Scott-T Transformer Connection

Definition: The Scott-T Connection is the method of connecting two single phase transformer to perform the 3-phase to 2-phase conversion and vice-versa. The two transformers are connected electrically but not magnetically.One of the transformers is called the main transformer, and the other is called the auxiliary or teaser transformer. The figure below shows the Scott-T…

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Three-winding Transformer

Definition: Sometimes in high rating transformer, the third winding is constructed in addition to the primary and the secondary windings. The third winding is called the tertiary winding, and because of the three windings, the transformer is called the three-winding transformer. The voltage ratings of all the three windings of the transformer are usually unequal.The…

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Harmonics in Three Phase Transformers

The harmonic is the distortion in the waveform of the voltage and current. It is the integral multiple of some reference waves. The harmonic wave increases the core and copper loss of the transformer and hence reduces their efficiency. It also increases the dielectric stress on the insulation of the transformer. In a three-phase transformer,…

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Transformer Inrush Current

Definition: The transformer inrush current is the maximum instantaneous current drawn by the primary of the transformer when their secondary is open circuit. The inrush current does not create any permanent fault, but it causes an unwanted switching in the circuit breaker of the transformer. During the inrush current, the maximum value attained by the…

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Potential Transformer (PT)

Definition – The potential transformer may be defined as an instrument transformer used for the transformation of voltage from a higher value to the lower value. This transformer step down the voltage to a safe limit value which can be easily measured by the ordinary low voltage instrument like a voltmeter, wattmeter and watt-hour meters,…

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Current Transformer (CT)

Definition: A current transformer is a device that is used for the transformation of current from a higher value into a proportionate current to a lower value. It transforms the high voltage current into the low voltage current due to which the heavy current flows through the transmission lines is safely monitored by the ammeter. The…

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Dynamics of Electrical Drives

When the motor rotates, the load of the system may rotate or may go through a translational motion. In the translational motion, the position of the body changes from point to point in space.The speed of the load may be different from that of the motor. If the load has different parts, their speed may…

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Induction Motor Braking

The braking is the process of reducing the speed of an induction motor. In braking, the motor works as a generator developing a negative torque which opposes the motion of a motor. The braking of an induction motor is mainly classified into three types. They are Regenerative Braking Plugging or reverse voltage braking Dynamic Braking AC…

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Induction Motor Drives

For variable speed applications, the DC motor drives are used in the past. But this motor has several disadvantages like the presence of commutator and brushes due to which frequent maintenance is required. This problem is overcome by the variable speed induction motor drive. The induction motor drive is cheaper, lighter, smaller, more efficient and…

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Brushless DC Motor Drives

Definition: The self-controlled variable frequency drive employing a sinusoidal PMAC (Permanent Magnet Alternating Current) motor is called brushless DC motor drive. The brushless DC motor drive has some advantages like practically they require no maintenance and have a long life. They also have low frequency, low inertia and friction, and low radio frequency interference and…

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