Virginia Hamilton Essay Example for Free

Virginia Hamilton Essay Virginia Esther Hamilton was born on March 12, 1934 in Yellow Springs, Ohio. She was the youngest of 5 children. She lived on a farm with her family ever since her grandfather Levi Perry was brought as a baby through the underground railroad. Virginia proved to be a wonderful learner, especially when it came to writing. She graduated as one of the best students from her high school. She then attended Antioch College, but soon decided to transfer to Ohio State University. Virginia dreamed of becoming an author and decided to major in literature and creative writing. Virginia soon moved to New York in 1958 where she worked as a museum receptionist, cost accountant, and nightclub singer. Even while doing all these activities, she kept on trying to become an author. She began to study at the New School for Social Research. In 1960 met Arnold Adoff, a teacher who loved poetry. They soon married. Since Arnold could now make money for them, Virginia kept her full attention on writing. However, her writing took a break when she gave birth to two children. Virginia and Arnold soon built their dream house back in Yellow Springs where they both focused on literature. Soon, Virginia became one of the most well known authors in the U. S. During her entire lifetime, she had published 41 extremely popular books. The genres of her books differed, but in them there was much feeling and emotion. Some of her stories described the lives  of African Americans. Virginia won many awards for youth literature. February 19th, 2002 was a sad day for America, as Virginia Esther Hamilton’s death had arrived. Breast cancer had done too much damage. However, the Hamilton family’s blood was still Virginia’s granddaughter Anaya Grace Adoff, was born on November 26, 2008 and is still living today. Virginia is still known as one of America’s most honored writers of children’s literature and will always be.

Digital Media in the Past and Present Essay -- Technology Electronics

Digital Media in the Past and Present In today’s world digital media are everywhere, TV, newspapers, advertisements, and magazines. Almost everywhere you look you will find some sort of digital technology. Digital technology has come along way since the beginning of its time in. Although computers were invented long before; digital technology didn’t start to shine its light until the early 80’s. Originally, NASA developed digital imaging for the US space program in the 1960s (History of the digital camera, 2001). NASA needed a reliable way to get photographs back from the probes, which were never to return to the Earth. George Lucas combined with Adobe to help start the digital art movement with the creation of Photoshop. Companies such as Adobe, Microsoft, Hewitt Packard, Kodak and Sony are a few of the top brands in digital design. A brief history into the digital world mainly begins in 1984 when Sony released its first digital video camera. It used analog recording technology and saved data to a 2.5† floppy disk. The quality of these cameras was quite poor. At the same time Kodak came out with their 8mm camera, but had a hard time finding a buying market. Kodak eventually shut down the electronic photography division. Meanwhile Sony found the market, and began the digital boom. In 1985 the â€Å"Targa video card was introduced. It was a 24 bit color display card, that allowed the user to capture video images to the computer.† (www.home.eznet.net/) The first scanner was introduced in 1986, known as the Thunderscan digitizer. It used the Apple ImageWriter printer to capture the image, in black and white dots. And in 1990 Kodak introduced the first digital camera and photo CD. There was also the introduction of imaging software ... ...sroom" with "digital walls and ceiling" would not need a projector, the information and images would appear on the surrounding surfaces.† He also predicts that these types of projectors will to be able to project 3D images. For example if you were learning about the statue of David, at the click of a button the projector could make a replica of the statue and portray it in the middle of the room. Learning experience will become astronomical in a just a few years. Resources will just be unlimited. The world today is becoming completely based on computers. Less then twenty years ago no one would have believed that almost every household in America would contain a personal computer. Now it’s rare not to own one, some houses contain multiple computers. For this reason its no wonder that the world is going digital. Digital technology just improves so many opportunities.

Synchronous Motor

Chapter (11) Synchronous Motors Introduction It may be recalled that a d. c. generator can be run as a d. c. motor. In like manner, an alternator may operate as a motor by connecting its armature winding to a 3-phase supply. It is then called a synchronous motor. As the name implies, a synchronous motor runs at synchronous speed (Ns = 120f/P) i. e. , in synchronism with the revolving field produced by the 3-phase supply. The speed of rotation is, therefore, tied to the frequency of the source.Since the frequency is fixed, the motor speed stays constant irrespective of the load or voltage of 3phase supply. However, synchronous motors are not used so much because they run at constant speed (i. e. , synchronous speed) but because they possess other unique electrical properties. In this chapter, we shall discuss the working and characteristics of synchronous motors. 11. 1 Construction A synchronous motor is a machine that operates at synchronous speed and converts electrical energy into mechanical energy. It is fundamentally an alternator operated as a motor.Like an alternator, a synchronous motor has the following two parts: (i) a stator which houses 3-phase armature winding in the slots of the stator core and receives power from a 3-phase supply [See (Fig. (11. 1)]. (ii) a rotor that has a set of salient poles excited by direct current to form alternate N and S poles. The exciting coils are connected in series to two slip rings and direct current is fed into the winding from an external exciter mounted on the rotor shaft. The stator is wound for the same number of poles as the rotor poles.As in the case of an induction motor, the number of poles determines the synchronous speed of the motor: Fig. (11. 