What is relation between frequency and voltage?
Equation: E = hc/λ where: f = frequency in Hertz (Hz = 1/sec) λ = wavelength in meters (m) c = the speed of light ( m/s) E = energy in electron Volts ( eV). The reasons for choosing a particular voltage and frequency pair, as well as voltage and frequency only happen in source generator system. On a generator, you have a prime mover (say, an engine) at the design frequency, voltage and frequency aren't related in any fashion except for design. You get fluctuation of frequency and voltage as the load changes.
Since the horizontal axis of this graph can mark the passage of time as well as shaft position in degrees, the dimension marked for one cycle is often measured in a unit of time, most often seconds or fractions of a second.
What is relation between frequency and voltage?
When expressed as a measurement, this is often called the period of a wave. The period of a wave in degrees is alwaysbut the amount of time one period occupies depends on the rate voltage oscillates back and forth. A more popular measure for describing the alternating rate of an AC voltage or current wave than period is the rate of that back-and-forth oscillation.
This is called frequency. The modern unit for frequency is the Hertz abbreviated Hzwhich represents the number of wave cycles completed during one second of time. In the United States of America, the standard power-line frequency is 60 Hz, meaning that the AC voltage oscillates at a rate of 60 complete back-and-forth cycles every second.
In Europe, where the power system frequency is 50 Hz, the AC voltage only completes 50 cycles every second. A radio station transmitter broadcasting at a frequency of MHz generates an AC voltage oscillating at a rate of million cycles every second. Many people believe the change from self-explanatory units like CPS to Hertz constitutes a step backward in clarity. Period and frequency are mathematical reciprocals of one another.
That is to say, if a wave has a period of 10 seconds, its frequency will be 0. An instrument called an oscilloscope, Figure belowis used to display a changing voltage over time on a graphical screen. The ECG is a special-purpose oscilloscope expressly designed for medical use.
General-purpose oscilloscopes have the ability to display voltage from virtually any voltage source, plotted as a graph with time as the independent variable.
The relationship between period and frequency is very useful to know when displaying an AC voltage or current waveform on an oscilloscope screen.
By measuring the period of the wave on the horizontal axis of the oscilloscope screen and reciprocating that time value in secondsyou can determine the frequency in Hertz. Time period of sinewave is shown on oscilloscope. Voltage and current are by no means the only physical variables subject to variation over time.Wave Period and Frequency
Much more common to our everyday experience is sound, which is nothing more than the alternating compression and decompression pressure waves of air molecules, interpreted by our ears as a physical sensation. Because alternating current is a wave phenomenon, it shares many of the properties of other wave phenomena, like sound. For this reason, sound especially structured music provides an excellent analogy for relating AC concepts.
In musical terms, frequency is equivalent to pitch. Low-pitch notes such as those produced by a tuba or bassoon consist of air molecule vibrations that are relatively slow low frequency. In practice, higher "pole orders" are commonly used.
The advantage is that lower rotational speeds can be used to generate the same frequency. If the load on a three-phase system is balanced equally among the phases, no current flows through the neutral point. Even in the worst-case unbalanced linear load, the neutral current will not exceed the highest of the phase currents. Harmonics can cause neutral conductor current levels to exceed that of one or all phase conductors. For three-phase at utilization voltages a four-wire system is often used.
When stepping down three-phase, a transformer with a Delta 3-wire primary and a Star 4-wire, center-earthed secondary is often used so there is no need for a neutral on the supply side. For smaller customers just how small varies by country and age of the installation only a single phase and neutral, or two phases and neutral, are taken to the property. For larger installations all three phases and neutral are taken to the main distribution panel.
From the three-phase main panel, both single and three-phase circuits may lead off. Three-wire single-phase systems, with a single center-tapped transformer giving two live conductors, is a common distribution scheme for residential and small commercial buildings in North America. This arrangement is sometimes incorrectly referred to as "two phase". A similar method is used for a different reason on construction sites in the UK.
A third wirecalled the bond or earth wire, is often connected between non-current-carrying metal enclosures and earth ground. This conductor provides protection from electric shock due to accidental contact of circuit conductors with the metal chassis of portable appliances and tools.
Bonding all non-current-carrying metal parts into one complete system ensures there is always a low electrical impedance path to ground sufficient to carry any fault current for as long as it takes for the system to clear the fault. This low impedance path allows the maximum amount of fault current, causing the overcurrent protection device breakers, fuses to trip or burn out as quickly as possible, bringing the electrical system to a safe state.
AC power supply frequencies[ edit ] Further information: A low frequency eases the design of electric motors, particularly for hoisting, crushing and rolling applications, and commutator-type traction motors for applications such as railways.
Frequency to Wavelength Calculator - Wavelength to Frequency Calculator
However, low frequency also causes noticeable flicker in arc lamps and incandescent light bulbs. The use of lower frequencies also provided the advantage of lower impedance losses, which are proportional to frequency.
Effects at high frequencies[ edit ] Play media A Tesla coil producing high-frequency current that is harmless to humans, but lights a fluorescent lamp when brought near it A direct current flows uniformly throughout the cross-section of a uniform wire. An alternating current of any frequency is forced away from the wire's center, toward its outer surface.
This is because the acceleration of an electric charge in an alternating current produces waves of electromagnetic radiation that cancel the propagation of electricity toward the center of materials with high conductivity.
This phenomenon is called skin effect. At very high frequencies the current no longer flows in the wire, but effectively flows on the surface of the wire, within a thickness of a few skin depths.
For example, the skin depth of a copper conductor is approximately 8.
Since the current tends to flow in the periphery of conductors, the effective cross-section of the conductor is reduced. This increases the effective AC resistance of the conductor, since resistance is inversely proportional to the cross-sectional area.
The AC resistance often is many times higher than the DC resistance, causing a much higher energy loss due to ohmic heating also called I2R loss. Techniques for reducing AC resistance[ edit ] For low to medium frequencies, conductors can be divided into stranded wires, each insulated from one another, and the relative positions of individual strands specially arranged within the conductor bundle.
Wire constructed using this technique is called Litz wire. This measure helps to partially mitigate skin effect by forcing more equal current throughout the total cross section of the stranded conductors.
Litz wire is used for making high-Q inductorsreducing losses in flexible conductors carrying very high currents at lower frequencies, and in the windings of devices carrying higher radio frequency current up to hundreds of kilohertzsuch as switch-mode power supplies and radio frequency transformers.