Understanding Electric Machines, Transformers, and Motors

Electric Machines: An Overview

Electric machines: any device capable of generating, transforming, or using electric power (generators, alternators, transformers, motors)

Transformers

Transformers: These static machines modify the characteristics of electric current (I and V). They consist of a ferromagnetic core sheet and two windings. The first winding transports high voltage current, and the second circuit is for use. They function through electromagnetic induction, generating an electromotive force (AC).

Motors

Motors: Rotating electrical machines that transform electric energy into mechanical energy. According to the current type, they are:

• DC (Direct Current): Separately excited, series, shunt, compound
• AC (Alternating Current): Speed-synchronous and asynchronous (NUMBER OF PHASE - single and three phase)

DC Motors

Works with the electromotive force (EMF) induction:

• Inductor: Creates the magnetic field and is located in the stator. It has a series of coils where current flows.
• Induced: Creates a magnetic field that opposes the previous one. It has coils in the rotor.
• Collector: Connects the armature coils to the external electronics.
• Brushes: Thin graphite pieces connected to the collector, connecting the collector to the external circuit.

MCC of Independent Excitement

It has two windings connected to two independent voltage sources.

MCC of Series Excitement

The inductor and the armature are in series, fed by the same voltage and the same intensity. The problem is if the load is disconnected, it speeds up. It is used when a high starting torque is needed.

MCC of Derivation Excitement

Inductor and induced are connected in parallel. They are in the same line but with different intensities. The speed is stable and constant. It is used in machines with low torque.

MCC Composed of Excitement

This form has one inductor in series and another in parallel with the induced. It is a combination of the previous ones. It is used when the speed varies much, but a high starting torque is not necessary.

AC Electric Motors

AC electric motors: They are made of a stator (formed by slotted isolated magnetic plates, which introduces the winding) and a rotor (moving part formed by isolated magnetic sheet). Between them is the air gap. The operation is based on generating a magnetic field.