Tag: electrical machines
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Common Causes of Failures of Power Transformers
As with most of electrical equipment, the key causes of failure of power transformers are either due to electrical failure or mechanical failure. These failures don’t occur that often as compared with other failures in other electrical equipment like switchgear… Read more
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Phase Locked Loop High Precision Motor Speed Control System
AC generators can be utilized in high precision control systems. The AC generator rotor is rotated by the rotating shaft (i.e. the shaft from the motor being controlled). The output AC frequency is proportional to shaft speed. Zero crossings per … Read more
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How to Wire an Industrial Control Motor
Option 1: With a Toggle Switch Let’s consider a simple three-phase, 480V AC motor control circuit consisting of a contactor, overload block, control power transformer, power fuses or (you may use circuit breakers) and the associated components as illustrated … Read more
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How to Perform a Brake Test on a DC Motor
Testing is usually performed on DC machines to establish efficiency and power losses. A brake test is a direct technique that involves applying a brake to a water-cooled pulley mounted on the motor shaft as demonstrated in Figure 1.0. This … Read more
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Features and Applications of Instrument Transformers
Instrument transformers are used in the measurement of voltage, current, energy, and power in ac circuits. The main reasons why instrument transformers are employed in measurements are: To extend (multiply) the range of the measuring instrument. To isolate the measuring … Read more
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What is the difference between a Power transformer and a Distribution Transformer?
Introduction The transformer, in simple terms can be defined as the voltage regulator. It helps in stepping up and stepping down of the voltages. We all have seen transformers in our locality, where the current is passed from higher voltage … Read more
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Speed Control of a DC Compound Motor
A compound motor is a combination of a series and a shunt-wound motor. Compound-wound motor (long shunt) Compound-wound motor (short shunt) The Speed-torque characteristics for a compound motor Compound motor characteristics Speed Control of a DC Compound Motor Speed is … Read more
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DC Shunt Motor Speed Control
In the shunt motor, the motor winding is in parallel with the armature. Shunt-wound motor From the figure above, the supply current I = Ia + If . Unlike a series motor, if the load is removed … Read more
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Speed Control of a DC Series Motor
The dc series motor has its windings and armature connected in series across the supply. DC series motor From the figure above, the armature current Ia also supplies the field, hence when Ia is large on starting for … Read more
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The Essential Components of An Electric Drive
Power electronics deals with the applications of solid-state electronics for the control and conversion of electric power. The conversion techniques require switching power semiconductor devices ON and OFF. The block diagram below shows the essential components of an electric drive … Read more