1) 293 Synchronous speed, N s = where 120f P f = frequency of supply in Hz P = number of poles An important drawback of a synchronous motor is that it is not self-starting and auxiliary means have to be used for starting it. 11. 2 Some Facts about Synchronous Motor Some salient features of a synchronous motor are: (i) A synchronous motor runs at synchronous speed or not at all. Its speed is constant (synchronous speed) at all loads. The only way to change its speed is to alter the supply frequency (Ns = 120 f/P). ii) The outstanding characteristic of a synchronous motor is that it can be made to operate over a wide range of power factors (lagging, unity or leading) by adjustment of its field excitation. Therefore, a synchronous motor can be made to carry the mechanical load at constant speed and at the same time improve the power factor of the system. (iii) Synchronous motors are generally of the salient pole type. (iv) A synchronous motor is not self-starting and an auxiliary means has to be used for starting it. We use either induction motor principle or a separate starting motor for this purpose.If the latter method is used, the machine must be run up to synchronous speed and synchronized as an alternator. 11. 3 Operating Principle The fact that a synchronous motor has no starting torque can be easily explained. (i) Consider a 3-phase synchronous motor having two rotor poles NR and SR. Then the stator will also be wound for two poles NS and SS. The motor has direct voltage applied to the rotor winding and a 3-phase voltage applied to the stator winding. The stator winding produces a rotating field which revolves round the stator at synchronous speed Ns(= 120 f/P).The direct (or zero frequency) current sets up a two-pole field which is stationary so long as the rotor is not turning. Thus, we have a situation in which there exists a pair of revolving armature poles (i. e. , NS ? SS) and a pair of stationary rotor poles (i. e. , NR ? SR). (ii) Suppose at any instant, the stator poles are at positions A and B as shown in Fig. (11. 2 (i)). It is clear that poles NS and NR repel each other and so do the poles SS and SR. Therefore, the rotor tends to move in the anticlockwise direction. After a period of half-cycle (or ? = 1 /100 second), the polarities of the stator poles are reversed but the polarities of the rotor poles remain the same as shown in Fig. (11. 2 (ii)). Now SS and NR attract 294 each other and so do NS and SR. Therefore, the rotor tends to move in the clockwise direction. Since the stator poles change their polarities rapidly, they tend to pull the rotor first in one direction and then after a period of half-cycle in the other. Due to high inertia of the rotor, the motor fails to start. Fig. (10. 2) Hence, a synchronous motor has no self-starting torque i. e. , a synchronous motor cannot start by itself.How to get continuous unidirectional torque? If the rotor poles are rotated by some external means at such a speed that they interchange their positions along with the stator poles, then the rotor will experience a continuous unidirectional torque. This can be understood from the following discussion: (i) Suppose the stator field is rotating in the clockwise direction and the rotor is als o rotated clockwise by some external means at such a speed that the rotor poles interchange their positions along with the stator poles. (ii) Suppose at any instant the stator and rotor poles are in the position shown in Fig. 11. 3 (i)). It is clear that torque on the rotor will be clockwise. After a period of half-cycle, the stator poles reverse their polarities and at the same time rotor poles also interchange their positions as shown in Fig. (11. 3 (ii)). The result is that again the torque on the rotor is clockwise. Hence a continuous unidirectional torque acts on the rotor and moves it in the clockwise direction. Under this condition, poles on the rotor always face poles of opposite polarity on the stator and a strong magnetic attraction is set up between them.This mutual attraction locks the rotor and stator together and the rotor is virtually pulled into step with the speed of revolving flux (i. e. , synchronous speed). (iii) If now the external prime mover driving the rotor is removed, the rotor will continue to rotate at synchronous speed in the clockwise direction because the rotor poles are magnetically locked up with the stator poles. It is due to 295 this magnetic interlocking between stator and rotor poles that a synchronous motor runs at the speed of revolving flux i. e. , synchronous speed. Fig. (11. 3) 11. Making Synchronous Motor Self-Starting A synchronous motor cannot start by itself. In order to make the motor self-starting, a squirrel cage winding (also called damper winding) is provided on the rotor. The damper winding consists of copper bars embedded in the pole faces of the salient poles of the rotor as shown in Fig. (11. 4). The bars are short-circuited at the ends to form in effect a partial Fig. (11. 4) squirrel cage winding. The damper winding serves to start the motor. (i) To start with, 3-phase supply is given to the stator winding while the rotor field winding is left unenergized.The rotating stator field induces currents in the damper or squirrel cage winding and the motor starts as an induction motor. (ii) As the motor approaches the synchronous speed, the rotor is excited with direct current. Now the resulting poles on the rotor face poles of opposite polarity on the stator and a strong magnetic attraction is set up between them. The rotor poles lock in with the poles of rotating flux. Consequently, the rotor revolves at the same speed as the stator field i. e. , at synchronous speed. iii) Because the bars of squirrel cage portion of the rotor now rotate at the same speed as the rotating stator field, these bars do not cut any flux and, therefore, have no induced currents in them. Hence squirrel cage portion of the rotor is, in effect, removed from the operation of the motor. 