Whenever an electric drive is disconnected from the supply, the speed of the driving motor gradually decreases and becomes zero. Braking is a generic term used to describe a set of operating conditions for electric drive systems. It includes rapid stopping of the electric motor, holding the motor shaft to a specific position, maintaining the
Compare Electrical and Mechanical Braking Read More »
[sc_fs_faq html=”true” headline=”h2″ img=”” question=”Mention speed control methods of DC shunt motors?” img_alt=”” css_class=””] 1. Armature control method, 2. Field control method, 3. Voltage control method [/sc_fs_faq] The speed of a dc motor is given by [latex]N=\frac{V-I_{a} R_{a}}{Z \phi}\left(\frac{A}{P}\right) \text { (or) } \quad N=\frac{K\left(V-I_{a} R_{a}\right)}{\phi} [/latex] where V = applied voltage, Ia = armature current Ra
Speed Control of DC Shunt Motor – Pedagogy Zone Read More »
There are three types of characteristics. Open circuit characteristics (OCC) or magnetisation characteristics (E2 versus If). Internal characteristics or total characteristics (E versus Ia). External characteristics or voltage regulated characteristics (V versus IL) Separately excited DC generator characteristics For a given dc generator it is clear that the induced emf is proportional to the flux
Characteristics of DC Generator – Pedagogy Zone Read More »
DC generators can be classified according to their methods of field excitation. There are two types of DC generators on the basis of excitation. Separately excited DC generators Self excited DC generators Separately excited DC generators If the field winding is excited by a separate DC supply, then the generator is called separately DC generator.
Types of DC Generators – Pedagogy Zone Read More »
DC Generator : An electrical generator is a rotating machine which converts mechanical energy into electrical energy. It is shown in figure. This energy conversion is based on the principle of electromagnetic induction. According to Faraday’s laws of electromagnetic induction, whenever a conductor is moved in a magnetic field, dynamically induced e.m.f is produced in
DC Generator Principle and Parts of DC Generator Read More »
Centrifugal pumps are the devices which convert the mechanical energy into hydraulic energy by means of centrifugal force acting on the fluid. Centrifugal pumps are classified as roto dynamic type of pumps in which a dynamic pressure is developed to lift liquids from lower level to higher level. The basic working principle of centrifugal pump
Centrifugal Pumps – Classification and Components Read More »
In a double acting reciprocating pump, the suction and delivery strokes occur simultaneously. When the crank rotates from IDC to ODC, a vacuum is created on the left side of the piston and the liquid is sucked from the sump through suction valve S1. At the same time, the liquid on the right side of
Working of a Double Acting Reciprocating Pump Read More »
In a single acting reciprocating pumps, liquid acts on one side of the piston only. Image shows a single acting reciprocating pump which has one suction pipe and one delivery pipe. It is usually placed above the liquid level in the sump. When the crank rotates clockwise from dead centre (IDC) (from A) to outer
Working of a Single Acting Reciprocating Pump Read More »
The reciprocating pumps is a positive displacement pump. It operates on the principle of actual displacement or pushing the liquid by a piston or plunger that reciprocates in a closely fitting cylinder. These pumps usually have one or more cylinders which are alternatively filled with liquid to be pumped and then emptied again. In this
Reciprocating Pumps – Classification Read More »
There are two methods of dimensional analysis used. Rayleigh’s method Buckingham π-Theorem Rayleigh’s Method In Rayleigh’s method, the expression is determined for a variable depending upon maximum three or four variables only. If the number of independent variables becomes more than four, it is very difficult to find the expression for the dependent variable. So,
Methods of Dimensional Analysis – Pedagogy Zone Read More »