Characteristics of dc shunt generator
What are the characteristics of a DC shunt motor?
1.17, four important characteristics of a dc shunt motor, namely, torque, speed, armature current, and efficiency, each plotted against the useful output power, are shown. These curves are also known as performance curves of a motor.
What is external characteristic of DC shunt generator?
AC curve is showing the external characteristic of the shunt wound DC generators. It is showing the variation of terminal voltage with the load current. Ohmic drop due to armature resistance gives lesser terminal voltage the generated voltage.
What are various characteristics of DC generator?
Generally, following three characteristics of DC generators are taken into considerations: (i) Open Circuit Characteristic (O.C.C.), (ii) Internal or Total Characteristic and (iii) External Characteristic. These characteristics of DC generators are explained below.
What is the application of DC shunt generator?
Applications of Shunt Wound DC Generators
They are used for general lighting. They are used to charge battery because they can be made to give constant output voltage. They are used for giving the excitation to the alternators. They are also used for small power supply (such as a portable generator).
What is the principle of DC shunt generator?
The DC shunt generator working principle is similar to a normal generator like electromagnetic induction. In this generator, the connection of field winding can be shunt toward the armature. Once input is provided through the prime mover, then the conductor can be turned within the permanent magnetic field.
What are internal and external characteristics of DC series generator?
The external characteristic curve lies below the internal characteristic curve because the value of terminal voltage is less than the generated voltage. Here in the figure OD curve is showing the external characteristic of the series wound DC generator.
Where are DC shunt motors used?
Shunt DC motors can be used in centrifugal pumps, lifts, weaving and lathe machines, blowers, fans, conveyors, spinning machines, and more.
What is critical speed in DC shunt generator?
What is Critical Speed of DC Shunt Generator ? Critical speed is defined as the speed at which the given shunt field resistance is equal to the critical resistance. It is the speed at which the shunt generator just fails to build up its voltage without any external resistance in the field circuit.
What are the applications of a DC shunt motor?
DC Shunt Motor Applications
The applications of shunt DC motor include the following. These motors are used wherever stable speed is required. This kind of DC motor can be used in Centrifugal Pumps, Lifts, Weaving Machine, Lathe Machines, Blowers, Fans, Conveyors, Spinning machines, etc.
Why external characteristics of a DC shunt generator is more drooping than that of a separately excited generator?
The DC shunt generator has drooping characteristics because the terminal voltage decreases as the load current increases.
What is magnetization characteristics of DC shunt generator?
The open circuit characteristics (O.C.C) or magnetization characteristics is the curve that shows the relationship between the generated EMF at no-load (E0) and the field current (If) at constant speed. It is also known as no-load saturation curve.
What is the no-load characteristic of DC generator?
No-load Characteristics :
Under the no-load condition, the generator is said to be open-circuited and rotating at a constant speed. From the EMF equation of dc generator, generated voltage E is directly proportional to flux φ. As φ is directly proportional to field current Ish, an increase in Ish also increases E.
What are the characteristics of a cumulatively compounded DC motor?
Characteristics of Compound DC Motors
The shunt field winding of cumulative motors and their additional flux from series winding produces a large amount of flux which causes a large amount of torque at low speed. It means that motors such as cumulative run at a reasonable speed on light or even no-load conditions.
What is magnetization characteristic?
A typical Magnetization Characteristics is shown in Fig. 7.20. It is known as open-circuit characteristic (OCC) because of the method by which it is determined. It exhibits all the important characteristics of the magnetization curve of iron, modified by the presence of an air-gap in the magnetic circuit.
What is critical field resistance of DC shunt generator?
Critical field resistance is a term that is associated with a shunt DC generator. In a DC shunt generator, the voltage induced across the armature, Va, is directly proportional to the flux acting across it, The flux in a DC generator is directly proportional to the field current, If.
What is the critical speed of a generator?
Critical speed is defined as the speed at which the given shunt field resistance is equal to the critical resistance. It is the speed at which the shunt generator just fails to build up its voltage without any external resistance in the field circuit.
What is BH loop and hysteresis loss?
The magnetising force (H = NI/l) produced by the coil can be changed by varying the current through the coil. It can be seen that when the iron bar is subjected to one complete cycle of magnetisation, the resultant B-H curve traces a loop abcdefa called as hysteresis loop.
What is Lenz force?
Lenz’s law, in electromagnetism, statement that an induced electric current flows in a direction such that the current opposes the change that induced it. This law was deduced in 1834 by the Russian physicist Heinrich Friedrich Emil Lenz (1804–65).
What are hysteresis losses?
Energy Loss due to Hysteresis
During the cycle of magnetization and demagnetization of magnetic substances, energy is spent and this is spent energy appears in the form of heat. This heat loss is known as hysteresis loss. The loss of energy per unit volume of the substance is equal to the area of the hysteresis curve.
What causes hysteresis?
Hysteresis loss is caused by the magnetization and demagnetization of the core as current flows in the forward and reverse directions. As the magnetizing force (current) increases, the magnetic flux increases.
What is the unit of reluctance?
Reluctance(S) is the property of a magnetic circuit opposing the passage of magnetic flux lines, equal to the ratio of the magnetomotive force to the magnetic flux. It is measured in AT/weber. The unit of reluctance is ampere-turns per weber i.e., (Henry)–1.
What is eddy current loss?
If an eddy current of magnitude I flows through a core path of resistance r, it will dissipate energy in the form of heat according to the power equation power = I2R. Since this represents energy being expended for no useful purpose, it is considered as an eddy current loss, sometimes called iron loss.
What is eddy current formula?
Next, the eddy current flowing in each ring is obtained by solving a complex matrix equation of the form [X] [I] = [V] where X is the impedance matrix, I is the eddy current matrix, and V is the induced voltage matrix. ABSTRACT .