Basic Circuit Elements
Here we will discuss about all basic clrcuit elements which are used in network analysis such as resistor, capacitor etc. Circuit elements are :- Resistor Capacitor Inductor Energy sources 1. Resistor :-
Measurement of Low value Resistance
For measuring purpose Resistance is categorized into three categories – Low value Resistance ( <1 ohm ) Medium value Resistance (1 to 100 K Ohm) High value Resistance ( >100 K Ohm) 1. Measurement of Low Resistance :- Low Resistance can be measured by various methods – Ammeter-Voltmeter method Kelvin’s double bridge method Potentiometer method… Read More Measurement of Low value Resistance
classification of Dc Generator
Generators are classified according to the method of excitation. Seperately excited dc generators Self excited dc generators Seperately excited dc generator :- In seperately excited dc generator, field current is provided by using an independent external d.c. source. V = Eg – Ia Ra Seperately excited Generators are rarely used in practice.
Armature Reaction in DC machines
There are two windings in a dc generator and a dc motor: Field winding Armature winding. The purpose of field winding is to produce magnetic field (called main flux) whereas the purpose of armature winding is to carry to armature current. Although the armature winding is not provided for the purpose of producing a magnetic field, still the current… Read More Armature Reaction in DC machines
Moving Iron type Instruments
M.I instruments are mainly used for the measurement of alternating currents and voltages, though it can also be used for d.c measurements. Working principle of M.I. Instruments Let a plate or vane of soft iron or of high permeability steel forms the moving element of the system. The iron… Read More Moving Iron type Instruments
Reasons for failure of self exication of DC generator
Failure of self-exication means in Armature winding there will be generation of flux So Dc Generator will not produce any output voltage, while Rotor is rotating. There are so many reasons for failure of self-exication of Dc Generator.These are following… Absence of Resuidal Magnetism Wrong field winding connection Wrong direction of Rotation Resistance of Field-winding (Rf)… Read More Reasons for failure of self exication of DC generator