Electronics Fundamentals, Ch. 8 Introduction to Alternating Current and Voltage Part II AC Circuits

squirrel cage

An aluminum frame within the rotor of an induction motor that forms the electrical conductors for a rotating current.

waveform

The pattern of variations of a voltage or current showing how the quantity changes with time.

phase

The relative angular displacement of a time-varying waveform in terms of its occurrence with respect to a reference.

fundamental frequency

The repetition rate of a waveform.

radian

A unit of angular measurement. There are 2π radians in one complete 360° revolution. One radian equals 57.3°.

duty cycle

A characteristic of a pulse waveform that indicates the percentage of time that a pulse is present during a cycle; the ratio of pulse width to period expressed as either a fraction or as a percentage.

frequency (ƒ)

A measure of the rate of change of a periodic function; the number of cycles completed in 1 s. The unit of frequency is the hertz.

oscilloscope

A measurement instrument that displays signal waveforms on a screen.

ramp

A type of waveform characterized by a linear increase or decrease in voltage or current.

pulse

A type of waveform that consists of two equal and opposite steps in voltage or current separated by a time interval.

sine wave

A type of waveform that follows a cyclic sinusoidal pattern defined by the formula v = A sin θ.

synchronous motor

An ac motor in which the rotor moves at the same rate as teh rotating magnetic field of the stator.

induction motor

An ac motor tha tachieves excitation to the rotor by transformer action.

oscillator

An electronic circuit that produces a time-varying signal without an external input signal using positive feedback.

function generator

An instrument tha tproduces more than one type of waveform.

periodic

Characterized by a reptition at fixed-time intervals.

cycle

One repetition of a periodic waveform.

fall time

THe time inteval required for a pulse to change form 90% to 10% of its amplitude.

slip

The difference between the synchronous speed of the stator field and the rotor speed in an induction motor.

harmonics

The frequencies contained in a composite waveform, which are integer multiples of the pulse repetition frequency (fundamental).

amplitude

The maximum value of a voltage or current.

pulse width

The time interval between the opposite steps of an ideal pulse. For a nonideal pulse, the time between the 50% points on the leading and trailing edges.

period (T)

The time interval of one complete cycle of a periodic waveform.

rise time

The time interval required for a pulse to change form 10% to 90% of its amplitude.

degree

The unit of angular measure corresponding to 1/360 of a complete revolution.

hertz (Hz)

The unit of frequency. One hertz equals one cycle per second.

rms value

The value of a sinusoidal voltage that indicates its heating effect, also known as the effective value. It is equal to 0.707 times the peak value. rms stands for root mean square.

peak-to-peak value

The voltage or current value of a waeform at its maximum positive or negative points.

instantaneous value

The voltage or current value of a waveform at a given instant in time.

peak value

The voltage or current value of a waveform at its maximum positive or negative points.