excitation of dc generator
... Separately excited DC generators have many advantages over self-excited DC generators. It can operate in stable condition with any field excitation and gives wide range of output voltage. The main disadvantage of these kinds of generators is that it is very expensive of providing a separate excitati ...
... Separately excited DC generators have many advantages over self-excited DC generators. It can operate in stable condition with any field excitation and gives wide range of output voltage. The main disadvantage of these kinds of generators is that it is very expensive of providing a separate excitati ...
UNIT – 5 Explain the different starting methods for 3
... Note that starting current is as large as five times the full-load current but starting torque is just equal to the full-load torque. Therefore, starting current is very high and the starting torque is comparatively low. If this large starting current flows for a long time, it may overheat the motor ...
... Note that starting current is as large as five times the full-load current but starting torque is just equal to the full-load torque. Therefore, starting current is very high and the starting torque is comparatively low. If this large starting current flows for a long time, it may overheat the motor ...
Motor Control
... In squirrel cage motors, the conductors in the rotor slots are shorted at the ends. Therefore, the resistance of the conductors is fixed and cannot be changed. However, resistors can be connected in-line with the motor to reduce the starting voltage. During the acceleration period at the moment a mo ...
... In squirrel cage motors, the conductors in the rotor slots are shorted at the ends. Therefore, the resistance of the conductors is fixed and cannot be changed. However, resistors can be connected in-line with the motor to reduce the starting voltage. During the acceleration period at the moment a mo ...
SIMULATION OF ELECTRIC MACHINE AND
... torque and initial conditions. However, in most instances, a specified operating condition can only be obtained after running the simulation for a time that will depend on the starting setting of these initial conditions. This situation will occur if, in the above case of the induction motor, torque ...
... torque and initial conditions. However, in most instances, a specified operating condition can only be obtained after running the simulation for a time that will depend on the starting setting of these initial conditions. This situation will occur if, in the above case of the induction motor, torque ...
ee328 sheets - Arab Academy for Science, Technology
... Calculate the power input, line-current & output torque. 2. A 250V series motor has an armature & field resistance of 0.06Ω & 0.025 respectively. The motor draws a line current of 25A when running at 850rpm. Calculate the speed when the line current is 18A, for the same supply voltage. 3. A shunt mo ...
... Calculate the power input, line-current & output torque. 2. A 250V series motor has an armature & field resistance of 0.06Ω & 0.025 respectively. The motor draws a line current of 25A when running at 850rpm. Calculate the speed when the line current is 18A, for the same supply voltage. 3. A shunt mo ...
DIAGNOSTIC NEWS What Can Go Wrong with Turbo Generator Rotor Windings
... Radial displacement of coils in the end winding can cause high compressive loads on slot liners, particularly at slot ends. Combined with axial copper expansion this leads to liner abrasion and ground faults. Service overheating is often a result of relatively small changes in the ventilation circui ...
... Radial displacement of coils in the end winding can cause high compressive loads on slot liners, particularly at slot ends. Combined with axial copper expansion this leads to liner abrasion and ground faults. Service overheating is often a result of relatively small changes in the ventilation circui ...
Unit 31 Direct Current (DC) Motors
... Unit 31 DC Motors Review: 9. When full voltage is applied to the armature and reduced voltage is applied to the shunt field, the motor will operate above base speed. 10. The direction of rotation of a direct current motor can be changed by reversing the connection of either the armature or the field ...
... Unit 31 DC Motors Review: 9. When full voltage is applied to the armature and reduced voltage is applied to the shunt field, the motor will operate above base speed. 10. The direction of rotation of a direct current motor can be changed by reversing the connection of either the armature or the field ...
Electromagnetic Induction©98
... the current, the magnets to determine their polarity, and the coils to determine the direction of the windings. 1. Connect one of the coils in series with the galvanometer and hold the coil still against the magnet. Does electricity flow in the wires? Explain. 2. With the magnet fixed, move the coil ...
... the current, the magnets to determine their polarity, and the coils to determine the direction of the windings. 1. Connect one of the coils in series with the galvanometer and hold the coil still against the magnet. Does electricity flow in the wires? Explain. 2. With the magnet fixed, move the coil ...
High Efficiency Motor Protection Industry White Paper
... HMCPs were initially designed. The National Electric Code (NEC) was changed slightly in 1996 to address this problem. The problem stems from the fact that the NEC allows certain settings for HMCPs (currently 800% of full load current, 1100% for design E motors) based on the motor’s locked rotor curr ...
... HMCPs were initially designed. The National Electric Code (NEC) was changed slightly in 1996 to address this problem. The problem stems from the fact that the NEC allows certain settings for HMCPs (currently 800% of full load current, 1100% for design E motors) based on the motor’s locked rotor curr ...
Commutator (electric)
A commutator is the moving part of a rotary electrical switch in certain types of electric motors and electrical generators that periodically reverses the current direction between the rotor and the external circuit. It consists of a cylinder composed of multiple metal contact segments on the rotating armature of the machine. The commutator is one component of a motor; there are also two or more stationary electrical contacts called ""brushes"" made of a soft conductor like carbon press against the commutator, making sliding contact with successive segments of the commutator as it rotates. The windings (coils of wire) on the armature are connected to the commutator segments. Commutators are used in direct current (DC) machines: dynamos (DC generators) and many DC motors as well as universal motors. In a motor the commutator applies electric current to the windings. By reversing the current direction in the rotating windings each half turn, a steady rotating force (torque) is produced. In a generator the commutator picks off the current generated in the windings, reversing the direction of the current with each half turn, serving as a mechanical rectifier to convert the alternating current from the windings to unidirectional direct current in the external load circuit. The first direct current commutator-type machine, the dynamo, was built by Hippolyte Pixii in 1832, based on a suggestion by André-Marie Ampère. Commutators are relatively inefficient, and also require periodic maintenance such as brush replacement. Therefore, commutated machines are declining in use, being replaced by alternating current (AC) machines, and in recent years by brushless DC motors which use semiconductor switches.