Blaze Through the FDNY Fire Alarm Supervision 2026 Test (Q-01) – Ignite Your Firefighting Future!

To determine the speed of a six-pole motor operating on a 50-cycle supply, it's essential to use the formula for synchronous speed, which is calculated as:

Synchronous Speed (RPM) = (120 × Frequency) / Number of Poles

In this scenario, the frequency is 50 Hz and the number of poles is 6.

Plugging in these values:

Synchronous Speed = (120 × 50) / 6

= 6000 / 6

= 1000 RPM

This calculation confirms that the correct speed of a six-pole motor at a frequency of 50 cycles (or 50 Hz) is indeed 1000 RPM. Synchronous speed is a key concept in understanding how alternating current motors operate, especially how the speed relates to the number of poles and supply frequency. Therefore, the answer aligns directly with the established electrical principles governing motor operation.