Description

• 4-20 mA analog speed output • SPDT relay output • Internal sensor • User-configurable operating range within 0-9,999 rpm • Setpoint can be set for over-speed or under-speed • Internal LCD for programming and troubleshooting • 24 VDC powered; terminal blocks for easy wiring • Works with Electro-Sensors magnetic pulser discs / wraps • Optional EZ-100 mounting bracket and mounting magnet available • Cast aluminum explosion proof (XP) housing • UL Listed Class I, Div I (C, D) Class II, Div I (E, F, G) Description FB420 is a shaft speed sensor that provides a 4-20 mA output signal directly proportional to the rotational speed of a monitored shaft. Since both the 4 mA and 20 mA calibration points are programmable, the user can also operate the FB420 with the 4 mA point offset from 0 rpm if necessary. The FB420 has a 4-digit LCD display used for calibration and troubleshooting. The LCD is capable of displaying from 0.000 to 9999 rpm or from 04.00 mA to 20.00 mA. The FB420 has one relay that can be programmed for fail-safe over-speed alarm or fail-safe under-speed alarm (the fail-safe ‘alarm’ state is relay de-energized). Housed in a rugged, explosion proof NEMA 4X housing, the FB420 is ideal for detecting shaft under-speed or over-speed on a wide variety of industrial machinery. Typical applications include belt conveyors, drag conveyors, bucket elevators, fans, blowers, crushers, and pumps. Principle of Operation The FB420 is mounted so that the internal sensor is aligned with the magnets that are embedded in either a pulser disc* or a split collar wrap*. Pulser discs are mounted to the end of a shaft. Split collar wraps are attached around the circumference of a shaft. As the shaft rotates, the magnets pass in front of the internal sensor and generate speed pulses. These speed pulses are converted to a 4-20 mA output as programmed by the user. The output relay is energized or de-energized based on the rotational speed of the shaft and the programming of the FB420. Sensor Gap Flexibility You only need a ruler to position our sensing heads (with our competitors you need a feeler gauge). Compare our sensor tolerances to competitors before you purchase.