If an old 6-pole motor requires a replacement, what is the rated RPM for a 60 cycle AC motor?

To understand the rated RPM for a 6-pole motor connected to a 60 Hz AC power supply, it is essential to know how the synchronous speed of an AC motor is calculated. The synchronous speed can be determined using the formula:

[

\text{Synchronous Speed (RPM)} = \frac{120 \times \text{Frequency (Hz)}}{\text{Number of Poles}}

]

In this case, the frequency is 60 Hz and the number of poles is 6. Plugging those values into the formula gives:

[

\text{Synchronous Speed (RPM)} = \frac{120 \times 60}{6}

]

Calculating that yields:

[

\text{Synchronous Speed (RPM)} = \frac{7200}{6} = 1200 \text{ RPM}

]

This means that a 6-pole motor operating at 60 Hz will have a synchronous speed of 1200 RPM. It's crucial to identify that synchronous speed is the theoretical maximum speed of the motor, which does not account for any slip that occurs in induction motors when they are running under load. However, for this specific question regarding the rated RPM of a motor,