296 It may be emphasized here that due to magnetic interlocking between the stator and rotor poles, a synchronous motor can only run at synchronous speed. At any other speed, this magnetic interlocking (i. e. , rotor poles facing o pposite polarity stator poles) ceases and the average torque becomes zero.Consequently, the motor comes to a halt with a severe disturbance on the line. Note: It is important to excite the rotor with direct current at the right moment. For example, if the d. c. excitation is applied when N-pole of the stator faces Npole of the rotor, the resulting magnetic repulsion will produce a violent mechanical shock. The motor will immediately slow down and the circuit breakers will trip. In practice, starters for synchronous motors arc designed to detect the precise moment when excitation should be applied. 11. 5 Equivalent Circuit Unlike the induction motor, the synchronous motor is connected to two electrical systems; a d. . source at the rotor terminals and an a. c. system at the stator terminals. 1. Under normal conditions of synchronous motor operation, no voltage is induced in the rotor by the stator field because the rotor winding is rotating at the same speed as the stator field. Only the impressed direct current is present in the rotor winding and ohmic resistance of this winding is the only opposition to it as shown in Fig. (11. 5 (i)). 2. In the stator winding, two effects are to be considered, the effect of stator field on the stator winding and the effect of the rotor field cutting the stator conductors at synchronous speed.Fig. (11. 5) (i) The effect of stator field on the stator (or armature) conductors is accounted for by including an inductive reactance in the armature winding. This is called synchronous reactance Xs. A resistance Ra must be considered to be in series with this reactance to account for the copper losses in the stator or armature winding as shown in Fig. (11. 5 (i)). This 297 resistance combines with synchronous reactance and gives the synchronous impedance of the machine. (ii) The second effect is that a voltage is generated in the stator winding by the synchronously-revolving field of the rotor as shown in Fig. 11. 5 (i)). This generat ed e. m. f. EB is known as back e. m. f. and opposes the stator voltage V. The magnitude of Eb depends upon rotor speed and rotor flux ? per pole. Since rotor speed is constant; the value of Eb depends upon the rotor flux per pole i. e. exciting rotor current If. Fig. (11. 5 (i)) shows the schematic diagram for one phase of a star-connected synchronous motor while Fig. (11. 5 (ii)) shows its equivalent circuit. Referring to the equivalent circuit in Fig. (11. 5 (ii)). Net voltage/phase in stator winding is Er = V ? Eb Armature current/phase, I a = where 2 Zs = R 2 + X s a hasor difference Er Zs This equivalent circuit helps considerably in understanding the operation of a synchronous motor. A synchronous motor is said to be normally excited if the field excitation is such that Eb = V. If the field excitation is such that Eb < V, the motor is said to be under-excited. The motor is said to be over-excited if the field excitation is such that Eb > V. As we shall see, for both normal an d under excitation, the motor has lagging power factor. However, for over-excitation, the motor has leading power factor.Note: In a synchronous motor, the value of Xs is 10 to 100 times greater than Ra. Consequently, we can neglect Ra unless we are interested in efficiency or heating effects. 11. 6 Motor on Load In d. c. motors and induction motors, an addition of load causes the motor speed to decrease. The decrease in speed reduces the counter e. m. f. enough so that additional current is drawn from the source to carry the increased load at a reduced speed. This action cannot take place in a synchronous motor because it runs at a constant speed (i. e. , synchronous speed) at all loads.What happens when we apply mechanical load to a synchronous motor? The rotor poles fall slightly behind the stator poles while continuing to run at 298 synchronous speed. The angular displacement between stator and rotor poles (called torque angle ? ) causes the phase of back e. m. f. Eb to change w. r. t. supply voltage V. This increases the net e. m. f. Er in the stator winding. Consequently, stator current Ia ( = Er/Zs) increases to carry the load. Fig. (11. 6) The following points may be noted in synchronous motor operation: (i) A synchronous motor runs at synchronous speed at all loads.It meets the increased load not by a decrease in speed but by the relative shift between stator and rotor poles i. e. , by the adjustment of torque angle ?. (ii) If the load on the motor increases, the torque angle a also increases (i. e. , rotor poles lag behind the stator poles by a greater angle) but the motor continues to run at synchronous speed. The increase in torque angle ? causes a greater phase shift of back e. m. f. Eb w. r. t. supply voltage V. This increases the net voltage Er in the stator winding. Consequently, armature current Ia (= Er/Zs) increases to meet the load demand. iii) If the load on the motor decreases, the torque angle ? also decreases. This causes a smaller phase shift of Eb w. r. t. V. Consequently, the net voltage Er in the stator winding decreases and so does the armature current Ia (= Er/Zs). 11. 7 Pull-Out Torque There is a limit to the mechanical load that can be applied to a synchronous motor. As the load increases, the torque angle ? also increases so that a stage is reached when the rotor is pulled out of synchronism and the motor comes to a standstill. This load torque at which the motor pulls out of synchronism is called pull—out or breakdown torque.Its value varies from 1. 5 to 3. 5 times the full— load torque. When a synchronous motor pulls out of synchronism, there is a major disturbance on the line and the circuit breakers immediately trip. This protects the motor because both squirrel cage and stator winding heat up rapidly when the machine ceases to run at synchronous speed. 299 11. 8 Motor Phasor Diagram Consider an under-excited ^tar-connected synchronous motor (Eb < V) supplied with fixed excitation i. e. , back e. m. f. Eb is constantLet V = supply voltage/phase Eb = back e. m. f. /phase Zs = synchronous impedance/phase (i) Motor on no loadWhen the motor is on no load, the torque angle ? is small as shown in Fig. (11. 7 (i)). Consequently, back e. m. f. Eb lags behind the supply voltage V by a small angle ? as shown in the phasor diagram in Fig. (11. 7 (iii)). The net voltage/phase in the stator winding, is Er. Armature current/phase, Ia = Er/Zs The armature current Ia lags behind Er by ? = tan-1 Xs/Ra. Since Xs >> Ra, Ia lags Er by nearly 90Â °. The phase angle between V and Ia is ? so that motor power factor is cos ?. Input power/phase = V Ia cos ? Fig. (11. 