# AC fundamentals

## Power Factor Correction Methods

All electrical appliances and industrial equipment consume power at a lagging power factor. The power factor of industrial and commercial installations tends to be low, usually ranging between 0.60 – 0.75 only. The overall power factor of any installation is likely to be below 0.7 unless corrective measures are adopted to improve it.  Due to …

## Three Phase Power Measurement

In ac circuits, power is measured with the help of wattmeter. A wattmeter is an instrument, which consists of two coils called the potential coil (PC) and the current coil (CC). The potential coil having high resistance is connected across the load and carries the current proportional to the potential difference across the load. The current coil …

## Delta Connection

In this method of interconnection, the dissimilar ends of three phase windings are joined together i.e. finishing end of one phase is connected to the starting end of the other phase and so on to obtain a closed circuit. The three line conductors are taken from the three junctions of mesh and are denoted by R, …

## Star Connection

If the three armature coils of a 3-phase alternator are not interconnected but are kept separate, as shown in Figure below, then each phase or circuit would need two conductors, the total number of conductors, in that case, being six. It means that each transmission cable would contain six conductors which will make the whole …

## Power Factor in AC Circuit

In DC circuits, the product VI gives the power in watts drawn by the circuit. But in AC circuits, things are different. In AC circuits, the product VI gives the apparent power and not the real power because the voltage and current are not in phase with each other. Power Factor in AC Circuit The …

## RC | RLC | RL Series Circuits

In actual practice, AC circuits contain two or more than two components connected in series. In a series circuit, each component carries the same current. An AC series circuit may be classified as under: RL Series Circuit  In an RL series circuit, a pure resistance (R) is connected in series with a coil having the …

## Purely Resistive | Inductive | Capacitive Circuit

All AC circuits are made up of the combination of resistance R, inductance L and capacitance C. The circuit elements R, L, and C are known as circuit parameters. To study a general AC circuit it is necessary to consider the effect of each parameter separately. Purely Resistive Circuit  A purely resistive circuit is a …

## RMS Value of AC Current | Derivation

In a DC system, the voltage and current are constant, therefore, there is no problem in specifying their magnitude. But in the case of an AC system, an alternating voltage varies from instant to instant and so poses a problem in specifying the magnitude. So to express the AC quantities in an easy and understandable form, …