## Basics of Three-Phase Electricity

Updated on 02-Jul-2021 08:45:42
The phase-electricity is produced by a 3-phase generator that has three separate but identical windings, which are called phases. The 3-phase windings of the 3-phase generator are displaced 120° apart from each other and rotate in a common uniform magnetic field. Therefore, a three-phase generator produces three voltages of the same magnitude and frequency but 120° electrical apart from one another.Consider a three-phase alternator as shown in the figure. It has three identical windings or coils R, Y and B displaced 120° electrical from each other and rotating in anticlockwise direction with an angular velocity ω in a magnetic field ... Read More

## Ammeter: Definition & Working Principle

Updated on 02-Jul-2021 08:41:35
An ammeter is a measuring instrument which is used for the measurement of electric current in an electric circuit.An ammeter has a low resistance. The ammeter is connected in series with the load to measure the electric current flowing through it. As, the ammeter has a very low resistance, therefore when it is connected in series with any circuit, it does not change the current.Working PrincipleWhen the ammeter is connected in series with the load, the same current flows through the ammeter that flows through the load, this is because the current in a series circuit remains same through all ... Read More

## Alternative Ways of Generating Electricity

Updated on 02-Jul-2021 08:33:34
Apart from the conventional methods of generating electricity (like thermal, hydroelectric, gas turbine, nuclear power etc.), there are also some alternative methods of generating electricity, which are as follows −Solar PowerThe electricity can be generated from the heat of the sun. In the solar power system, the energy of sunlight is converted into electricity, either directly by the photovoltaic cell or indirectly by using concentrated solar power or combination of both.In solar power generation, the sunlight strikes onto the PV cells, which converts the energy of sunlight into direct current, that can either be stored into batteries or converted into ... Read More

Updated on 02-Jul-2021 08:27:57
Electrical power is generated, transmitted and distributed in the form of 3-phase power because it has the following advantages over the single phase system −The three phase power has a constant magnitude while the power in single phase system is the function of supply frequency i.e. pulsates from zero to maximum value at twice the supply frequency. It can be seen from the following equations, 1 − phase power, $$p=\frac{V_{m}I_{m}}{2}-\frac{V_{m}I_{m}}{2}\cos2\omega\:t$$3 − phase power, $$p=\sqrt{3}(V_{L}I_{L}\cos\varphi)$$In the 3-phase system, a rotating magnetic field can be created in stationary windings, whereas this cannot be done in a single phase system.For the same rating, ... Read More

## Absolute and Relative Magnetic Permeability (µ)

Updated on 02-Jul-2021 08:24:44
Absolute Magnetic PermeabilityThe absolute (or actual) magnetic permeability of a material is its conductivity for the magnetic flux. It is denoted by a Greek letter μ ‘(mu)’ and measured in Henry per meters (H/m). Thus, Absolute permeability of material, $$\mu=\mu_{0}\mu_{r}\:H/m$$Where, μ0 = absolute permeability of air or vacuum.μr = relative permeability of the material.The higher the permeability of a magnetic material, the greater its conductivity for magnetic flux and vice-versa.Air or vacuum is the poorest conductor of the magnetic flux. The absolute magnetic permeability of the air is μ0 = 4π × 10−7 H/m . The absolute permeability (μ) of a ... Read More

## What is a Satellite Link Budget and What Factors Influences It?

Updated on 23-Jun-2021 15:13:15
What is Link Budget Design?A wireless link budget is drafted prior to data transmission to anticipate the possible losses that could occur during transmission of data through the channel. A link budget takes into account all forms of possible losses including path loss, atmospheric absorption loss and channel noise. Link budget is very commonly used in satellite communications.E/S – Earth Station; U/L – Uplink; D/L – Downlink; BER – Bit Error Rate; C/N – Carrier to Noise Ratio; G/T- Ratio of receiver antenna gain and receiver system noise temperatureWhat is a Satellite Link Budget?Satellites deliver vital information global weather, global ... Read More

## Wireless Link Budgets: Design Factors Analysis

Updated on 23-Jun-2021 15:10:31
Some of the factors that decide the performance of a wireless link include transmission power, transmission bandwidth, and antenna gain and signal to noise also increases and hence the SNR decreases. ratio. Let us discuss the performance of a wireless link in view of short range and long range communications separately. The ultimate aim is that our transmitted signal should combat the channel noise and successfully reach the receiver without fading out.Design Factors – Transmission Power and Channel NoiseTransmission PowerIn general, the power of the transmitted signal must be above a certain threshold to ensure that the signal doesn’t get ... Read More

## What are Transmission Bandwidth and System Temperature?

Updated on 23-Jun-2021 15:09:53
In this article, two more important performance parameters of a wireless link are discussed – transmission bandwidth and system temperature.Definition of Transmission BandwidthHigh data rates can be achieved with high bandwidths. It is also known that the transmission bandwidth of the signal is limited by the allocated channel bandwidth. An increase in data rate is achieved not necessarily by only having a large channel bandwidth.Higher the bandwidth, higher is the data rate.We may also use effective modulation techniques such as M-ary modulation to achieve high data rates. OFDM, for example, proves to be handy under flat fading channel conditions. Since ... Read More

## Design factors influencing Reliable Wireless Communication Link

Updated on 23-Jun-2021 15:09:06
For establishing a reliable wireless communication link, a wireless design engineer must operate at optimum levels of performance deciding parameters such as transmission power, transmission bandwidth, antenna gain and so on. Not all the parameters that affect the performance of a wireless link are under the control of a design engineer.Not all performance related parameters are under the control of the designChannel noises, adjacent channel interference, fading- to name a few, are not under the control of the design engineer. Therefore, the designer must tune or adjust the parameters that could be controlled so as to achieve the maximum utilization ... Read More

## What is Effective Isotropic Radiated Power (EIRP)?

Updated on 23-Jun-2021 15:08:10
A wireless link budget, in general, estimates the possible losses that will be encountered by the signal being transmitted and adjustments are made on the design parameters to combat the effects of such losses. EIRP is commonly used in wireless link budget calculations to specify the power level required for transmission.How would you define Effective Isotropic Radiated Power (EIRP)?As the name suggests, the EIRP takes power transmitted by an isotropic source as the reference. EIRP combines the power of the transmitting antenna and its gain. EIRP is expressed as the product of the power of the transmitting antenna and its ... Read More