What are the characteristic curves are drawn in DC generator characteristics?
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.
What are the characteristics of an over compound DC generator?
The external characteristic for over compounded generator is shown by the curve AB in above figure. If series winding amp-turns are adjusted so that, the terminal voltage remains constant even the load current is increased, then the generator is called to be flat compounded.
What is cumulatively compounded DC generator?
Cumulatively compounded DC generator is the generator in which both series and shunt fields are used, connected so that magnetomotive forces from two fields are additive. If the dot is present at that place where the current is entering into dotted coil ends of series and shunt coils.
What is cumulatively compounded?
A compound wound DC motor is said to be cumulatively compounded when the shunt field flux produced by the shunt winding assists or enhances the effect of main field flux, produced by the series winding.
Which of the following characteristics of a DC generator is called Regulation curve?
Eg can be determined by subtracting the drop due to demagnetizing effect of armature reaction from no-load voltage (E0). So that internal characteristic curve lies below the O.C.C. curve. This type of characteristic is also called an armature characteristic or regulation curve.
What is load characteristics of DC shunt generator?
Load characteristic essentially describes how the terminal voltage of the armature of a generator changes for varying armature current Ia. First at rated speed, rated voltage is generated across the armature terminals with no load resistance connected across it (i.e., with S opened) by adjusting the field current.
What is the difference between cumulatively compound and differentially compound wound generator?
2 Compound field windings: GENERATOR FIELD POLE. When the series winding is connected to aid the shunt winding, the generator is called a cumulative compound-wound generator; if the series winding is connected to oppose the magnetic field, it’s called a differential compound-wound generator.
What are the general characteristics of shunt generator?
A shunt generator is a type of dc generator in which the field winding is connected in parallel with the armature winding so that the terminal voltage of the generator is applied across it. The shunt field winding has many turns of fine wire having high resistance.
What are the characteristics of a cumulatively compounded DC motor?
All the characteristics of the compound motor are the combination of the shunt and series characteristic. Cumulative compound motor is capable of developing large amount of torque at low speeds just like series motor. However it is not having a disadvantages of series motor even at light or no load.
Why do we use cumulatively DC motor instead of differentially compounded DC motor?
Cumulative Compounding Cumulative motors give high starting torque like a series motor and reasonable good speed regulation at high speeds like a shunt DC motor. It can work with huge loads and run smoothly after that. This type is practically suitable for most common applications and it is indeed widely used.
Which of the following curves depict the terminal voltage vs load current characteristics of a DC shunt generator?
An external characteristic curve shows the relation between terminal voltage (V) and the load current (IL).
What are the internal characteristics of a compound DC generator?
The internal characteristics of a dc compound generator can be made flat for the range of field currents. When the generator is differentially compounded, with the increase in load current, the voltage across the armature decreases more rapidly than a dc series generator.
Which is better DC series or Differential compound generator?
When the generator is differentially compounded, with the increase in load current, the voltage across the armature decreases more rapidly than a dc series generator. Besides a cumulatively compound generator shows more upward internal characteristic than a standard series generator.
What do you call an over compound DC generator?
If the terminal voltage increases with the increasing load current, we call the machine as over compounded dc generator. Again, if the terminal voltage of the machine decreases with the increasing load current, we call this as under compounded dc generator.
Which is true of a flat compound generator?
The increase in generated voltage is greater than the IaRa drop so that instead of decreasing, the terminal voltage increases as shown by curve A. If series winding turns are so adjusted that with the increase in load current, the terminal voltage substantially remains constant, it is called flat-compounded generator.