free-run speed measurement

Features

• Advanced LCD digital display: for easy sensor programming and signal monitoring
• Simple one-touch operation
• Teachable microprocessor: sensor dynamically "learns" the speed of the rotating motor shaft
• Select light-operate, dark-operate, channel display, and timing functions

• Composed of a single sensing end, that both emits a sensing beam and receives reflected light, and bifurcated dual control (sensor) ends which attach separately to the photoelectric sensor
• Constructed with stainless steel braid over monocoil reinforcing wire
• Rugged sheathing provides superior resistance to wear, abrasion, kinking, cutting and snagging
• Lightweight with a tight bend radius

• Adjustable gooseneck arm enables easy positioning of the sensor end to the motor shaft
• Base is equipped with 25 mm T-nuts for mounting to PT Series T-slot Base Plate

Application

Problem
When a motor is coupled to a dynamometer, or any device that has a shaft supported by ball bearings, there will be a small amount of drag load placed on the motor due to friction in the bearings. Ensuring optimal alignment of the motor and dynamometer shafts, as well as using higher-quality bearings and lubricants, can reduce this drag load. However, even when employing these tactics, drag load can never be completely eliminated. All motors will show a slightly greater current draw from the residual drag load, and some motors will show a reduction in free-run speed.

Solution
Magtrol's FR10 Free-Run Speed Sensor is designed for applications where it is necessary to acquire speed readings that are unaffected by drag load. Before connecting a motor to the dynamometer, the free-run speed can be obtained from the FR10 Sensor. With its photoelectric sensor, the FR10 does not need to be attached to the motor but only placed within a ¼ inch of the motor shaft (as shown in the photo to the right). For best contrast, the shaft should be marked with reflective tape.

The sensing end of the fiber optic assembly emits and receives light reflected from the shaft, and sends the speed signal to the fiber optic sensor. The raw speed data is then transmitted to either a Magtrol 3410 Torque Display or DSP6001 Dynamometer Controller where it is converted and displayed in rpms.