Which instrument determines the speed of a direct drive fan motor?

The tachometer is the instrument specifically designed to measure the speed of a rotating device, such as a direct drive fan motor. It provides a direct readout of the motor's RPM (revolutions per minute), allowing for precise monitoring and adjustment of the fan's operational speed.

In applications involving direct drive fans, maintaining the correct speed is crucial for ensuring optimal performance and efficiency. The tachometer's capability to provide real-time feedback on motor speed enables operators to verify that the system is functioning as intended.

In contrast, a voltmeter measures electrical potential (voltage) in a circuit, which does not directly indicate the speed of the fan motor. A manometer is used to measure fluid pressure, which could be related to airflow but is not relevant for assessing motor speed. An anemometer measures the velocity of air or gas flow rather than the rotational speed of the fan motor itself. Thus, the tachometer stands out as the most appropriate tool for determining the speed of a direct drive fan motor.