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Showing posts with the label Electrical Engineering

### Microcontroller Uses

Microcontroller Uses The microcontroller is used in multiple industries and applications, together with within the home and enterprise, building automation, producing, robotics, automotive, lighting, sensible energy, industrial automation, communications, and web of things deployments. The best microcontroller facilitates the operation of. mechanical device systems found in everyday convenience things, like ovens, refrigerators, toasters, mobile devices, key fobs, video games, televisions, and lawn-watering systems. They are also common in office machines such as photocopiers, scanners, fax machines, and printers, as well as smart meters, ATMs, and security systems. A more sophisticated microcontroller performs critical functions in aircraft, spacecraft, ocean-going vessels, vehicles, medical and life-support systems, and robots. In medical situations, the microcontroller will regulate the operations of a man-made heart, excretory organ, or another organ. They can

### Proportional Counter

Proportional Counter Construction It is a cylindrical metallic tube filled with a mixture of argon and methane gas in the ratio of 9: l at one atmospheric pressure or less. A thin metallic wire is fixed along the axis of the tube and insulated from it as shown in Fig. i (a). The wire acts as an anode is maintained at a high positive potential with respect to the tube which acts as a cathode. The wire is connected to the pulse amplifier and counting circuit through the resistance R. The cylindrical tube is provided with a thin mica window so that ionizing particles or radiations can enter inside it. Proportional Counter Operation The field produced around the central wire is given by the relation E = V/r ln(b/a) where V = applied a potential difference b = radius of the cylinder a = radius of an axial wire r = distance from the center Wire When a charged particle or radiations such as on, B-particle, or y-photon enters in an ionization chamber, ionization of gas takes place resulting

### Helium Neon Gas Laser

Helium-Neon Gas Laser He-Ne Gas laser  consists of a narrow discharge tube of bore glass or quartz of length 10 to 100 cm with a diameter of the order of 5mm to 10mm. He-Ne Laser construction The tube is Filled With a mixture of helium and neon gases, approximately in the ratio, 85 % a helium and 15% neon, contained at low pressure (typically ~2-3 torr). At each end of the tube, there are electrical connections, referred to as electrodes. The energy or pump supply of the laser is provided by a discharge of around a thousand V through an anode and cathode at every finish of the glass tube. The positive high voltage is connected to the anode and cathode, lS took at ground potential. The anode consists of a metal pin inserted through the glass so that one end extends into the gas region of the tube and the other is connected to the power supply as‘ shown‘ in fig. (b). The laser tube is enclosed between a plane, high-reflecting mirror at one end, and a concave output coupler mi

### Q-switching

Q-switching Q-switching is a technique to produce an extremely short duration high-energy laser pulses of the order of gigawatts, which is often called giant pulse formation. Power is defined as : Power: Energy/ Time (1 Watt= l Joule/ Second) For example, Peak power in a ruby laser operating without Q-switch creates a pulse that lasts 0.5-mile sec, and its energy is 5 Joule. The same laser operating with the Q-switch creates a pulse that lasts 10 nano sec, and have the energy of l Joule. ’ Short pulses from gas lasers. and solid-state lasers, are usually created by using switching inside the laser cavity to change the quality (Q) factor of the laser cavity. Such switching is called Q-switch . In a laser without  Q-switch , the atoms are excited to the lasing level at a particular rate. Lasing starts as soon as ‘population inversion’ is created. In a laser with Q-switch , the feedback which helps in establishing the population inversion is blocked, thus as long as the switch is ‘on’

### Power Line Carrier System

Power Line Carrier System A power line carrier system is used for the protection of transmission lines. The carrier currents with high-frequency range are transmitted and received with the help of transmission lines for protection. The schematic representation of the power line carrier current protection is shown in Fig. (1). Equipment like transmitter, receiver, line tuning unit, master oscillator, power amplifier, etc. are provided at each end of the transmission line in this carrier's current scheme. Various blocks in the schematic representation of power line carrier current protection are explained below: Coupling capacitor The various carrier equipment described 'above is connected to the transmission line with the help of the coupling capacitor. The capacitive reactance is given by l/WC. Hence carrier frequency, offers less reactance while high reactance for normal power frequency.  It can be seen that the carrier current signals are allowed to pass through this capacito

