Panel-Mount Tachometer for Speed Monitoring
The K3HB-RNB 24VAC/VDC: The Omron K3HB-RNB 24VAC/DC is a panel-mount tachometer from the K3HB-R series, designed to display rotational speed or line rate from a sensor input. It accepts no-voltage (NPN open collector) or voltage pulse inputs and counts at up to 50 kHz, which covers most encoder and proximity sensor outputs on conveyor drives, spindle motors, and packaging lines. The LCD display shows two rows of five characters each — a large 14.20 mm main row for the running value and a 4.90 mm secondary row for preset or batch data. Supply is 24 VAC or DC, making it straightforward to power from a common control transformer or 24 VDC bus. The IP66 front-panel rating means the display and bezel withstand washdown spray and dust ingress, so it can be mounted on a machine enclosure in food, beverage, or washdown environments without an additional cover. The panel cutout is a standard 92 mm x 45 mm rectangle, fitting the common 1/8 DIN footprint used across the K3HB family and many other panel meters.
No end-of-life notice or successor part is recorded for this order code at this time. For BOM fill or line-down replacement, the part is available through normal supply — no broker or surplus channel required.
The 50 kHz count rate is the maximum input frequency the internal counter can reliably register. For a 1024 PPR encoder on a motor running at 3000 RPM, the output frequency is about 51.2 kHz — right at the limit. For most applications (proximity sensors on conveyor belts, flowmeter pulse outputs, or lower-resolution encoders), 50 kHz provides generous headroom. The tachometer operates in Up mode only, meaning it counts forward from zero or a preset value; it does not do bidirectional (up/down) counting, so it is suited for speed/rate display rather than position tracking. Reset is external only — there is no front-panel reset button. The reset input must be driven by an external contact or NPN signal, which is typical for automated lines where a PLC or sensor triggers the reset cycle. The screw-terminal connection is direct and tool-friendly for panel wiring.