A wound-rotor motor (Slip Ring Motor) is a type of induction motor where the rotor windings are connected through slip rings to external resistances. Adjusting the resistance allows control of the speed/torque characteristic of the motor. Wound-rotor motors can be started with low inrush current, by inserting high resistance into the rotor circuit; as the […]
COMPARISON OF SQUIRREL CAGE AND SLIP RING MOTOR Read More »
Transformers reduce the voltage of the electricity supplied by the utility to a level suitable for use by the electric equipment. Since all of the electricity used by a company passes through a transformer, even a small efficiency improvement will result in significant electricity savings. High-efficiency transformers are now available that can reduce total electricity
LOSS AND EFFICIENCY AND COSTING OF TRANSFORMER Read More »
1) KNOW THE LOAD CHARACTERISTICS For line-operated motors, loads fall into three general categories: constant torque, torque that changes abruptly, and torque that change gradually over time. Bulk material conveyors, extruders, positive displacement pumps, and compressors without air unloaders run at relatively steady levels of torque. Sizing a motor for these applications is simple once
STEPS TO BETTER MOTOR APPLICATIONS Read More »
MOTOR A motor is an extended version of a transformer. Here we can introduce the analogy between a transformer and a motor that is a motor is like a transformer with a moving secondary. The primary that is not moving is called stator and the secondary that is moving is called rotor. The type of
To perform the economical analysis of transformer, it is necessary to calculate its life cycle cost, sometimes called total cost of ownership, over the life span of transformer or, in other words, the capitalized cost of the transformer. All these terms mean the same – in one formula, costs of purchasing, operating and maintaining the
LIFE CYCLE COST OF TRANSFORMERS Read More »
TRANSFORMER A transformer is an extended version of an inductor. The flux that is created inside the inductor is used here to induce voltages at other coil, which is termed as secondary coil. If the rate of change of flux can induce voltage across the primary coil, from which it is created, then it is
TYPES OF TRANSFORMERS Read More »
An autotransformer is a transformer which has part of its winding common to the primary and secondary circuits. Fig. 1(a) shows the circuit for a double-wound transformer and Fig. 1(b) that for an auto transformer. The latter shows that the secondary is actually part of the primary, the current in the secondary being (I2-I1). Since
The magnetic flux ϕ set up in the core of a transformer when an alternating voltage is applied to its primary winding is also alternating and is sinusoidal. Let ϕm be the maximum value of the flux and f be the frequency of the supply. The time for 1 cycle of the alternating flux is
EMF EQUATION OF A TRANSFORMER Read More »
Some small transformers for low-power applications are constructed with air between the two coils. Such transformers are inefficient because the percentage of the flux from the first coil that links the second coil is small. The voltage induced in the second coil is determined as follows. E=NdΦ/dt108 where N is the number of turns in
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Principle: An electrical generator is a machine which converts mechanical energy into electrical energy. The energy conversion is based on the principle of the production of dynamically induced emf, where a conductor cuts magnetic flux, dynamically induced emf is produced in it according to Faraday’s Laws of electromagnetic Induction. This emf causes a current to