7) Thus at no load, the motor takes a small power VIa cos ? phase from the supply to meet the no-load losses while it continues to run at synchronous speed. (ii) Motor on load When load is applied to the motor, the torque angle a increases as shown in Fig. (11. 8 (i)). This causes Eb (its magnitude is constant as excitation is fixed) to lag behind V by a greater angle as shown in the phasor diagram in Fig. (11. 8 (ii)). The net voltage/phase Er in the stator winding increases. Consequently, the motor draws more armature current Ia (=Er/Zs) to meet the applied load. Again Ia lags Er by about 90Â ° since Xs >> Ra. The power factor of the motor is cos ?. 300 Input power/phase, Pi = V Ia cos ?Mechanical power developed by motor/phase Pm = Eb ? Ia ? cosine of angle between Eb and Ia = Eb Ia cos(? ? ? ) Fig. (11. 8) 11. 9 Effect of Changing Field Excitation at Constant Load In a d. c. motor, the armature current Ia is determined by dividing the difference between V and Eb by the armature resistance Ra. Similarly, in a synchronous motor, the stator current (Ia) is determined by dividing voltage-phasor resultant (Er) between V and Eb by the synchronous impedance Zs. One of the most important features of a synchronous motor is that by changing the field excitation, it can be made to operate from lagging to eadin g power factor. Consider a synchronous motor having a fixed supply voltage and driving a constant mechanical load. Since the mechanical load as well as the speed is constant, the power input to the motor (=3 VIa cos ? ) is also constant. This means that the in-phase component Ia cos ? drawn from the supply will remain constant. If the field excitation is changed, back e. m. f Eb also changes. This results in the change of phase position of Ia w. r. t. V and hence the power factor cos ? of the motor changes. Fig. (11. 9) shows the phasor diagram of the synchronous motor for different values of field excitation.Note that extremities of current phasor Ia lie on the straight line AB. (i) Under excitation The motor is said to be under-excited if the field excitation is such that Eb < V. Under such conditions, the current Ia lags behind V so that motor power factor is lagging as shown in Fig. (11. 9 (i)). This can be easily explained. Since Eb < V, the net voltage Er is decreased and turn s clockwise. As angle ? (= 90Â °) between Er and Ia is constant, therefore, phasor Ia also turns clockwise i. e. , current Ia lags behind the supply voltage. Consequently, the motor has a lagging power factor. 301 ii) Normal excitation The motor is said to be normally excited if the field excitation is such that Eb = V. This is shown in Fig. (11. 9 (ii)). Note that the effect of increasing excitation (i. e. , increasing Eb) is to turn the phasor Er and hence Ia in the anti-clockwise direction i. e. , Ia phasor has come closer to phasor V. Therefore, p. f. increases though still lagging. Since input power (=3 V Ia cos ? ) is unchanged, the stator current Ia must decrease with increase in p. f. Fig. (11. 9) Suppose the field excitation is increased until the current Ia is in phase with the applied voltage V, making the p. . of the synchronous motor unity [See Fig. (11. 9 (iii))]. For a given load, at unity p. f. the resultant Er and, therefore, Ia are minimum. (iii) Over excitation T he motor is said to be overexcited if the field excitation is such that Eb > V. Under-such conditions, current Ia leads V and the motor power factor is leading as shown in Fig. (11. 9 (iv)). Note that Er and hence Ia further turn anti-clockwise from the normal excitation position. Consequently, Ia leads V. From the above discussion, it is concluded that if the synchronous motor is under-excited, it has a lagging power factor.As the excitation is increased, the power factor improves till it becomes unity at normal excitation. Under such conditions, the current drawn from the supply is minimum. If the excitation is further increased (i. e. , over excitation), the motor power factor becomes leading. Note. The armature current (Ia) is minimum at unity p. f and increases as the power factor becomes poor, either leading or lagging. 302 11. 10 Phasor Diagrams With Different Excitations Fig. (11. 10) shows the phasor diagrams for different field excitations at constant load. Fig. (11. 10 (i )) shows the phasor diagram for normal excitation (Eb = V), whereas Fig. 11. 10 (ii)) shows the phasor diagram for under-excitation. In both cases, the motor has lagging power factor. Fig. (11. 10 (iii)) shows the phasor diagram when field excitation is adjusted for unity p. f. operation. Under this condition, the resultant voltage Er and, therefore, the stator current Ia are minimum. When the motor is overexcited, it has leading power factor as shown in Fig. (11. 10 (iv)). The following points may be remembered: (i) For a given load, the power factor is governed by the field excitation; a weak field produces the lagging armature current and a strong field produces a leading armature current. ii) The armature current (Ia) is minimum at unity p. f and increases as the p. f. becomes less either leading or lagging. Fig. (11. 10) 11. 11 Power Relations Consider an under-excited star-connected synchronous motor driving a mechanical load. Fig. (11. 11 (i)) shows the equivalent circuit for one phase, while Fig. (11. 11 (ii)) shows the phasor diagram. Fig. (11. 11) 303 (i) (ii) Input power/phase, Pi = V Ia cos ? Mechanical power developed by the motor/phase, Pm = Eb ? Ia ? cosine of angle between Eb and Ia = Eb Ia cos(? ? ? ) Armature Cu loss/phase = I 2 R a = Pi ? Pm a Output power/phasor, Pout = Pm ?Iron, friction and excitation loss. (iii) (iv) Fig. (11. 12) shows the power flow diagram of the synchronous motor. Fig. (11. 12) 11. 12 Motor Torque Gross torque, Tg = 9. 55 where Pm N-m Ns Pm = Gross motor output in watts = Eb Ia cos(? ? ? ) Ns = Synchronous speed in r. p. m. Shaft torque, Tsh = 9. 55 Pout N-m Ns It may be seen that torque is directly proportional to the mechanical power because rotor speed (i. e. , Ns) is fixed. 11. 13 Mechanical Power Developed By Motor (Armature resistance neglected) Fig. (11. 13) shows the phasor diagram of an under-excited synchronous motor driving a mechanical load.Since armature resistance Ra is assumed zero. tan? = Xs/Ra = ? an d hence ? = 90Â °. Input power/phase = V Ia cos ? Fig. (11. 