Induced emf

After performing all the calculations taking into account the notations given in figure 2b, the induced emf becomes... 

Secondary induced emf referred to the primary side (1/2 being secondary induced eml not shown) l i - Excitation or no-load current... 

Note The phasor diagram is drawn taking the applied voltage I/, as the reference phasor. It can also be drawn taking the primary induced emf V as the reference. The logic to the diagram and the subsequent results shall however, remain the same. 

N in the figure) and dt secondary coil (designated as N, ). Electric current through the primary coil causes a magnetic flux in the core and at the same time an impedance to the current and therefore an induced emf across the primary. The magnetic flux in the core in turn induces an emf across the secondary coil, causing a current to flow. The relation between the emf induced in the primary coil (note that this is not the source emf) and the emf induced in the secondary coil is given by... 

According to Lister [1981] deposition may be induced by thermoelectric potentials. The passage of heat normal to a surface (heat flux) can induce a "thermoelectric" effect if the liquid stream flowing across the surface contains a sufficient concentration of charged particles. The induced EMF will generate a particle flux according to the equation... 

The rotor currents are limited by the short-circuit impedance of the rotor circuit. This circuit contains resistance and reactance. The inductive reactance is directly proportional to the frequency of the induced emfs in the rotor. As the rotor accelerates two effects take place -... 

The rotor speed cannot reach the same speed as that of the stator field, otherwise there would be no induced emfs and currents in the rotor, and no torque would be developed. Consequently when the rotor speed is near to the synchronous speed the torque begins to decrease rapidly until it matches that of the load and rotational friction and windage losses. When this balance is achieved the speed will remain constant. 

These induced harmonic currents and emfs can be damaging to electronic equipment in particular and troublesome to computer systems. Often the induced emfs and currents contain very spikey components that have large peak values, and these can be difficult to remove or suppress. 

When the emf is indnced in one winding by the current changing in a second winding the process is called indnction by transformer action or transformer induced emf. 

This process is called induction by rotating action or rotationally induced emf. 

Equation (20.23) can be rewritten with the rotationally induced emfs correctly represented by the rotor speed cOr instead of co as in the case of the synchronous machine -... 

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