Bently Nevada 2789-156 Extension Cable Product Specification
2789-156 is a factory pre-calibrated matched coaxial extension cable designed exclusively for Bently Nevada eddy current proximity transducer systems. It serves as the intermediate transmission component linking the integral pigtail of proximity probes and matching proximitor units to build a complete closed-loop measurement circuit, fully complying with API 670 turbomachinery protection standards. This cable is extensively deployed in power generation, petrochemical refining and metallurgical industries for monitoring steam turbines, turbo-generators, centrifugal compressors and large process blowers. It transmits analog voltage signals reflecting clearance changes between probe tip and metallic target to proximitors and subsequent 3500 rack monitoring modules, supporting real-time radial vibration, axial thrust displacement and Keyphasor signal collection, together with equipment early warning and safety shutdown interlock control. Each finished cable undergoes factory continuity testing, impedance matching calibration, insulation resistance inspection and alternating high-low temperature cycling aging before delivery to maintain stable signal transmission amid harsh on-site conditions including high ambient temperature, lubricating oil mist and complex electromagnetic interference.
Description
Bently Nevada 2789-156 Extension Cable Product Specification
1. Product Overview
2789-156 is a factory pre-calibrated matched coaxial extension cable designed exclusively for Bently Nevada eddy current proximity transducer systems. It serves as the intermediate transmission component linking the integral pigtail of proximity probes and matching proximitor units to build a complete closed-loop measurement circuit, fully complying with API 670 turbomachinery protection standards. This cable is extensively deployed in power generation, petrochemical refining and metallurgical industries for monitoring steam turbines, turbo-generators, centrifugal compressors and large process blowers. It transmits analog voltage signals reflecting clearance changes between probe tip and metallic target to proximitors and subsequent 3500 rack monitoring modules, supporting real-time radial vibration, axial thrust displacement and Keyphasor signal collection, together with equipment early warning and safety shutdown interlock control. Each finished cable undergoes factory continuity testing, impedance matching calibration, insulation resistance inspection and alternating high-low temperature cycling aging before delivery to maintain stable signal transmission amid harsh on-site conditions including high ambient temperature, lubricating oil mist and complex electromagnetic interference.
2. Part Number Definition
2789 denotes the base product series of standard calibrated extension coaxial cable for Bently eddy current sensor systems. The suffix 156 specifies fixed factory-calibrated overall length, dual-end connector type, internal coaxial construction and outer sheath configuration, defining exclusive matching parameters for designated probe and proximitor combinations. Non-original or mismatched cables cannot replace this model without invalidating the factory calibration of the entire measurement loop.
3. Core Functional Characteristics
The cable adopts double-layer full-shielded coaxial internal construction to suppress external electromagnetic interference and high-frequency signal attenuation during long-distance signal transfer, preventing measurement drift and linearity deviation of the transducer system. Its outer sheath is made of high-temperature and oil-resistant polymer material to resist mechanical friction, extrusion abrasion and oil corrosion inside bearing housings. Pre-installed gold-plated standard coaxial connectors on both ends enable accurate positioning and reliable locking connection with probe tail plugs and proximitor ports, minimizing intermittent signal faults from poor terminal contact. The full cable length is precisely calibrated at production to preserve the original sensitivity and linear measuring range of the paired proximity measurement system.
4. Electrical Specifications
Compatible with standard Bently proximitor negative DC supply ranging from -17.5VDC to -26VDC, the cable features strictly controlled characteristic impedance and distributed capacitance to match corresponding proximity probe parameters, reducing high-frequency signal reflection loss. Premium internal insulating material delivers high insulation resistance to avoid signal drift induced by dampness or oil infiltration into cable core. All electrical indexes are locked via factory pairing calibration; only designated matching proximity probes and proximitors are permitted for assembly to retain original system measuring accuracy.
5. Environmental Working Parameters
The continuous operating temperature range for the cable body is -40°C ~ +177°C, applicable for high-temperature wiring near bearing pedestals and regular wiring inside control cabinets. Spare part storage temperature is controlled between -55°C and +95°C under non-condensing environment. The applicable working relative humidity spans 5%RH to 95%RH, and surface condensation is forbidden to prevent insulation degradation and core short-circuit risks. The cable can withstand normal industrial vibration from 10Hz to 2kHz generated by operating rotating equipment; long-term continuous exposure to strong corrosive gas and sustained hot steam immersion is prohibited to extend the service life of internal insulation and conductors. For installation locations above 1000 meters altitude, shorten routine inspection cycles appropriately.
6. Installation and Routine Maintenance Guidance
During field installation, arrange cable routing separately from high-voltage power cables and frequency conversion equipment to avoid electromagnetic cross-interference, and reserve proper slack allowance to accommodate thermal expansion and equipment vibration without overstretching the cable. Align connector positioning notches fully before tightening locking nuts to ensure complete connector engagement. In periodic maintenance work, regularly inspect outer sheath integrity, connector fastening tightness and possible sheath cracking or aging damage. When on-site replacement is needed, only original spare cable marked 2789-156 can be directly installed. All replacement cables complete full factory electrical testing and pairing calibration before shipment to guarantee full interchangeability during equipment overhaul and system maintenance.
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