As the armature of a DC motor rotates, an electrical voltage spike is generated every time a brush moves from one commutator segment to the following. It’s called commutation spike and can be used to determine the speed that the motor is rotating at without an encoder.

## How is motor speed measured?

A tachometer (revolution-counter, tach, rev-counter, RPM gauge) is an instrument measuring the rotation speed of a shaft or disk, as in a motor or other machine. The device usually displays the **revolutions per minute (RPM)** on a calibrated analogue dial, but digital displays are increasingly common.

## What is the unit measurement of speed for a DC motor?

The most conventional unit of measuring the speed of a motor is in **RPM**. This stands for revolutions per minutes, or the number of times the motor’s shaft will rotate in one minute. Analogous to this is the second hand on a clock.

## What is 120 in motor speed formula?

The equation for calculating synchronous speed is: **S = 120 f/P speed = constant (120) times frequency of power source (60 Hz) divided by number of poles used in the motor (P)**.

## What is synchronous speed and it’s formula?

The synchronous speed of an AC motor is determined by the frequency of the source and the number of poles. The RPM is **calculated by multiplying the frequency times 60 and dividing by the number of pairs of poles**. Some motors are designed to operate at synchronous speed. …

## What is the maximum speed of DC motor?

The nominal maximum speed and power are **24000 RPM and 0.815 HP**. In particular, these machines must operate loaded in order to avoid damage.

## What is the rpm of 12V DC motor?

**18000 RPM**, 12V DC Motor.