Advantages and Disadvantages of AC Transmission

Advantages of AC transmission

1. The power can be generated at higher voltages.
2. The voltage can be stepped up or stepped down easily and efficiently by a transformer . This helps in transmission of power at high efficiency by increasing the voltage level for transmission.
3. Maintenance of AC substations is easy and cheaper.

Disadvantages of AC transmission

1. An AC line requires more copper than that of an equivalent DC line.
2. A three phase AC line requires 3 transmission lines whereas a DC line requires two lines.
3. The construction and analysis of AC transmission line is more complicated than a DC transmission.
4. Due to the presence of skin effect in the AC system the effective resistance of line increases.
5. An AC line has inductance and capacitance. Due to the presence of the shunt capacitance there is a continuous loss of power due to flow of current even when the line is open.

Uninterruptible Power Supplies UPS

Uninterruptible power supplies power maintain continuity in power supply with the help of a battery backup in the event of power failures.

Need for UPS

There are many present a day appliances like

Advantages and disadvantages of DC (Direct current) transmission

Advantages DC (Direct Current) transmission

• Less number of conductors needed as DC transmission requires two conductors where as a three phase AC transmission requires three conductors.
• There is no skin effect in DC and hence the cross section of

Significance of parallel operation of generators

In power plants the generators or alternators of smaller ratings are found to be operated in parallel instead operating of a single large generator capable of supplying the maximum demand on the system. These smaller generating units can be run singly or in various parallel combinations to suit the load demand. The importance of operating the power station in such a manner is

Demand factor

The ratio of maximum demand to the connected load is called as demand factor.

\[Demand factor=\frac{maximum\: demand}{connected\: load}\]

The maximum demand of the system is generally less than the connected load, as all the consumer may

Maximum demand

Maximum demand on a power station

The peak demand of load on the power station over a given period of time is called as maximum demand.

The load on the system varies from time to time and the maximum of all the demands that have occurred during a given period is the maximum demand. It can be observed from the load curve. The given below figure shows the daily load curve in which the peak demand of

Connected load in power system

Connected load

The sum of the continuous ratings of all the equipment connected to the system is called as connected load.

Every consumer in power system will have some electrical equipment being installed. The sum the ratings of all these equipment forms

Load curves in electrical power systems

Load curve

The curve showing the variation of load on the power system with respect to time is known as a load curve.

The load on a power generating station varies widely from time to time and these load variations are recorded under

Classification of Transmission Lines

In Transmission lines, the electrical parameters such as resistance, capacitance and inductance are distributed throughout the length of the conductors. The resistance and inductance form series impedance and the capacitance forms shunt impedances throughout the length of the line. This distributed capacitance introduce complications in transmission line calculations. Based on the manner in which the capacitance is taken into account the overhead transmission lines in power system are classified in to

Feeders in Electrical Power System

In Electrical Distribution system, a feeder is a conductor which connects the sub-station to power distributing area.

There will not be any tapping taken from the feeders so that the current

Circuit breaker

Description of Circuit Breaker

Circuit breaker is a protective device used in power system to protect the system on the event of fault. It isolates the faulty part of the power system in case of the any abnormal conditions. The circuit breaker functions along with a relay which senses

Diversity Factor

In power systems, diversity factor is defined as the ratio of sum of individual maximum demands of all the consumers to the maximum demand of the overall load on the system.

\[Diversity factor=\frac{Sum of individual maximum demands}{Maximum demand of the system}\]

Diversity factor helps in deciding

System

A system is said to be meaningful interconnection of group of independent but interrelated components working coherently to fulfill an objective. For example, an electric fan can be observed as system with its components