Description:

The 990-05-XX-01-CN​ is a Bently Nevada vibration transmitter from the 990 Series — a two-wire, loop-powered device that takes the input of a 3300 NSv proximity probe and its matched extension cable and converts shaft relative vibration into a proportional 4–20 mA signal. The “05” specifies a full-scale range of 0–5 mils peak-to-peak (0–125 µm pp), “01” specifies 35 mm DIN-rail clips, and “CN” denotes the China-region agency approval and connector configuration.Its defining practical feature is integration: the Proximitor driver electronics live inside the transmitter, so there is no separate proximitor box to buy, mount or wire. 990-05-XX-01-CN​ is aimed squarely at OEMs and end users who need a simple, trustworthy vibration signal feeding a PLC, DCS or SCADA — centrifugal air compressors, small pumps, motors and fans — rather than a full API 670 rack-based protection system. Because the “XX” position is open, the total electrical system length (probe plus extension cable, typically 5.0 m or 7.0 m) must be specified to match the installed transducer; the transmitter is factory-calibrated to that length.

Application Scenarios:

An OEM builds packaged centrifugal air compressors and ships them worldwide. Their customers’ control systems are all different — one plant has a Bently Nevada 3500 rack, another has a generic PLC with spare analogue inputs, a third has a DCS with no vibration card at all. The OEM cannot ship a different monitoring package for every order, and a full rack is not economic on a machine this size.The answer is a transmitter that speaks the universal language: 4–20 mA. 990-05-XX-01-CN​ conditions the probe signal into peak-to-peak vibration engineering units and delivers it as a current loop any control system understands, with alarming and trip logic executed in whatever platform the customer already owns. Two wires carry both power and signal, so installation is one shielded pair per measurement point.The second pain point is subtler and costs plants more money: the false alarm. A vibration transmitter is only as credible as its behaviour when something goes wrong. A loose probe connector or a failed transducer on an ordinary 4–20 mA device can drive the loop upscale and trip a healthy machine — or worse, teach operators to ignore alarms. 990-05-XX-01-CN​ includes a Not OK/Signal Defeat circuit that drops the loop below 3.6 mA within 100 µs when the probe circuit is not healthy, and holds the output below 3.6 mA for 2–3 seconds at power-up. Downstream logic can therefore distinguish “high vibration” from “I can no longer measure” — which is the difference between a protection system and a nuisance.

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