What is the significance of the number 120 in the frequency formula for an alternator?

The significance of the number 120 in the frequency formula for an alternator relates to its role as a standard conversion factor for calculating frequency in Hertz (Hz). The formula for determining the frequency in an alternator is given by:

[ \text{Frequency (Hz)} = \frac{N \times P}{120} ]

In this formula, ( N ) represents the speed of the alternator in revolutions per minute (RPM), and ( P ) denotes the number of poles in the alternator. The number 120 is used to convert the product of RPM and pole count into Hertz, where 120 is derived from the relationship that there are 60 seconds in a minute and each cycle is created by two pole passages.

Thus, the number 120 is crucial for ensuring that the calculated frequency is in standard units of Hertz, which is vital for electrical systems that rely on specific frequency tolerances. Without this conversion factor, the frequency calculation would be inaccurate and could lead to improper functioning of electrical equipment.

The other choices touch on different aspects of alternator specifications but do not directly relate to the fundamental calculation of frequency. For instance, while the number of phases is relevant to the electrical output characteristics of the alternator,