What are the characteristics of 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.
What are the load characteristics 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. That is why the curve lies below the internal characteristic curve.
What is separately excited DC shunt 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 happens in a separately excited DC generator when the load is increased?
what happens in a generator of this sort when the load is increased? When the load supplied by the generator is increased, IL (and therefore IA) increases. As the armature current increases, the lARA drop increases, so the terminal voltage of the generator falls.
What are the characteristics of DC shunt motor?
Characteristics of a DC Shunt Motor:
- Speed-Armature Current Characteristic:
- Torque-Armature Current Characteristic:
- Speed-Torque Characteristic:
- Break in Field Circuit of a DC Motor:
What is load test on DC shunt generator?
A load test on a DC shunt generator is conducted to know the performance. It is done specifically to know the internal and external characteristics. The external characteristics are known by drawing a graph between the terminal voltage and the load current.
What is OCC curve?
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 a no-load characteristics of DC shunt generator?
No-load Characteristics : No-load or open circuit characteristics of a shunt generator are obtained by plotting ammeter reading (field current) i.e. Ish, versus voltmeter reading E (generated voltage). Under the no-load condition, the generator is said to be open-circuited and rotating at a constant speed.
What sets the voltage on a separately excited generator?
The output voltage of a separately-excited generator can be varied by adjusting the speed of the armature rotation or the field current. A change in speed always results in a corresponding change in output voltage. An increase in field current increases the output voltage only if the field poles are not saturated.
Why is it called separately excited DC generator?
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 is the name of the characteristic curve in DC drive?
The graph plotted between the speed (N) and the armature torque (τa) for a DC motor is known as the speed-torque characteristics. It is also known as mechanical characteristics of DC motor.
What are the characteristics of DC generator?
Characteristics of DC Generators
- Open Circuit Characteristics or Magnetisation Curve.
- Internal Characteristics.
- External Characteristics or Load Characteristics.
- Open Circuit Characteristics (O.C.C)
- Internal Characteristics.
- External Characteristics or Load Characteristics.
- Open Circuit Characteristics.
What is no-load voltage of DC shunt generator?
The straight line is also known as the field- resistance line. The shunt generator continues to build up voltage until the point of intersection of the field-resistance line and the magnetic saturation curve. This voltage is known as the no-load voltage.
What is OCC curve of DC shunt generator?
What is OCC characteristics of DC generator?
Open Circuit Characteristic (O.C.C.) (E0/If) Open circuit characteristic is also known as magnetic characteristic or no-load saturation characteristic. This characteristic shows the relation between generated emf at no load (E0) and the field current (If) at a given fixed speed.
What is no load voltage of DC shunt generator?
What is separately excited?
Definition of separately excited : having the field magnets excited by a current from a separate source —used of a machine.
What is the influence of the load of a separately excited dc motor on the speed in the case of constant armature voltage?
in a separately excited DC motor with armature voltage speed control, if the torque is increased and all other perimeters are left alone (i.e. the Armature voltage is not manually changed), the speed of the machine and armature voltage decreases.
What are the load characteristics of 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 are the characteristics of DC series and shunt motor?
Series winding takes care of the heavy load, whereas the shunt winding prevents the motor from running at dangerously high speed when the load is suddenly removed. These motors have generally employed a flywheel, where sudden and temporary loads are applied like in rolling mills.