13) 304 Since Ra is assumed zero, stator Cu loss (I 2 R a ) will be zero. Hence input power a is equal to the mechanical power Pm developed by the motor. Mech. power developed/ phase, Pm = V Ia cos ? Referring to the phasor diagram in Fig. (11. 13), (i) AB = E r cos ? = I a X s cos ? Also AB = E b sin ? ? E b sin ? = I a X s cos ? or I a cos ? = E b sin ? Xs Substituting the value of Ia cos ? in exp. (i) above, Pm = = V Eb Xs VEb Xs per phase for 3-phaseIt is clear from the above relation that mechanical power increases with torque angle (in electrical degrees) and its maximum value is reached when ? = 90Â ° (electrical). Pmax = V Eb Xs per phase Under this condition, the poles of the rotor will be mid-way between N and S poles of the stator. 11. 14 Power Factor of Synchronous Motors In an induction motor, only one winding (i. e. , stator winding) produces the necessary flux in the machine. The stator winding must draw re active power from the supply to set up the flux. Consequently, induction motor must operate at lagging power factor.But in a synchronous motor, there are two possible sources of excitation; alternating current in the stator or direct current in the rotor. The required flux may be produced either by stator or rotor or both. (i) If the rotor exciting current is of such magnitude that it produces all the required flux, then no magnetizing current or reactive power is needed in the stator. As a result, the motor will operate at unity power factor. 305 (ii) If the rotor exciting current is less (i. e. , motor is under-excited), the deficit in flux is made up by the stator. Consequently, the motor draws reactive power to provide for the remaining flux.Hence motor will operate at a lagging power factor. (iii) If the rotor exciting current is greater (i. e. , motor is over-excited), the excess flux must be counterbalanced in the stator. Now the stator, instead of absorbing reactive power, a ctually delivers reactive power to the 3-phase line. The motor then behaves like a source of reactive power, as if it were a capacitor. In other words, the motor operates at a leading power factor. To sum up, a synchronous motor absorbs reactive power when it is underexcited and delivers reactive power to source when it is over-excited. 11. 15 Synchronous CondenserA synchronous motor takes a leading current when over-excited and, therefore, behaves as a capacitor. An over-excited synchronous motor running on no-load in known as synchronous condenser. When such a machine is connected in parallel with induction motors or other devices that operate at low lagging power factor, the leading kVAR supplied by the synchronous condenser partly neutralizes the lagging reactive kVAR of the loads. Consequently, the power factor of the system is improved. Fig. (11. 14) shows the power factor improvement by synchronous condenser method. The 3 ? ? load takes current IL at low lagging power factor cos ?L. The synchronous condenser takes a current Im which leads the voltage by an angle ? m. The resultant current I is the vector sum of Im and IL and lags behind the voltage by an angle ?. It is clear that ? is less than ? L so that cos ? is greater than cos ? L. Thus the power factor is increased from cos ? L to cos ?. Synchronous condensers are generally used at major bulk supply substations for power factor improvement. Advantages (i) By varying the field excitation, the magnitude of current drawn by the motor can be changed by any amount. This helps in achieving stepless control of power factor. ii) The motor windings have high thermal stability to short circuit currents. (iii) The faults can be removed easily. 306 Fig. (11. 14) Disadvantages (i) (ii) (iii) (iv) There are considerable losses in the motor. The maintenance cost is high. It produces noise. Except in sizes above 500 RVA, the cost is greater than that of static capacitors of the same rating. (v) As a synchronous m otor has no self-starting torque, then-fore, an auxiliary equipment has to be provided for this purpose. 11. 16 Applications of Synchronous Motors (i) Synchronous motors are particularly attractive for low speeds (< 300 r. . m. ) because the power factor can always be adjusted to unity and efficiency is high. (ii) Overexcited synchronous motors can be used to improve the power factor of a plant while carrying their rated loads. (iii) They are used to improve the voltage regulation of transmission lines. (iv) High-power electronic converters generating very low frequencies enable us to run synchronous motors at ultra-low speeds. Thus huge motors in the 10 MW range drive crushers, rotary kilns and variable-speed ball mills. 307 11. 17 Comparison of Synchronous and Induction Motors S. Particular No. 1.Speed 2. 3. 4. Power factor Excitation Economy 3-phase Induction Motor Remains constant (i. e. , Ns) from Decreases with load. no-load to full-load. Can be made to operate from Operates a t lagging lagging to leading power factor. power factor. Requires d. c. excitation at the No excitation for the rotor. rotor. Economical fcr speeds below Economical for 300 r. p. m. speeds above 600 r. p. m. Self-starting No self-starting torque. Auxiliary means have to be provided for starting. Complicated Simple More less Synchronous Motor 5. Self-starting 6. 7. Construction Starting torque 308

How Banking Law Affects Finance Management Finance Essay - Free Essay Example

Sample details Pages: 11 Words: 3362 Downloads: 1 Date added: 2017/06/26 Category Finance Essay Type Argumentative essay Did you like this example? The Bank of England (hereafter also BOE, the Bank) was once a regulatory and supervisory body of all banks and financial institutions in the United Kingdom but this has changed since the happenings of Bank of Credit and Commerce International (BCCI) in 1991, it was one of the worlds largest banks at the time; some refer what happened as Britains biggest banking scandal while some describe it as one of the biggest bank fraud in history. Whatever it was remembered as; what we should recognise is that the BCCI scandal has had significant impacts in the world of banking (particularly for the United States and United Kingdom). The bank (at least the UK branches) was forced shut by the Bank of England in the summer of 1991 after having confirmed that it has been involved in numerous fraud activities, of money laundering, and