Bently Nevada 991-25-50-02-00 Thrust Vibration Transmitter
Product Introduction
This Bently Nevada transmitter converts proximity probe signals into a standard current loop. The 991-25-50-02-00 belongs to the 991 thrust transmitter family. It measures axial position on rotating machinery. Furthermore, the unit accepts one non-contacting 3300 NSv proximity probe and extension cable. The 25-0-25 mils full-scale range suits thrust bearing monitoring. Additionally, bulkhead screws secure the unit to a panel or enclosure wall. The transmitter outputs a 4-20 mA signal in a 2-wire configuration. Therefore, plant engineers can feed the signal directly into a DCS or PLC. This device supports condition monitoring for steam turbines and compressors.
Technical Specifications
The 991-25-50-02-00 requires a +12 to +35 Vdc input at the transmitter terminal. The output covers 4 to 20 mAdc over the specified full-scale range. Loop accuracy stays within ±1.5% of full scale, typical. Maximum loop resistance reaches 1,000 Ω including cable at 35 Vdc. Current limiting sits at 23 mA typical. Zero and span adjustments are non-interacting and external. The linear range is 0.25 to 1.65 mm for Prox Out. Specifically, this suits 0.6-0-0.6 mm or 25-0-25 mils current loop linear ranges. The mounting option is bulkhead screws (code 02). The agency approval option is not required (code 00). The system length option is 5.0 meters (16.4 feet) (code 50).
Mechanical and Environmental Parameters
The transmitter operates from -35°C to +85°C (-31°F to +185°F). Storage temperature ranges from -51°C to +100°C (-60°F to +212°F). The unit weighs 0.43 kg (0.9 lbm). A Not OK condition drives the signal output below 3.6 mA within 100 µs. Signal output restores within 0.1 seconds after the Not OK condition clears. The 2-wire configuration reduces wiring cost. Besides, the compact housing fits limited panel space.
Installation Guide
First, secure the transmitter to the panel with the bulkhead screws. Next, connect the 3300 NSv probe and extension cable to the input. Then, wire the 4-20 mA loop to your DCS or PLC. After that, apply +12 to +35 Vdc power at the transmitter terminal. Finally, adjust zero and span using the external controls. Keep loop resistance below 1,000 Ω at 35 Vdc. For instance, verify the TEST signal input against the voltage across a 250 Ω loop resistor. Route signal cable away from heavy electrical noise. Moreover, confirm all terminal connections are tight before startup.
Packaging List
1 x Bently Nevada 991-25-50-02-00 Transmitter
1 x Bulkhead Screw Set
1 x Terminal Block Connector
1 x Installation Reference Sheet
FAQ
Q1: What input does this transmitter accept?
A: The 991-25-50-02-00 accepts one non-contacting 3300 NSv proximity probe and extension cable.
Q2: What is the output signal and power requirement?
A: It outputs 4-20 mA in a 2-wire configuration and requires +12 to +35 Vdc.
Q3: What is the full-scale range?
A: The full-scale option is 25-0-25 mils.
Q4: How is the unit mounted?
A: It uses bulkhead screws, option code 02.
Q5: What happens during a Not OK condition?
A: The output drops below 3.6 mA within 100 µs and restores within 0.1 seconds after the fault clears.
