Description
The Bently Nevada 330400-02-00 is a high-performance casing acceleration transducer engineered for critical turbomachinery and rotating equipment protection. Designed to meet the stringent requirements of the American Petroleum Institute (API) Standard 670 for accelerometers, this sensor converts physical surface acceleration into a proportional analog electrical signal. It is heavily utilized in industrial condition monitoring strategies for diagnostic applications such as gear mesh monitoring, structural vibration tracking, and high-frequency defect detection.
Part Number Configuration Breakdown
The precise model string 330400-02-00 corresponds to the following factory ordering options:
- 330400: Core Accelerometer Transducer Platform (100 mV/g sensitivity).
- -02 (Mounting Thread Option): Equipped with an M8 x 1 integral stud mounting layout.
- -00 (Agency Approval Option): Standard multi-agency approvals envelope (includes CSA, ATEX, and CE general classifications for global hazardous zone deployments).
Technical Specifications
| Parameter | Value / Detail |
| Model Number | 330400-02-00 |
| Transducer Type | Piezoelectric Accelerometer with internal charge amplifier |
| Sensitivity | 10.2 mV/m/s^2 (100 mV/g) \pm 5\% at 100 Hz |
| Acceleration Range | 490 m/s^2 (50 g) peak overall acceleration |
| Frequency Response | 10 Hz to 15 kHz (\pm 3 dB); 30 Hz to 10 kHz (\pm 10\%) |
| Amplitude Linearity | \pm 1\% up to 490 m/s^2 (50 g) peak |
| Mounted Resonant Frequency | >30 kHz minimum (33 kHz typical) |
| Power Requirements | −24 V DC nominal input voltage (\pm 0.5 V DC); 2 mA nominal bias current |
| Output Bias Voltage | −8.5 V DC nominal |
| Connector Interface | 3-pin MIL-C-5015 Receptacle |
| Case Material | 316L stainless steel, hermetically sealed |
| Operating Temperature | −55 to +121 °C (−67 to +250 °F) |
Technical Features & Field Engineering Context
Casing Transmission Dynamics
Because casing acceleration measurements rely on structural transmission, the sensor can only monitor vibration that successfully propagates from the rotating element through the bearing housing to the casing exterior. It is highly effective for high-frequency anomalies like gear teeth impacts, but field engineers must exercise extreme caution if integrating this raw acceleration signal into velocity metrics. For low-frequency applications under 10 Hz or direct machine rotor protection, a dedicated Proximitor loop or a specialized velocity sensor (such as the 330500 Velomitor) should be considered.
Installation and Torque Specifications
Improper mechanical installation will degrade high-frequency response and introduce artificial spectral components due to sensor resonance distortion.
- Torque Limits: The M8 x 1 integral stud must be torqued precisely to 4.1 N·m (3.0 ft·lb). Under-torquing reduces structural coupling stiffness, which dampens high-frequency response; over-torquing risks yielding the mounting threads or damaging the internal piezoelectric crystal assembly.
- Surface Preparation: Ensure the mounting face is machined to a surface finish of 32 \muinch rms or better. Apply a thin film of silicone grease or lubricating oil to the mating surface prior to torquing to eliminate micro-gaps.
- Electrical Ground Isolation: The internal circuit is completely case-isolated. Field wiring shield termination must be tied to a single clean instrument earth ground at the monitoring rack to prevent industrial ground loops from modulating the −8.5 V DC bias baseline.
Commercial and Logistics Status
- Condition: New Original (Factory Sealed in original box) or New Surplus.
- Warranty Period: 12-month comprehensive structural and operational warranty from date of dispatch.
- Global Lead Time: Typically ships within 1 to 3 business days for in-stock surplus inventory.
- Documentation: Factory tracking sheets and calibration data should be cross-referenced with your plant’s plant asset database before swapping live units in safety-critical machinery trip systems.
Commercial Note: Market pricing for specialized Bently Nevada transducers changes according to inventory volumes and manufacturing lead times. The listed price is indicative; contact our procurement team for a firm, itemized commercial quotation.
Frequently Asked Questions
Can this accelerometer be used with a standard 2-wire proximity probe extension cable?
No. The 330400 series uses a 3-pin MIL-C-5015 style connector interface and operates on a 3-wire system topology (Power, Signal, Common Return). It requires dedicated 3-conductor shielded interconnecting cables, such as the Bently Nevada 16710 or 284728 series armored/unarmored assemblies.
What is the significance of the −8.5 V DC output bias voltage?
The −8.5 V DC bias is the nominal quiescent output voltage when the sensor is at rest. Downstream machinery protection monitors track this DC offset voltage continuously. If the voltage drops to 0 V or swings to the supply rail (−24 V DC), the monitor identifies an open or shorted field circuit and flags a “Not OK” status, automatically bypassing machinery trip interlocks to prevent false shutdowns.
How does high-frequency vibration outside the 15 kHz window affect the sensor?
Vibration near or above the transducer’s resonant frequency (>30 kHz) can cause the internal amplifier to saturate. This saturation drastically curtails the usable 50 g dynamic range and introduces intermodulation distortion into the standard 10 Hz to 15 kHz operational window, which leads to erroneous overall vibration values. If high-frequency cavitation or aerodynamic noise is present, external low-pass acoustic filtering or structural isolation may be necessary.
