Bently Nevada TACH100-01 174652-01 Standalone Digital Tachometer Speed Indicator

The Bently Nevada TACH100-01 (Part Number 174652-01) is a high-precision, microprocessor-based digital tachometer designed for continuous machine speed indication. It operates either as an independent, standalone speed monitor or as a remote indicator connected in parallel with permanently installed turbomachinery protection systems. The instrument incorporates an internal -24 VDC power supply capable of directly driving a Bently Nevada Proximitor sensor, eliminating the need for external loop power in standalone configurations. Alternatively, it accepts signal and common wires from an externally powered Keyphasor proximity probe system via parallel connections at the monitor rack or the probe junction box, processing eddy-current transducer gap voltage variations to compute precise rotor dynamics.

Hardware Specifications

Engineering Notes

• Signal Interfacing: When bridging into an existing machine protection system, connect the TACH100-01 in parallel across the Keyphasor signal and common lines. The high input impedance of the unit prevents loading down the primary monitoring loop or interfering with the OK relay status logic of main rack modules.
• Hysteresis Optimization: Adjust the internal hysteresis pot (0.2 VDC to 2.5 VDC) to eliminate false triggering caused by high-frequency electrical noise, shaft runout, or surface irregularities on the observed target.
• Multi-Tooth Targets: If the speed sensor targets a gear wheel instead of a single keyway, configure the Events Per Turn setting to match the exact tooth count (up to 99) to ensure the internal logic scales down the frequency into accurate direct-reading RPM.

Field Guidelines

• Shield Grounding: Maintain continuous shielding from the Proximitor sensor or Keyphasor probe to the tachometer housing. Ground the cable shield at one end only—ideally at the monitor rack or tachometer chassis—to prevent parasitic ground loops that introduce RPM jitter.
• Power Separations: Route the -24 VDC sensor signal lines in dedicated, grounded conduit segregated from the 110-230 VAC mains power supply wiring to prevent electromagnetic induction.
• Cable Constraints: Observe a minimum bend radius of 50 mm for standard coaxial or twisted-shielded pair transducer cabling during installation to prevent attenuation of high-frequency pulse edges.

Technical & Procurement FAQ

Question: Can the TACH100-01 power a proximity probe when connected to an existing 3500 monitoring system rack?

Answer: No. When interfacing with an existing machine protection system, the probe is already powered by the primary rack monitor. The TACH100-01 must only tap into the signal and common wires in parallel, utilizing its internal high-impedance buffer to read the pulses without drawing loop current.

Question: What happens to the display if the target shaft stops completely or the probe signal drops below the threshold?

Answer: The automatic threshold adjustment dynamically tracks the peak-to-peak gap voltage. If the pulse frequency drops completely out of range or fails to meet the minimum 0.003% display hysteresis shift, the 6-digit LED display stabilizes at 0 RPM.

Question: What is included in the standard shipping box for this specific part number?

Answer: The packaging contains the brand new original Bently Nevada TACH100-01 digital tachometer module, factory-installed 1.5 A slow-blow fuse, and a clear physical technical verification certificate.