinear equation except for small $\theta$ , in which case $\theta$ .

  • Null Measurements

    • There is a steady drop in potential (IR drop) along the wire, so a variable potential is obtained through contact along the wire.
    • The current I through the long wire is identical.
    • Because a long uniform wire is used for R, the ratio of resistances Rx/Rs is the same as the ratio of the lengths of wire that zero the galvanometer for each EMF.
    • The three quantities on the right-hand side of the equation are now known or measured, and emfx can be calculated.
    • The unknown EMF is thus proportional to the resistance of the wire segment.

  • Photocopy Machines and Printers

    • In the first step of xerography, a high-voltage device (either a corona wire or charge roller) charges a cylindrical drum.
    • This occurs by corona discharge, with output limited by a control grid or screen: a negative charge on the wire ionizes the space between the wire and conductor, so electrons are repelled and pushed onto the conductor.
    • Describe functions of a photocopier and distinguish the three steps of xerography

  • A Microscopic View: Drift Speed

    • Telephone conversations carried by currents in wires cover large distances without noticeable delays.
    • Thus, when a free charge is forced into a wire, the incoming charge pushes other charges ahead of it, which in turn push on charges farther down the line.
    • The resulting electrical shock wave moves through the system at nearly the speed of light.
    • It is possible to obtain an expression for the relationship between the current and drift velocity by considering the number of free charges in a segment of wire.
    • Rearranging terms gives: I = qnAvd, where I is the current through a wire of cross-sectional area A made of a material with a free charge density n.

  • Sound Systems, Computer Memory, Seismograph, GFCI

    • In a sound system, sound can be transmitted from a microphone to a speaker (shown in ).
    • The speaker is then driven by modulated electrical currents (produced by an amplifier) that pass through and magnetize (by inductance) a speaker coil of copper wire, creating a magnetic field.