Bently Nevada 2789-108 Extension Cable Product Specification
2789-108 is factory pre-calibrated matching coaxial extension cable designed for Bently Nevada eddy current proximity transducer systems. It connects the integral short lead of proximity probes and corresponding proximitor to constitute a complete closed-loop measurement circuit that complies with API 670 turbomachinery protection requirements. This cable is widely applied in power generation, petrochemical and metallurgical industries for TSI monitoring of steam turbines, turbo-generators, centrifugal compressors and large industrial blowers. It transfers analog voltage signals reflecting clearance variation between probe tip and metallic target to proximitors and subsequent 3500 rack monitor modules to realize real-time radial vibration, axial thrust displacement and Keyphasor pulse acquisition, as well as abnormal alarm and safety interlock protection for critical rotating equipment. Each finished cable passes continuity test, impedance matching calibration, insulation resistance inspection and high-low temperature cycling aging test before factory shipment to maintain stable signal transmission under harsh working conditions with high temperature, heavy lubricant oil mist and complex electromagnetic interference inside bearing housings and control cabinets.
Description
Bently Nevada 2789-108 Extension Cable Product Specification
1. Product Overview
2789-108 is factory pre-calibrated matching coaxial extension cable designed for Bently Nevada eddy current proximity transducer systems. It connects the integral short lead of proximity probes and corresponding proximitor to constitute a complete closed-loop measurement circuit that complies with API 670 turbomachinery protection requirements. This cable is widely applied in power generation, petrochemical and metallurgical industries for TSI monitoring of steam turbines, turbo-generators, centrifugal compressors and large industrial blowers. It transfers analog voltage signals reflecting clearance variation between probe tip and metallic target to proximitors and subsequent 3500 rack monitor modules to realize real-time radial vibration, axial thrust displacement and Keyphasor pulse acquisition, as well as abnormal alarm and safety interlock protection for critical rotating equipment. Each finished cable passes continuity test, impedance matching calibration, insulation resistance inspection and high-low temperature cycling aging test before factory shipment to maintain stable signal transmission under harsh working conditions with high temperature, heavy lubricant oil mist and complex electromagnetic interference inside bearing housings and control cabinets.
2. Part Number Definition
2789 refers to the base series of standard calibrated extension coaxial cable for Bently eddy current sensor system; the suffix 108 defines fixed factory-calibrated overall cable length, both-end connector type, inner coaxial structure and outer sheath specification. This configuration is fixed for matched original probes and proximitors, and substitution with unmatched non-original cables will void factory calibration parameters of the whole measurement loop and cause measuring inaccuracy.
3. Core Functional Features
Adopting double-layer full-shielded coaxial inner construction, the cable effectively suppresses external electromagnetic interference and high-frequency signal attenuation during signal transmission, ensuring excellent linearity of the whole transducer system. Its outer sheath is made of high-temperature and oil-resistant polymer material to protect inner insulation and conductors from mechanical scratch, extrusion damage and long-time lubricant corrosion. Standard gold-plated coaxial connectors are pre-installed on two ends for accurate positioning and reliable locking connection with probe tail and proximitor port, greatly reducing intermittent signal faults from poor contact. The fixed overall length is precisely calibrated at production to keep original sensitivity and effective linear measurement range of the matched proximity measurement system.
4. Electrical Specifications
The cable is compatible with standard proximitor negative DC power supply ranging from -17.5VDC to -26VDC. Its characteristic impedance and distributed capacitance are strictly factory-calibrated to match paired proximity probe parameters and reduce high-frequency signal reflection loss. Premium inner insulating material ensures high insulation resistance to avoid signal drift resulting from dampness or oil permeation into cable core. Only designated original matching probes and proximitors can be assembled with this cable to retain factory preset measuring precision.
5. Environmental Working Parameters
Continuous operating temperature of cable body ranges from -40°C to +177°C, suitable for high-temperature wiring near bearing pedestals and conventional indoor cabinet wiring. Spare storage temperature is between -55°C and +95°C under non-condensing environment; applicable working relative humidity covers 5%RH~95%RH and condensation on cable surface is prohibited to prevent insulation deterioration and internal short-circuit. The cable can bear regular industrial vibration of 10Hz~2kHz from running equipment; long-term continuous exposure to strong corrosive gas and persistent hot steam soaking is forbidden to extend service life of inner insulation and conductors. Shortening regular inspection cycle is recommended for installation locations above 1000 meters altitude.
6. Installation and Routine Maintenance Guidance
During field wiring, arrange cable routing away from high-voltage cables and strong magnetic equipment to avoid cross electromagnetic interference, and reserve appropriate cable slack for thermal expansion and equipment vibration instead of excessive tension. Align connector positioning notches fully before tightening locking nuts to realize complete connector engagement. In periodic maintenance, regularly inspect outer sheath integrity and connector fastening tightness to eliminate hidden trouble of intermittent signal loss caused by sheath aging or loose terminals. When replacement is required on site, only spare cable with identical part number 2789-108 is allowed for direct swap. All replacement cables complete full factory electrical calibration and aging test before delivery to guarantee full interchangeability during equipment overhaul.
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