### Earth Pressures

Earth Pressures Earth pressures can be grouped into 3 categories, depending upon the movement of the retaining wall with respect to the soil retained. The soil retained IS also known as the backfill. At-rest Pressure The lateral earth pressure is called at-rest pressure when the soil mass is not subjected to any lateral yielding or movement. This case occurs when the retaining wall is firmly fixed at its top and is not allowed to rotate or move laterally. The figure (a) shows the basement retaining walls .which are restrained against the movement by the basement slab provided at their tops. Another example of at-rest pressure is that of a bridge abutment wall which is restrained at its top by the bridge slab. The at-rest condition is also known as the elastic equilibrium, as no part of soil mass has failed and attained the plastic equilibrium. Active Pressure A state of active pressure occurs when the soil mass yields in such a way that it tends to stretch horizontally. It is a state o

### [ZCS] Zero Current Switching Limitations

Zero Current Switching Limitations Switching losses at tum-OFF can be eliminated and those at turnON can be reduced in a ZCS converter. During resonance, converter operation is insensitive to the diode's junction capacitance as a relatively large capacitor is connected across the output diode. Energy stored in the capacitance of the device will dissipate when power MOSFETs are switched ON by zero current methods. This capacitive tum-ON loss is proportional to the switching frequency. A considerable rate of change of voltage can be ‘ coupled to the gate drive through Miller Capacitor, thereby increasing the switching losses as well as noise during the tum-ON condition. Moreover, ZCS switches are under high current stress so the conduction loss shoots up high. However, ZCS is particularly effective in reducing switching loss for power devices (such as IGBT) with the large tail current in the tum-OFF process.

### Resonant DC Power Supplies

Resonant DC Power Supplies Today We are Discuss About Resonant DC Power Supplies.  If the variation of the dc output voltage isn't wide, resonant pulse inverters will be used. The inverter frequency, which could be the same as ' ‘ the resonant frequency, is very high and the inverter output voltage is almost sinusoidal. Due to the resonant oscillations, the transformer core is always reset and there are no dc saturation problems. The half bridge and full bridge configurations of the resonant inverter are shown 1n fig. (a) and (b) respectively. The size of the transformer and output filter are reduced due to high inverter frequency. Resonant DC Power Supplies Circuit Read More HELIUM NEON GAS LASER Q-SWITCHING

### Comparison between VSI and CSI

Comparison between VSI and CSI In power electronic systems, inverters are an essential component that converts direct current (DC) into alternating current (AC). There are two main types of inverters used in power electronic systems: Voltage Source Inverters (VSI) and Current Source Inverters (CSI). Both have their own unique advantages and disadvantages, and the choice of which to use depends on the specific application and the desired outcome. Comparisons between voltage source inverters and current source inverters are as follows. In voltage source inverters, the input voltage is maintained constant and the amplitude of the output voltage does not depend on the load. However, the waveform of load current, as well as its magnitude, depends upon the nature of load impedance.  In current source inverters (CSI), the input current is constant but adjustable. The amplitude of output current from CSI is freelance of the load. However, the magnitude of output voltage and its undulation outp

### Line-Commutated converter

Line-Commutated converter Today We are Discuss About Line-Commutated converter. In converter input is AC supply, the current will flow through the zero mossing lines while going from a positive peak to negative peak. Thus, a reverse voltage can seem across the device at the same time, which can shut down the thyristor at once. This process is called natural commutation or line commutation as the thyristor is turned off naturally without using any external components or circuit or supply for commutation purpose There are two aspects of line commutation. First, line commutation is possible only in converters that are connected to an AC voltage bus, because the presence of an alternating voltage is necessary to serve as the commutating voltage. Second, to with success succeed put off switch by means that of line commutation, it's essential that the associated line voltage, that is the commutating voltage, should have the polarity which will verse-bias the outgoing thyristor.