so on. Don’t waste time! Our writers will create an original "How Banking Law Affects Finance Management Finance Essay" essay for you Create order Allegations was made against the BOE, criticising its poor oversight of the banking sector and that it had, again and again, ignored the warnings that could have proved the criminal nature of BCCI. Consequent to what had happened, when the Labour Government came into power in 1997; the BOEs responsibility as a regulator and supervisory body has been transferred to the Financial Services Authority (FSA- by the BOE Act 1998). The recent financial crisis has raised doubts, once again, and this time on the FSA. Doubts were brought on the effectiveness of the FSA in fulfilling its principal role of regulating all financial services and whether are they competent enough in the continuation of role. George Osborne (the Chancellor of Exchequer) seems relatively keen in scrapping the FSA and significantly to transfer responsibility for dealing with the day-to-day supervision of banks and financial services back to the Bank of England- he seems determined to re-empower the BOE of its original role. In his first Mansion House Speech in the summer, he made it clear that the Financial Services Authority will cease to exist in its current form. But should this really be done? After all financial crisis hits the world once every 10 years or so, this is somewhat inevitable and it is only a part of the economic cycle. The answer which we aim to approach by the end of this essay is whether the powers, in fact, should be reverted back to the BOE, while simultaneously; trying to discover whether does the BOE at present hold sufficient powers over banks (and particularly commercial banks since risks usually arise in them) or should the powers it holds be increased or decreased. The two questions are directly linked since when we say that the BOEs power should be increased; the most significant power that should be handed to them was the power that was taken away from them in 1998. On the other hand, when we say that their powers are to be decreased, it could mean no further than that the supervisory powers that were taken away from them should be remained as it is- this is so since any further decease in power will make the BOE a central bank with only carries with it the title as a central bank but in fact does not operate as one. It is essential, in order to discover answer these questions, to first look at the powers which currently vest with the BOE and the FSA. BOE and the FSA What should be understood is that the Bank of England remains of crucial importance in the operations of banks and in banking law even after the transfer of some of its functions to the Financial Services Authority in 1998; it remains the banks bank and more so, despite the transfer, the Bank retains responsibility for the integrity of the financial system as a whole. So what does it do? First, it should be noted that the BOE acts as a banker to the government. What we meant by this is that it hold the accounts of the central government, they hold accounts for the Exchequer (the governmental department that receives and controls national revenue). Moreover, it acts as a banker to other banks (hence why it is the banks bank). We could see this in three aspects: It means that the leading banks (Lloyds TSB, Barclays, Santander, HSBC etc.) keep their accounts with the BOE and therefore, settle their obligations (to pay one and other) at the bank- it occurs by way of an accounting process. The BOE is the lender of last resort- in exceptional circumstances; the BOE will intervene and rescue a bank which is facing financial problems in order to promote the sustainability of the banking system. A good example we saw recently is the problems which was faced by Northern Rock. The BOE has a virtually monopoly in issuing banknote in the United Kingdom (though limited powers is given to certain banks in Scotland and Northern Ireland). Furthermore, as we have suggested, since the Bank of England retains responsibility for the integrity of the financial system as a whole, we see that it is specifically responsible for: a) Stability of the monetary system, b) Financial system infrastructure and particularly the payment system, c) the overview of the financial system as a whole, d) the ability to conduct financial rescue operations, and e) the efficiency and effectiveness of the financial sector. Stability of the monetary system simply means stable prices and this encompasses within it, two elements; low inflation and confidence in the sterling, and this is defined by the government with its inflation targets. The BOE has been given powers (under the BOE Act) for the formulation of monetary policy and this is usually implemented through the setting of interest rates (which they have a monopoly under Part II and Schedule 3). The Banks Monetary Policy Committee meets each month to set the official base rate of interest for the economy. With regards to payment systems, the Banking Act specially enables the BOE to oversee payment systems between financial institutions. As we have iterated again and again, the Financial Services Authority is now the regulatory and supervisory body for all banks and financial institutions in the United Kingdom and this remains so until real changes take place (i.e. Our Chancellors proposal to scrap it), reverting this power back the BOE. The Financial Services and Market Act (FSMA) which came into force on 1st December 2001, provides the functions, responsibilities and powers of the FSA. Further, by result of the Act; the FSA became the official Single Financial Services Regulator for the United Kingdom. The prior distinction between the different financial services regulators; for banks of which is the BOE, for insurance of which is the Department for Trade and Industry for example; were removed and the Financial services Authority became the regulator responsible for all forms of financial services- banking, insurance and investment business are all within the scope of its regulatory power. Whilst enormous powers h ave been conferred on the FSA by the FSMA, it is also provided under that that the FSA must act compatibly (in accordance) within four regulatory objectives- Section 2; 1) to maintain confidence within the financial system, 2) to promote public understanding of the