The Evolution of Vibration Monitoring
In the early days of industrial machinery protection, engineers relied on handheld probes and subjective judgment to detect bearing wear and imbalance. As rotating equipment grew more complex, the need for precise, continuous vibration data became critical. Today, the Bently Nevada 200155-21-05 Low Frequency Trendmaster Pro represents a major step forward in condition monitoring for slow-speed and fin-fan applications.
Product Overview
The Bently Nevada 200155-21-05 is a Low Frequency Trendmaster Pro accelerometer designed for reliable vibration measurement on slow rotating shafts and fin-fan equipment. Manufactured in the U.S.A., this sensor uses a ceramic shear sensing element housed in 316L stainless steel, ensuring durability in harsh industrial environments. It is used with the ProTIM Option Low Frequency Acceleration-to-Velocity channel type (-05) and carries multiple approvals: CSA, ATEX, and IECEx.
Technical Specifications Breakdown
Sensitivity and Range
At +25°C (+77°F), the 200155-21-05 delivers a sensitivity of 10.2 mV/(m/s²) (100 mV/g) at 80 Hz, with a tolerance of ±12%. Its measurement range spans ±196 m/s² (±20 g), making it suitable for detecting both low-level and moderate vibration signatures.
Frequency Response
Referenced to 80 Hz, the frequency range extends from 1.5 to 10,000 Hz (90 to 600,000 cpm) with a ±10% tolerance. The mounted resonant frequency exceeds 20 kHz (>1200 kcpm), ensuring accurate readings across the operating band.
Electrical Characteristics
Excitation voltage is 4.7 to 5.5 Vdc, with quiescent current below 800 µA. Output bias voltage sits at +2.5 ± 0.23 Vdc. Polarity is defined as SIG+ positive with respect to SIG- when acceleration is from base to connector.
Environmental Durability
Temperature range spans -40 ºC to +105 ºC (-40 ºF to +221 ºF), with hermetic sealing rated at 5X10⁻⁸ atm•cc/s maximum. It withstands 100% relative humidity (condensing, non-submerged) and axial shock up to 49,050 m/s² pk (5,000 g pk).
Industry Applications
Fin-Fan Cooling Towers
Slow rotating fan shafts in fin-fan coolers generate low-frequency vibrations that standard accelerometers miss. The 200155-21-05’s low-frequency response (down to 1.5 Hz) captures early bearing degradation, allowing maintenance teams to plan interventions before catastrophic failure.
Slow Rotating Machinery
For pumps, mixers, and compressors operating below 600 RPM, this accelerometer provides reliable trend data. Its ceramic shear element and low settling time (≤2000 ms) ensure stable readings even after startup transients.
Installation & Setup Guidance
Mount the 200155-21-05 using the 3/8-24 female thread. Apply mounting torque between 2.7 to 6.8 N•m (2 to 5 ft•lbf). The mounting stud option 21 uses a 3/8-24 outer diameter to M6x1 inner diameter 1-3/8 inch hex plate stud. Allow 24 hours cure time after installation. Ensure the sensor is securely fastened to a clean, flat surface for optimal signal transmission.
Maintenance & Reliability
Periodically inspect the sensor and cable for physical damage. The 316L stainless steel housing resists corrosion in humid or chemically aggressive environments. The hermetic seal prevents moisture ingress, maintaining performance even in condensing conditions. Verify output bias voltage periodically to confirm sensor health.
Compatibility & Integration
The 200155-21-05 works with the ProTIM Option Low Frequency Acceleration-to-Velocity channel type (-05). It integrates seamlessly into Bently Nevada monitoring systems for continuous vibration analysis. Its multiple approvals (CSA, ATEX, IECEx) simplify deployment in hazardous areas.
Selection Guide & Purchasing Advice
Before ordering, verify that your monitoring system supports the 200155-21-05’s excitation voltage (4.7 to 5.5 Vdc) and output type. Confirm the mounting thread matches your installation requirements. SpareTechPLC stocks this accelerometer and can advise on compatibility with existing Bently Nevada racks.
Frequently Asked Questions
Q: What is the sensitivity of the 200155-21-05?
A: At 80 Hz, sensitivity is 10.2 mV/(m/s²) (100 mV/g) with a ±12% tolerance.
Q: Can this accelerometer be used in hazardous areas?
A: Yes, it carries multiple approvals including CSA, ATEX, and IECEx.
Q: What is the mounting thread size?
A: The mounting thread is 3/8-24 female. The stud option 21 provides a 3/8-24 outer diameter to M6x1 inner diameter.
Q: What temperature range does it support?
A: Operating temperature range is -40 ºC to +105 ºC (-40 ºF to +221 ºF).
Q: How long does it take to settle after power-up?
A: Settling time is ≤2000 ms (within 5% of bias).
