Description

Bently Nevada 81PS1F68‑8 Speed / Phase Monitor Module

Technical Specifications

• Product Model: 81PS1F68‑08 (81PS1F68‑8)
• Brand: Bently Nevada (Baker Nevada, 3500 Machinery Monitoring System)
• Warranty: One Year
• Input Voltage: 24 VDC (18‑30 VDC), rack‑backplane powered; typical consumption 230 mA
• Operating Temperature: 0 °C ~ +60 °C rack‑mount
• Storage Temperature: ‑40 °C ~ +85 °C
• Response Time: Input signal bandwidth 1 Hz‑20 kHz for rotating‑machine pulse pickup
• Protection Class: IP20, cabinet‑only indoor installation
• Accuracy Class: Speed measurement ±0.05 % full‑scale
• Output Frequency: Accept machine rotating‑frequency 10‑20000 RPM; buffered pulse output
• Rated Channels: 2‑channel speed / phase input for magnetic pickup or proximity key‑phasor signal
• Signal Interfaces: Magnetic pickup / key‑phasor input; buffered pulse output; configurable alarm relay outputs
• Diagnostics: Input signal amplitude monitoring, cable fault detection; front‑panel multi‑color LED indicators
• Galvanic Isolation: Field‑sensor side vs system backplane 1000 VAC isolation rating
• Mounting: Standard Bently Nevada 3500‑series rack slot form‑factor
• Dimensions / Weight: 225 mm × 170 mm × 28 mm; approx 0.62 kg
• 

Product Overview

The 81PS1F68‑8 is a speed‑phase monitor module for Bently Nevada 3500 machinery protection system. It conditions pulse signals from magnetic pickups or key‑phasor proximity probes, measuring rotating‑equipment shaft rotational speed and phase angle for gas turbines, steam turbines, compressors and centrifugal pumps. It converts raw pulse signals into usable RPM value, provides buffered monitoring outputs for host system, and executes real‑time alarm and trip logic for over‑speed protection. Built‑in diagnostics detect sensor open‑circuit, short‑circuit and low‑amplitude signal faults. High‑grade galvanic isolation protects rack electronics from field‑side voltage surges and ground‑loop noise, delivering stable performance in heavy‑EMI power‑plant and petrochemical cabinet environments.