system, 3) to secure the suitable degree of protection for consumers and 4) to reduce financial institutions from making use of a regulated business for financial crime. Additionally, it is specifically provided under Section 2(3) that, when discharging its general functions, the FSA must have regard to seven additional factors; and this includes (amongst others), to make efficient use of its resources and to ensure proportionality between burden and restriction imposed with the benefits. But what responsibility do FSA actually have? The Memorandum of Understanding, provides that under FSMA, the FSA responsible for (amongst others): i) authorisation of activities and prudential supervision of banks and financial instituti on, and ii) supervising the financial system, securities listings, clearing and settlement system. With regards to the 1st responsibility, for banks, the FSMA provides that the FSA must grant authorisation for institutions to carry out the business of banking (accepting deposits as well as issuing loans at an interest)- Section 19 imposed an overall prohibition on anyone carrying out or purporting to carry out a regulated activity (banking activities fall within the ambit of regulated activities) and this is so except where they have been authorised or where they have been exempted from authorisation (Section 19(1)). As we have thus far noted, there is no single body, in truth, in the regulation of the financial system (even though the upper-hand powers seem to lie with the FSA). Also, what should be noted is that the Treasury also plays a part in this (this includes the politicians- hence why politics plays a role in banking and banking regulation); and together (the 3 bodies) has a shared objective of financial stability. They work together towards their objective by whats called the tripartite agreement (in which stipulate it is their shared responsibilities to achieve financial stability- or so it says as we will see) and this was the position until the recent global financial crisis where not even one of the bodies sees it coming. Initially, it was believed that none of the bodies were effective in satisfying their job but after investigation, it was claimed that essentially it was the FSA who was asleep in their job. Argument for and against the reversal of powers back to BOE As we shall see later, the arguments for the programme described to be restoring the previous glory of the BOE are relatively strong, at least so far as demonstrating that changes to the current governance of the financial system are eminent. In Sir Martin Jacobs report: Re-empower the Bank of England, the former Director of the Bank of England seem somewhat supportive of the view of Mr Osborne and described the arrangement of the 3 bodies ÃÆ' ¢Ãƒ ¢Ã¢â‚¬Å¡Ã‚ ¬Ãƒâ€šÃ‚ ¦contributed to the failure of the regulatory systemÃÆ' ¢Ãƒ ¢Ã¢â‚¬Å¡Ã‚ ¬Ãƒâ€šÃ‚ ¦ and which is, in turn, a central cause of the catastrophe which engulfed our economy. What appears relatively clear since the recent global financial crisis is that, it is quite unlikely that anyone would (any longer) back Gordon Browns decision in 1997 on the transfer of BOEs responsibility for prudential supervision of banks and financial institutions to the FSA. It was said that whilst the tripartite agreement appears to give the r esponsibility for financial stability to all of the 3 bodies, the main role (if not the sole) in fact lies with the BOE- as could be seen in the agreement; the BOE has to ensure the stability of the financial system through its monetary policies and maintaining a broad overview of the system. Consequently of this de facto responsibility, the supporters claimed, the fact that the supervision of individual banks and the financial institution has been taken from the BOE meant that they no longer have any direct touch with them making it impossible to know what was going on in the credit markets. The effect of the transfer of powers meant that the BOE have no access to information, and more significantly, they lacks whats necessary to fulfil their responsibility of financial stability- as they no longer have direct touch with banks (whats important in our perspective) and financial institutions, the BOE could not have (sufficient) influence them (and thus in no way could it actually hav e any control). On that front, one may argue that this does not matter since the tripartite agreement depends upon the flow of information between FSA and BOE; and thus as long as there was an effective flow of information, there couldnt have been any issues since BOE can simply alert the FSA if it notices any warnings that could harm the stability of the financial sector. Yet, this is precisely the point, the BOE could only alert if they are direct touch and without that power, it meant it is impossible for them to do so. Also, this counter-argument was flawed on the ground of the recent financial crisis- for example: The FSA has explained that the happenings with Northern Rock were the outcome of the lack of the flow of information between it and the Bank- The Bank of England left in the dark and was thus unaware of the danger. The Proposals put forward by the Chancellor in which will be of major significance to banking law (if it were to be brought) were that the FSA would be broken up, the supervisory and regulatory powers would be taken by a new Prudential Regulation Authority (PRA), it will operate as a subsidiary of the BOE. Moreover, a new committee (the Financial Policy Committee- FPC- another subsidiary) will be introduced and it will be responsible for attaining financial stability (which obviously is a function of the BOE). With regards to the part of the FSA which was supposed to protect consumer and crack on crimes, it will be injected into 2 new agencies. Our main focus, evidently, lies with the creation of PRA and FPC, which as far as the proposal suggests, will become the subsidiaries of the bank. This is obviously an important change and an improvement from pre-1998. Prior to the decision taken by Gordon Brown, the BOE was responsible for the regulation and supervision of banks and financial institutions and this is one of its responsibilities along with many others. The meaning of this change, however, is that although, it is still the BOE which is still responsible but this is delegated to its subsidiary, and they will be