330750-60-CN Bently Nevada High Temp Velomitor Sensor System

Product Overview

The 330750-60-CN is a specialized Bently Nevada High Temperature Velomitor System designed to measure vibration in extreme heat conditions. Built with a hermetically sealed 300-series stainless steel body, this piezo-velocity sensor enables direct mounting on machine surfaces reaching up to +400°C (+752°F).

The integrated hardline cable on the 330750 Series extends thermal protection from the sensing head to external signal processing hardware. Equipped with a 2-pin Mil-C-5015 hermetic receptacle, it delivers robust isolated output signals over extended cable distances up to 305 meters without signal degradation.

Global PLC Spare HUB's Insight

Gas turbine exhaust casings and steam extraction valves present thermal challenges that damage standard piezo-accelerometers or velocity transducers. In real-world installations, standard soft cables break down quickly when exposed to radiant casing temperatures above 200°C. The 330750-60-CN overcomes this vulnerability by using a 6-meter mineral-insulated hardline cable assembly, maintaining signal stability and physical integrity without requiring forced air cooling.

Configuration Breakdown

• 330750 — Base Model: High Temperature Velomitor System
  • -60 — Cable Length Option: 6.0 meters integral hardline cable line
  • -CN — Agency Approval Option: Country-Specific hazardous area approvals

Technical Specifications

Target Machinery & Applications

• Casing vibration measurement on high-temperature gas and steam turbines.
• Monitoring severe thermal zones near boiler feed pumps and exhaust manifolds.
• Vibration tracking on hot gas expanders and refinery turbo-expanders.
• Condition monitoring on industrial power generation equipment subject to extreme ambient heat.

Diagnostic Capabilities

• Detects structural resonances and imbalance across high-temperature casing environments.
• Monitors mechanical looseness and dynamic unbalance on high-speed rotating shafts.
• Provides clean velocity signals to machinery protection systems without low-frequency noise interference.

Installation Guidance

• Ensure the sensor base mounts flush against clean, flat surfaces to preserve the 5 kHz resonant frequency.
• Observe the 51 mm (2.0 in) minimum bend radius when routing the integral hardline cable.
• Position remote signal electronics in locations where ambient temperatures remain below +121°C (+250°F).
• Protect interconnecting field wiring inside metallic conduit when installing in open outdoor locations.

Commercial Terms & Logistics

Frequently Asked Questions

Q1: What is the main difference between a standard Velomitor and this high-temperature system?

A1: Standard units house signal conditioning electronics inside the probe tip, while the 330750-60-CN separates the high-temp sensing head (+400°C) from the lower-temp signal electronics (+121°C).

Q2: Can the hardline cable be bent during field fitting?

A2: Yes, the mineral-insulated cable accepts manual bends during installation provided you maintain a bend radius of at least 51 mm (2.0 inches).

Q3: Is the sensing head protected against high moisture levels or steam?

A3: The sensing head features a 100% hermetically sealed 300-series stainless steel case, protecting internal components up to 100% relative humidity in non-submerged applications.

Q4: Why does the system output negative bias voltage (-12 VDC)?

A4: Bently Nevada continuous machinery monitoring racks require negative DC bias levels to power internal line driver circuits and detect sensor cable open/short faults.

Q5: What routing caution should technicians take with the signal conditioning electronics unit?

A5: Mount the remote processing enclosure away from direct surface heat so ambient operating temperatures around the electronics module do not exceed +121°C (+250°F).

Tags