Contents
Which DC generator can be used as a constant current source?
Applications of Series Wound DC Generators We can clearly see this characteristic from the characteristic curve of series wound generator. They give constant current in the dropping portion of the characteristic curve. For this property they can be used as constant current source and employed for various applications.
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.
What are the characteristics of a separately excited DC generator?
The external characteristic of the separately excited DC generator is obtained by subtracting the drops due to ohmic loss (Ia Ra) in the armature from generated voltage (Eg). Terminal voltage(V) = Eg – Ia Ra. This curve gives the relation between the terminal voltage (V) and load current.
Why do we use separately excited DC motors?
Separately excited DC motors are often used as actuators in trains and automotive traction applications. For their constant speed characteristics, shunt DC motors are used in fixed speed applications such as fans. square of armature current), they can be used in applications that require high starting torque.
What is the output of a DC generator?
A direct-current (DC) generator is a rotating machine that supplies an electrical output with unidirectional voltage and current. The basic principles of operation are the same as those for synchronous generators.
What is the reason for DC generator fails to build up voltage?
The failure of the build up process of a dc generator is caused by no residual magnetism, reversed field connection and high resistance of field circuit.
How do you define separately excited generators?
A DC generator whose field winding or coil is energised by a separate or external DC source is called a separately excited DC Generator. The flux produced by the poles depends upon the field current with the unsaturated region of magnetic material of the poles.
What are the three main characteristics of a DC generator?
Characteristics of DC Generators
- Open Circuit Characteristic (O.C.C.) (E0/If)
- Internal or Total Characteristic (E/Ia) An internal characteristic curve shows the relation between the on-load generated emf (Eg) and the armature current (Ia).
- External Characteristic (V/IL)