What is the Emf equation of DC Generator?
The voltage generated in the armature of any DC generator or motor is determined by an equation. This equation is called the Emf Equation of DC Generator. Today in this article we will study the voltage generated in the armature of a DC machine.
When the armature of a DC machine rotates between the poles of the stator, it cuts the magnetic flux generated by the pole and an EMF is generated in the armature Conductor. When a DC machine acts as a generator, the EMF thus produced is called Generated EMF or Armature EMF.
In contrast, when the DC machine acts as a motor, the EMF thus produced is called Back EMF. Now we will derive the equation for EMF generated in the DC machine.
Suppose in a DC machine
- P = total number of pol
- Φ = magnetic flux generated by each pole
- Z = number of total drivers in the armature
- N = Speed of armature in RPM = n = N / 60 (RPS = Revolution Per Second)
- A = number of total Parallel paths between brushes
- Z / A = number of drivers of total armature connected in series between each Parallel Path
Since the magnetic flux produced by each pole is Φ, then PΦ is the total magnetic flux that will be cut by each armature conductor in one revolution. Hence the average EMF (E) generated in the armature is given as
Since the armature makes n revolution in one second, then one Revolution will be done in 1/n second. Hence the EMF generated in a conductor of the coil of the armature in one round
The EMF equation given above is the average EMF generated in one Conductor of the armature coil. If all the conductors of the armature coil are connected in series, then the total generated EMF
E = (Average EMF generated in one conductor) X (Total conductors connected in series)
The values of Z, A, and P are always fixed in the EMF Equation of the DC Generator so if the Constant parameter is removed by another constant(Say k), the EMF Equation will be something like this
Where
The EMF Equation given above shows that the magnitude of the EMF generated in the armature of a DC motor or generator is dependent on the speed (n) and the magnetic flux (Φ) of the armature. The higher the speed of the armature, the more voltage will be generated.
