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 excitation source.
What is the advantage of separately excited DC motor?
Separately excited DC motor can operate above the base speed in the field-weakening region by reducing the field current independently. Also its speed direction can be reversed by reversing the armature voltage.
What are the advantages and disadvantages of DC generator?
Like other machines, DC generators have some disadvantages, such as: DC generators can’t be applied to a transformer. DC generators have low efficiency because there are copper losses, eddy current losses, hysteresis losses, and mechanical losses. A voltage drop over long distances would occur.
What is the advantages of separately excited generator over self-excited generator and vice versa?
The separately excited dc generators have a decided advantage over the self-excited generators it operates in a stable condition with any field excitation. Thus a wide range of output voltage may be obtained.
What is the advantage of self-excited generator?
Advantages: It is good for variable speed control. The field can be connected to a constant voltage source to ensure full torque is available at all speeds. The armature can be connected to a variable voltage DC source to achieve speed control.
What is DC separately excited generator?
A separately excited DC generator is the one whose field winding is supplied by an independent external DC source (like a battery). The magnitude of generated voltage depends upon the speed of rotation of armature and the field current, i.e., greater the speed and the field current, higher is the generated voltage.
What are the advantages and disadvantages of DC motor?
DC Motor Advantages & Disadvantages
| Advantages | Disadvantages |
|---|---|
| Inexpensive controls for speed regulation | Cogging at speeds of less than 300 rpm |
| Generally a low-cost motor option | Significant power loss on full wave rectified voltage |
| Easily pairs with gear reducers | High starting torque can damage reducers |
What are the advantages and disadvantages of generator?
AC is very easy and efficient to transmit over a long distance rather than DC. The design of the AC generator is fairly simpler than DC generator type. No need for matching a voltage. Cost of ownership is lower.
What is the advantage of DC generator to other power sources?
Efficiency. A DC generator is energy and cost efficient as long as you use it correctly. It is also a very efficient way to power electrical appliances that are made to run on a DC current.
What is the main disadvantage of Series generators?
The main disadvantage of series generators, Output voltage varies as the load varies The e. mf induced in the armature winding is constant with . time Inter pole winding is connected in series with main poles of d.c machine Series motor maintains a more constant speed under varying load.
What is the difference between separately excited DC generator and self excited DC type generator discuss?
In a separately excited (S.E.) machine, the field winding is connected to a separate voltage source while, in a self excited generator field winding is connected across the armature terminals (provides its exciting current) .Hence, the field winding has a large number of turns with a thin conductor.
What is the difference between self excited and separately excited generators?
Self-excited generator: In a self-excited generator the field winding is excited by an external DC source like a battery etc. Separately excited generator: In a separately excited generator the field poles have some residual magnetism. When the armature is rotated a small emf is induced in it.
What are the advantages of DC series motor?
Advantages of DC series motors:
- It is an easy assembly and simple design.
- Vast starting torque.
- Protection is very easy.
- It is cost-effective.
- Series wound motors can use for AC or DC supply so it is also known as universal motors.
- Compare with shunt motor DC series motor develop power for the same construction size.
What is the reason why a separately excited DC generator is no longer used today?
Because it requires a separate DC power supply, the separately excited machine is usually used only when a wide range of voltage control (generator) or speed control (motor) is required.
How can you control the speed of a separately excited dc motor?
The speed of separately excited dc motor can be control by changing the armature voltage and changing field flux. Due to this the speed can be controlled for below rated speed and speed above the rated speed, respectively.
What is the main reason for the voltage drop in a separately excited DC generator as the load is increased?
(3.3) (i). As the load current increases, the terminal voltage falls due to two reasons: (a) The armature reaction weakens the main flux so that actual e.m.f. generated E on load is less than that generated (E0) on no load. (b) There is voltage drop across armature resistance (= ILRa = IaRa).
What is the practical difference between a separately excited and a shunt dc motor?
A separately excited dc motor is a motor whose field circuit is supplied from a separate constant-voltage power supply, while a shunt dc motor is a motor whose field circuit gets its power directly across the armature terminals of the motor.
What is DC shunt generator?
A shunt generator is a type of direct current electric generator in which field winding and armature winding are connected in parallel, and in which the armature supplies both the load current and the field current.
What are the applications of DC generator?
Applications of DC Generators
- These generators are used to charge batteries, provide lighting and provide excitation to alternators.
- They are used to provide field excitation current for regenerative braking in DC locomotives.
- They are used in DC motors where speed control is necessary.
What is DC motor disadvantages?
Disadvantages Of DC Motor
DC motors have a high initial cost. Maintenance cost is high and increased operation due to the presence of brushes and commutator. Due to sparking at brush DC motors cannot operate in explosive and hazardous conditions.
What is the advantage and disadvantage DC shunt motor?
The installation of DC machines is expensive compare with other types of machines. Shunt motor is a constant speed motor, it would be disadvantages where it’s necessary to operate under variable speed. For the same current input, its starting torque is not a high as that of a DC series motor.
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