Tricky but Easy Electrical Engineering!
V-curve and power factor control of generator are closely related to each other. V-curve of Generator is basically a plot of variation of armature current with the change in field current. For a constant power, V-curve can only be obtained for generator connected to infinite bus / grid. There does not exists any such curve for an isolated … Read more
Ferroresonance is a resonance phenomenon caused by the nonlinear inductance and system capacitance. For better understanding of ferroresonance, it is worth to remind the linear resonance in LRC circuit. Linear Resonance Let us consider a linear LRC circuit as shown in figure below. Total Impedance of Network Z = (jωL – j/ωC) where w … Read more
As we know, in any kind of electrical machine there are two types of winding. One is Armature Winding which carries the load current and other is field winding which carries the DC current to create required magnetic flux. This magnetic flux serves the purpose of coupling between mechanical power and electrical power. In DC … Read more
Capability Curve of Generator defines the boundaries within which it can deliver reactive power continuously without overheating. Generator rating is specified in terms of MVA and power factor at a particular terminal voltage. Active power delivered by generator is only limited by the power delivering capability of turbine. But the reactive power which a generator … Read more
End Part Heating is localized heating at the end region of stator core of Generator. This heating is a result of eddy current loss in the laminations of stator core due to end turn flux of armature winding. This heating imposes a limitation on the operation of Synchronous Generator know as End Part Heating Limit. … Read more
VVVF stands for Variable Voltage Variable Frequency. VVVF Speed Control method is widely used method for Induction Motor. Origin of VVVF Speed Control As we know that synchronous speed of machine is given as N (rpm) = 120f/P …………………………………(1) where f is frequency and P is number of pole. Thus if we can change the … Read more
Lets us consider a doubly excited magnetic system as shown in figure below. In this model of machine, both stator as well as rotor is assumed to be salient pole type. Let’s assume that stator is energized from source Vs whereas rotor is energized with source Vr. Total torque developed in such doubly excited magnetic … Read more
The oil can only be filled in the transformer which satisfies the standard specifications mentioned by the manufacturer of transformer. Normally Transformer is supplied with gas filled i.e. the Main Tank of Transformer is filled with Nitrogen gas under some specified pressure to prevent any degradation of the insulation of core and winding. But we … Read more
Variable Frequency Transformer or simply VFT is quite a new technology to connect two asynchronous Grids. Asynchronous Grids mean two power systems operating at two different frequencies. The world’s first VFT was installed and commissioned in the year of 2004 at Hydro- Quebec’s Langlois substation, where it is used to exchange up to 100 MW … Read more
In Permanent Magnet DC Motor or PMDC Motor, permanent magnet is used to create the working flux in the air gap instead of field winding. The construction of rotor is same as that of the Conventional DC Motor i.e. rotor of PMDC Motor consists of armature core, armature winding and commutator. Generally, there are two … Read more