Bently Nevada ST-5409 Eddy Current Sensor Interface Part Number: 33780-90-00

Description

Bently Nevada ST-5409 Eddy Current Sensor Interface

Part Number: 33780-90-00

1. Product Introduction

The 33780-90-00 is a single-channel, linearized eddy current sensor interface from the Bently Nevada ST-5409 product line. It is designed to drive proximity probes (transducers) and process the RF signal into a proportional DC voltage output. Unlike the 3300 XL series which uses a modern “Click-Lok” connection, the ST-5409 interface (and its associated probes) often utilizes a standard coaxial connection, making it ideal for retrofitting or replacing older 3000 series or 7200 series systems without necessitating the replacement of field wiring or probes. It offers superior RFI/EMI immunity and high-temperature stability compared to legacy units.

33780-90-00

2. Main Technical Specifications

• Part Number Breakdown:
  • 33780: ST-5409 Series Sensor Interface.
  • 90: System Length. This unit is calibrated for a 9.0 meter Total System Length.
  • 00: Standard options (Standard approvals, no special connectors).
• Input Power:
  • Supply Voltage: -23.0 to -26.4 VDC (Unregulated).
  • Current: Approx. 11 mA (typical, excluding load).
• Output Signal:
  • Linearity: ±1% of full scale linear range (typically 80 mils / 2mm for 8mm probe systems).
  • Sensitivity: 7.87 V/mm (200 mV/mil) standard.
  • Output Voltage Range: Typically -2.0 to -18.0 VDC across the linear range.
• Connection Interface:
  • Input: Coaxial connector (Center pin negative, outer shell positive – typical “Reverse Polarity” logic for Bently systems).
  • Output: Screw terminal block for signal out, common, and power.
• Physical Specifications:
  • Housing: Epoxy encapsulated or metal housing (depending on specific revision).
  • Mounting: DIN rail or panel mount adaptable.
• Environmental:
  • Operating Temp: 0°C to +65°C (32°F to +149°F) for the interface module itself (probes can handle higher temps).

3. Typical Applications

The 33780-90-00 is typically used in retrofit scenarios or specialized machinery where long cable runs are necessary:

• Legacy System Upgrades: Directly replacing older 3000 series Proximitors (e.g., 7200 series) without changing the field wiring.
• Long Cable Runs: The “90” (9.0 meter) designation is ideal for large steam turbines or hydro plants where the distance between the probe and the instrumentation cabinet is significant.
• Test Stands & Skids: Used in OEM skids where a cost-effective, reliable vibration monitoring solution is required.
• General Purpose Monitoring: Radial vibration, axial position, and speed measurement on pumps, fans, and small turbines.

4. Avoid Technical Pitfalls (Best Practices & Warnings)

• System Length (9.0m) Verification: The -90 suffix is critical. This interface is electrically tuned for a Total System Length of 9.0 meters. If you install this on a machine with a 5.0m cable run, the sensitivity will be wrong. You must ensure the sum of your probe length + extension cable length equals 9.0 meters, or you will encounter significant measurement errors.
• Connector Compatibility: Verify the connector type on your existing probes. The ST-5409 system typically uses a standard coaxial plug (SMB/SMC style often) rather than the newer “Click-Lok” used by 3300 XL. Do not force a 3300 XL cable into an ST-5409 interface without an adapter, as the pin sizes and grounding configurations may differ.
• Polarity Sensitivity: Bently Nevada systems use a negative DC voltage supply. Reversing the power leads (+24V instead of -24V) will usually destroy the internal electronics immediately. Always verify polarity before powering up.
• Shielding Grounding: The coaxial cable shield must be grounded correctly. In ST-5409 systems, the shield is typically grounded at the Proximitor/Interface end only. Grounding the shield at the probe end can create ground loops, resulting in noisy vibration signals.
• Linear Range Confusion: Ensure the monitor you are connecting to is set for the correct scale factor (200mV/mil). While standard, some custom applications use different sensitivities.

5. Related Product Recommendations

• Proximity Probes: Bently Nevada 300000 series or legacy 7200 series 8mm probes (Must be compatible with ST-5409).
• Extension Cables: 330730 or 330960 series cables (Must sum to 9.0m total length).
• Monitor Modules: Any external monitor accepting standard 4-20mA or buffered voltage inputs (e.g., 3500/40M, 3500/42M, or third-party PLCs).
• Power Supply: Bently Nevada 3500/15 or a standard -24VDC DIN rail power supply.
• Accessories: Terminal blocks, junction boxes, and conduit fittings for field installation.