Electrical Motors

1.0 INTRODUCTION :

The experiment shows how to measure a three phase measurement of current, voltage, active power, and power factor at a symmetrical load.

This experiment will illustrate the characteristics of the data acquisition unit and show how it can be used to measure the three phase measurement of current, voltage, active power and power factor at the symmetrical load.

The measurement will be base on a three phase star connection type as shown in the figure below.

Figure 1.1

The method that been use are Two wattmeter technique for measure the current, voltage, active power and power factor. By using the ammeter, voltmeter and wattmeter we can calculate the real power (P), reactive power (Q), apparent power (S) and power factor (pF) by manually. But this method are been replaced into a data acquisition unit that been interface with a PC. So, the required measurement can be done easily in the data Acquisition program. All the connection and the information of this experiment are been detailed in the theory and method.

2.0 OBJECTIVE :-

To measure the three phase measurement of current, voltage, active power and power factor at symmetrical load.

3.0 THEORY :

3.1) Three phase system:

Although single-phase electricity is used to supply common domestic office electrical appliances, three-phase alternating current (ac) systems are almost universally used to distribute electrical power and to supply electricity directly to higher power equipment.

Three-phase electricity consists of three ac voltages of identical frequency and similar amplitude. Each ac voltage ‘phase’ is separated by 120° from the other. This can be represented diagrammatically by both wave forms and a vector diagram (figure 1.2 and figure 1.3 ).

A three-phase system with a common connection is normally drawn as shown below and is known as a ‘wye’ or ‘star’ connection. The common point is called the wye star or neutral point. This point is...