Voltage Source Inverters Advantages And Disadvantages Voltage Source Inverters Advantages (i) It has simple logic and can be operated open loop (no feedback of amperes or volts 18 required for steady-state operation). (ii) A single controller can be used with more than one motor. (iii) Reliability 1s good, somewhat better than for PWM types. (iv) Voltage stresses on motor insulation are relatively low. (v) Can be designed for up to 500 Hz operation. Voltage Source Inverters Disadvantage (i) Speed range is limited because of motor cogging at 6 Hz and below. (ii) D.C. link stability can be a problem at low speeds because of motor interaction with d.c. link filter elements. (iii) Requires an additional set of power devices in the input stage if regeneration back to 3.6. the line is desired. (iv) To obtain extended ride-through capability on incoming power loss, a d.c. chopper must be added to the d.c. link. (v) Input power factor 1s poor below the base speed.

### Digital Overcurrent Relay

Digital Overcurrent Relay The overcurrent relay is the most commonly used for a type of protection relay protection of distribution systems. Digital relays are extensively used in the power industry operation. They operate when the circuit current exceeds the predetermined value. The microprocessor uses a multiplexer for sensing the fault currents in a number of circuits and sub-circuits. The microprocessor accepts signals in the voltage farms, the CT fault current derived is first converted into proportionate voltage signals, 'and then fed to the rectifier, multiplexer, analog to digital converter, and the microprocessor. Block diagram of Digital Overcurrent Relay The output of the rectified voltage signals is fed into the multiplexer. The microprocessor (microcomputer) then sends a command for switching ON the desired channel of the multiplexer in order to obtain the rectified voltage in the particular circuit. Since the microprocessor needs digital signals, the output of the mu

### High Resistance Interruption

High Resistance Interruption High Resistance Interruption is a topic of switchgear protection. In this method, resistance increases with time so that the current becomes insufficient to maintain the arc. The rate at which the resistance is increased or the current is decreased is not abnormal so as to cause harmful induced voltages in the system. Because of the resistive nature of the arc discharge, most of the energy in the system will be received by the circuit breaker. The main drawback of this interruption is that the energy dissipation is high. Hence it can be used only in low and medium circuit breakers and in d.c. circuit breakers. Arc resistance can be increased by: (a) Lengthening the arc: Arc resistance is directly proportional to the length of the area so as to increase resistance, the separation between the contacts is increased. (b) Cooling the arc: Cooling helps in the deionization of the medium thus increasing arc resistance. (c) Splitting the arc: The resist

### Digital Protection

Digital Protection In a large interconnected power system, having large sizes of alternators and higher capacity transmission lines, the protective relays and circuit breakers should operate as fast as possible to improve the transient stability of the system. The transients consist of a large number of harmonic currents and voltages with the addition of doing. component,  Both Fundamental components of current and voltage are with inherent large time delays required. For protective relaying purpose applications. Earlier, analog filters were used. The digital filters extract the fundamental components from the transient in about half a cycle. The reasons for using digital protection relaying schemes in place of analog protection offer many advantages over analog protection. As minicomputers, microprocessors, and microcontrollers are developing protective relaying schemes have been developed on these devices. These devices offer low burden, filter in operation, low maintenance, and are

