ELECTRICAL MACHINE | UNIT 1 AC GENERATION

Describe three (3) types of loads in electrical systems.

• Resistive

• Magnetive

• Inductive

• Capacitive

Based on the Faraday’s Law of electromagnetic induction.

Describe steps on how induced currents can be increased

• Moving the coil or the magnet faster

• Using a stronger magnet

• Using dynamo to generate voltage

• Increasing the number of turns

• Split ring commutator generates AC current

Power factor correction (PFC) offers several advantages, including:

• Reduced Energy Costs

• Avoidance of Utility Penalties

• Improved Voltage Regulation

• Reduced System Capacity

• Overloading of Equipment

ADVANTAGES OF AC SYSTEM

• Energy metres, to record the amount of electrical energy used, are much simpler for AC supplies than for DC supplies.

• Direct-current systems does not subject to severe corrosion, which is hardly present with AC supplies

• An alternating-current generator (often called an alternator) is more robust, less expensive, requires less maintenance, and can deliver higher voltages the its DC counterpart.

• Three-phase AC induction motors are cheap, robust and easily maintained.

In a simple DC generator, the current generated is initially alternating but is converted to direct current using a commutator.

• TRUE

• FALSE

Increasing the number of coils in an AC generator typically increases the voltage, but the frequency of the generated current depends on the speed of rotation, not the number of coils.

• TRUE

• FALSE

The direction of current in a DC generator remains constant due to the action of the commutator.

• TRUE

• FALSE

An alternator generates alternating current (AC), not direct current (DC).

• TRUE

• FALSE

In a generator, the faster the coil rotates in the magnetic field, the higher the voltage produced due to increased rate of change of magnetic flux.

• TRUE

• FALSE

Current generation in photovoltaic cells relies on the photoelectric effect, where light photons knock electrons loose from atoms, generating a flow of current.

• TRUE

• FALSE