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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Static Kramer Drive

Definition: The static Kramer-drive is the method of controlling the speed of an induction motor by injecting the opposite-phase voltage in the rotor circuit. The injected voltage increases the resistance of the rotor, thus controlled the speed of the motor. By changing the injected voltage, the resistance and speed of an induction motor are controlled.…

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Static Scherbius Drive

The Static Scherbius Drive provides the speed control of a wound rotor motor below synchronous speed. The portion of rotor AC power is converted into DC by a diode bridge. The controlled rectifier works as an inverter and converts the DC power back into AC and feeds it back to the AC source. This drive…

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VSI Fed Induction Motor Drives

Definition: The voltage source inverter is defined as the inverter which takes a variable frequency from a DC supply. The input voltage of the voltage source inverter remains constant, and their output voltage is independent of the load.The magnitude of the load current depends on the nature of the load impedance. The figure below shows…

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