### Current Zero Interruption

Current Zero Interruption Current Zero Interruption is toxic to switch Gear protection.  In a system current drops to zero after every half cycle. during which the arc extinguishes for a brief moment. The medium still contains ions and electrons so has small dielectric strength which can be easily broken down by the rising voltage between the contacts known as restriking voltage. If at current  zero the dielectric strength is built up more rapidly than the voltage across the contacts the arc I'll fail to restrike and the current will be interrupted. Dielectric Strength can be increased by: (a) Recombination of ionized particles into neutral molecules. (b) Replacing ionized particles by unionized particles. Deionization can be Achieved by: (a) Lengthening of the gap: Arc resistance is directly proportional to the length of the gap between contacts. So by opening contacts rapidly dielectric strength can be achieved. (b) High pressure: When pressure increases, the density of particles

### Minimum Oil Circuit Breaker

Minimum Oil Circuit Breaker These types of circuit breakers also utilize oil (transformer oil) as an interrupting medium.  Unlike bulk oil circuit breakers, these designs place the interrupting units in insulating chambers at the live potential. This feature of the design of MOCBs reduces the requirement of oil and these breakers are therefore known as minimum oil circuit breakers . These I designs are available in voltages ranging from 1000 V to 765 kV using the multi-break technique. A typical view of 36 kV MOCB indicating the main parts is shown in figure 4.24. This type of breaker is Widely used in transmission and distribution networks. In an oil circuit breaker, they are drawn across the contacts are contained inside the interrupting pot and thus the hydrogen bubble, formed by the vaporized Oil (gas) is also contained inside the chamber. As the contacts continue to move and When the moving contact rod separates itself from the orifice at the bottom of the chamber, an exit similar

### Optical Isolators

Optical Isolators Optical isolators convert the input signal energy to light energy typically with a light-emitting diode (LED). The light energy is then converted back to electrical energy, typically with a photosensitive transistor, and then passed to the output. The working of an optical isolator is based on optical isolation which is shown in figure 3.23. LEDs produce light when a voltage is applied across them. The direction of the plane of polarization rotates is controlled by how the Faraday rotator affects the light beam. The change in the state of the light can be controlled precisely with a magnet. An optical diode is another term given to a device capable of directing get in this way. Noise levels are also reduced.

### Function Generators

Function Generators The function generators are instruments That are capable of producing a wide variety of waveforms and frequencies. Actually, every one of the waveforms they generate is particularly suitable for a different group of applications. The most common output waveforms are sine-waves, triangular-waves, square-waves, and sawtooth waves. Many Function generators are additionally fit for creating two unique waveforms all the while from different output terminals. Some function generators are also capable of phase locking to an external signal source. One function generator might be utilized to stage lock a second function generator and the two yield signs can be dislodged in stage by a movable sum. The function generator can likewise be stage bolted to a precise recurrence standard, and all its yield waveforms will have a similar recurrence, soundness, and exactness as to the standard. Function Generator Circuit In this instrument, the frequency is controlled by varying the m

### Working of Ground Wires

Working of Ground Wires Direct lightning strokes on transmission lines represent the major source of the failed power system. The objective of the good line design. Therefore, should be to reduce the number of interruptions due to lightning. This objective demands a two-point procedure-first, the incidence of direct strokes to the system should be minimum and secondly, the amplitude and steepness of the overvoltage arising out of the few strokes that will hit the lines should be kept to a minimum. On both the counts, ground wires are found to be suitable. The earthing is provided with the following objectives 1. For the safety of equipment and personnel against lightning and voltage surges providing the discharge path for lightning arresters, gaps, and similar devices. Grounded neutral systems are provided by the ground connections. 2. The grounding of power systems is highly important. A substantial and adequate ground that will not burn off or permit a dangerous rise in voltage under

### Protective Angle and Protective Zone of Ground Wires

Protective Angle and Protective Zone of ground Wires The protective angle of a ground wire is defined as the “angle between a vertical plane through a ground wire and a slanting plane connecting the ground wire with the other most conductor. Experience with various line indicates that an angle of (20°) gives satisfactory protection. Some line with shielding angle as high as (45°) is in use. The performance of the lines is rather poor. However, some utilities have adopted (30°) to be the angle of shielding with good results.