A current transformer (CT) is nothing but a coil wound on a toroidal core. When a large current carried by a conductor is to be measured, it is advisable to avoid the direct connection of ammeter in this high current circuit. For this purpose a current transformer is used. Fig. 1 : Connection of Current […]
The three phase autotransformer is a combination of three single phase autotransformers. It has three windings, one per phase. Fig. 1 : 3 Phase Autotransformer.
What is 3 Phase Autotransformer? Working Principle, Connection Diagram & Applications Read More »
Swinburne’s test is the simplest indirect method to determine the efficiency of D.C machine. In this test the no- load losses are measured separately and from their knowledge, efficiency at any desired load can be predetermined in advance. Figure 1: Arrangement of Swinburne’s test.
What is Swinburne’s Test of DC Motor? Theory & Diagram Read More »
Retardation Test is used for finding the efficiency of shunt wound DC machines. In this test, the rotational losses or stray losses are measured and from their knowledge efficiency at any desired load can be determined. Figure 1: Arrangement of Retardation Test.
What is Retardation Test (or Running Down Test) of DC Motor? Theory & Circuit Diagram Read More »
Figure 1: Arrangement of Brake Test. Brake test is a direct testing method used to find the efficiency of a DC motor. The arrangement for performing brake test on a DC motor is shown in figure (1).
What is Brake Test of DC Machine? Theory, Circuit Diagram & Advantages Read More »
Earth Tester generally used for measurement of earth resistance. Figure 1: Earth Tester.
What is Earth Tester? Working Principle, Construction, Diagram & Measurement Procedure Read More »
The different methods of speed control of DC shunt motor are, Armature control method Field control method Ward-Leonard method. Armature Control Method
Speed Control for DC Shunt Motor – Methods & Diagram Read More »
A four point starter is a protective device used in shunt and compound DC motors to limit the high starting current in the absence of back e.m.f. The construction of four point starter is similar to three point starter except the connection of NVC (No-volt coil).
What is a 4 Point Starter? Working Principle, Construction & Diagram Read More »
Speed-Torque Characteristics of DC Shunt Motor The speed-torque characteristics of DC shunt motor are also known as mechanical characteristics. They can be obtained from torque-current and speed-current characteristics of DC shunt motor.
Speed Torque Characteristics of DC Motor (Shunt & Series) Read More »
Torque Production in DC Motor Consider a DC motor with stator and rotor. When the stator coils are energized, a stator magnetic flux is set up and follows the path as shown in figure (a) with no current in the rotor conductor.
DC Motor Torque Equation – Theory, Diagram & Derivation Read More »