accountable to the BOE. In such a way, direct flow of information could be, to a degree, guaranteed and this would avoid the problem that arose with Northern Rock. It has also been strongly asserted (by Melvyn King and Sir Martin Jacob for example) that the one of the flaws with the current system was that the BOE was not fully involved in resolving troubles which bank faces. Without direct touch and therefore no knowledge of the states of banks meant that the BOE cannot provide support when bank needs help. More so, even if there were effective flow of in formation between the FSA and the BOE, the BOE lacks the advantage of having first-hand information which would allow them to act efficiently. Remember, the BOE have many functions and amongst this was that it is the lender of the last resort. How could it possible make effective use this function if they do not have direct touch and the most up-to-date knowledge of the health of the banks? as pointed out by Mervyn King (Governor of the BOE). Furthermore, as we said earlier, how could the Bank achieve its core objective of financial stability if they could not actually supervise and regulate banks and financial institution? The reliance on the working of the three bodies (and in particular; the FSA and the BOE) together towards the objective of financial stability are defective in the sense that we have already mentioned and was proved to be a failure in the recent financial crisis. Scrapping the division of control between the FSA and the BOE, accordingly, should certainly improve the state of our financial system. Whilst we saw that there are a number of arguments in flavour of re-empowering the Bank of England, one thing we can possibly ask is to what extent could this avoid another financial crisis? The structure proposed appears to be a bureaucratic system of control whereby each of the subsidiaries; the FPC, MPC and PRA would be accountable to the BOE and in such a way, it was hoped the BOE to satisfy their two core objectives; monetary stability and financial stability. The problem with such a structure is that again there is a reliance on the flowing of crucial information between the subsidiaries. As with (for example) a company which operates a bureaucratic structure where all departments is under the control of the managing director and therefore are all going after the companys goal, each department still have distinctive roles and communications can sometimes be very difficult. The same applies to the system we have here, although they are all under the same objectives, the fact tha t they have different role can make communication difficult. As proven by past experience, effective communication of information is not easy and subsuming the 3 bodies under the BOE can result in a complex structure and could simply not work. After all regulating and supervising banks so as to avoid them from doing unauthorised activities and avoiding risks from building up (by for example by setting a limit in capital holding and amount in which it could lend etc.) fall within the responsibility of PRA but all these could have an effect that coincides with the responsibility of FPC. Being able to work together and ensuring a sufficient flow of information, thus, is the key to any governance of the financial system. The structure is not necessary if we could guarantee these two elements between the FSA and the BOE. What we must not ignore is the fact that global financial crisis (as we have already said) is only part of the economic cycle and thus it is wrong for radical changes ev ery time it ticks. Rather what should be brought are perhaps improvements, and the fact that the earlier Labour Government brought a new committee to help improve communications between the three bodies, may very well be adequate. Having due regard of the arguments posed for and against the re-empowering of the BOE, it seems relatively evident that the arguments for the proposal stood much stronger than that against. If it is one of the BOEs core objectives to sustain financial stability, it could not do so without the regulating and supervising powers of banks and financial institutions and the current division of control (that of FSA and BOE mainly) creates inefficiency in the financial system. Besides, the fact that the BOE is the lender of the last resort, and yet it is receiving information on the health of the banks (under the current system) after the FSA, will altogether, delay decision makings of the BOE (i.e. whether to give loan to a bank- for example: Lloyds TSB in the recent crisis). This could accordingly result the financial system in getting to the worse side- where remedial actions could no longer effective. Leaving it too late appears, however, inevitable under the current system. Even if it was true that we should not undertake radical changes every single time we suffer from a financial crisis, but the current changes appears essential to ensure the efficiency and effectiveness of the the financial system. Rather, what should be remembered for the next financial crisis (which will be inevitable) is that we are human-beings (which the BOE consist of) and so there is always going to be errors. We should allow for a margin of error and until it passes an unforgiveable level. In fact, nothing should really be changed if the system has been working so well until the financial crisis pop-up. Drawing up all the considerations, it appears that re-empowerment of the BOE is crucial and that the powers that it currently holds are insufficient to fulfil its responsibilities as a central bank (monetary and financial stability). For the reason that majority of the risks usually come from commercial and investment banking meant that the powers it holds, is particularly insufficient since these banks are usually big in size and therefore is unlikely to listen to advices of the Bank unless when they themselves realises the risks. As we have said, if the powers of the Bank is ever to be further reduced, the BOE would become a de june central bank with no actual functions as one. Increasing the current powers (as proposed- to return its regulatory and supervisory powers) will give the bank a de facto regulatory role which would give it satisfactory controls over banks as well as other financial institution. The latter is what is necessary and is what should, in fact, be done.