What is an electrical machine? Types, Working Principles, and Examples
An electrical machine is a device which converts mechanical energy into electrical energy or vice versa. Thus, electrical generators and electrical motors are both electrical machines. Transformers are also electrical machines, which do not convert between mechanical and electrical forms but instead transform AC power from one voltage level to another.
Electrical Generator:
An electrical generator is an electrical machine which converts mechanical energy into electrical energy. The basic working principle of an electrical generator is based on the Faraday's law of electromagnetic induction. It states that whenever a conductor moves in a magnetic field, an emf gets induced within the conductor. This phenomenon is called as generator action.
Key components of a generator:
- Rotor: Rotating part, receives mechanical energy from a prime mover like a turbine or engine. Common prime movers are Steam turbines, water turbines, wind turbines, internal combustion (IC) engines etc.
- Stator: Stationary part, houses the windings where EMF is induced.
Types of Electrical Generators:
- AC Generators: Produce alternating current (AC).
- DC Generators: Produce direct current (DC).
- Separately Excited
- Self Excited: (Series Wound, Shunt Wound, Coumpound wound)
Electrical Motor:
A motor is an electrical machine which converts electrical energy into mechanical energy. When a current carrying conductor is placed in a magnetic field, the conductor experiences a mechanical force and this is the working principle of an electric motor.
Main components of an electrical motor:
- Stator: Produces a magnetic field.
- Rotor: Rotates due to electromagnetic force.
Types of Electric Motors:
- AC Motors:
- DC Motors:
Some motors (like induction motors) require electrical supply only to the stator, while others may require supply to both stator and rotor (one for field exciter and one for armature winding).
Transformers:
A Transformer does not actually make conversion between mechanical and electrical energy, but they transfer electric power from one circuit to another circuit. They can increase or decrease (step-up or step-down) the voltage while transferring the power without changing the frequency, but with the corresponding decrease or increase in the current. Input power and output power of an electrical transformer should ideally be the same.
Step up transformers increases the voltage level from primary to secondary but with the corresponding decrease in the current. Whereas, step-down transformer decrease the voltage level with the corresponding increase in the current so as to keep the power constant.
You can find more articles related to electrical machines at the following link -
Index of Electrical Machines
Conclusion
Electrical machines are the backbone of modern power systems, enabling energy conversion and efficient electricity usage. Whether it’s generating power with a turbine-driven generator, running appliances with motors, or transmitting electricity with transformers, these devices are crucial in both industrial and everyday applications.