Magnetic Pickups (MPUs) For Sensing Prime Mover Speed

To control the speed of a prime mover, speed controls compare actual speed to desired, or set, speed. The speed sensor most often used to detect prime mover speed is the magnetic pickup (MPU).

When a magnetic material (usually a gear tooth driven by the prime mover) passes through the magnetic field at the end of the magnetic pickup, a voltage is developed. The frequency of this voltage is translated by the speed control into a signal which accurately depicts the speed of the prime mover.