330425-01-CN Bently Nevada Sensor 10 Hz-15 kHz

Bently Nevada 330425-01-CN Accelerometer Specification Guide

Product Introduction

The Bently Nevada 330425-01-CN is a high-performance acceleration transducer designed for predictive maintenance. You can use it to monitor vibration on turbines, compressors, and pumps. This model features a 10.2 mV/m/s² (100 mV/g) sensitivity with a ±5% tolerance. Its frequency response spans from 10 Hz to 15 kHz, covering most critical machinery faults. Additionally, the sensor operates reliably from -55°C to +121°C. The case is hermetically sealed and rated IP68, making it dust-tight and watertight. For users needing country-specific approvals, the -CN option fulfills those requirements. The Bently Nevada 330425-01-CN also provides case isolation to avoid ground loops. Consequently, you get clean, stable signals for your monitoring system.

Technical Specifications

Sensitivity and Range

• Sensitivity: 10.2 mV/m/s² (100 mV/g) ±5%.

• Acceleration range: 490 m/s² (50 g) peak within 10 Hz to 15 kHz.

• Amplitude Linearity: ±1% up to 490 m/s² (50 g) peak.

• Broadband Noise Floor: 0.039 m/s² (0.004 g) rms from 10 Hz to 15 kHz.

The noise floor remains very low, so you can detect small vibration changes. However, vibrations above 15 kHz will reduce the usable range significantly. Therefore, always check your machine's vibration frequency before installation.

Frequency Response

• 10 Hz to 15 kHz (600 to 900,000 cpm) within ±3dB.

• 30 Hz to 10 kHz (1,800 to 600,000 cpm) within ±10%.

This wide response captures both slow roll and high-frequency events. For instance, you can track bearing defects or gear mesh vibrations effectively.

Electrical and Power Requirements

• Input Voltage: -24 ± 0.5 Vdc.

• Bias Current: 2 mA nominal.

• Output Bias Voltage: -8.5 ± 0.5 Vdc.

• Grounding: Case isolated.

• Maximum cable length: 305 metres (1000 ft) with no signal degradation.

Ground isolation prevents unwanted noise from external sources. Furthermore, the long cable capability allows remote monitoring in large facilities.

Mechanical and Environmental Limits

Temperature and Humidity

• Operating and storage temperature: -55°C to +121°C (-67°F to +250°F).

• Relative humidity: 100% condensing, non-submerged.

The hermetically sealed case ensures reliable operation even in humid conditions. Nevertheless, do not fully submerge the sensor.

Shock and Vibration Survivability

• Shock survivability: 49,050 m/s² (5000 g) peak maximum.

• Mounted resonant frequency: Greater than 30 kHz.

• Resonant peak amplitude: 20 dB maximum.

• Transverse sensitivity: Less than 5% of axial.

These robust specs protect the Bently Nevada 330425-01-CN from accidental impacts. Additionally, low transverse sensitivity minimizes measurement errors from side motion.

Base Strain Sensitivity – Important Note

For serial numbers preceded by the letter “G” (including all new sensors):

• 49 mm/s²/mstrain (0.005 g/mstrain).

For serial numbers NOT preceded by “G” (shipped before April 2004):

• 980 mm/s²/mstrain (0.100 g/mstrain) without mounting base.

• 4.9 mm/s²/mstrain (0.0005 g/mstrain) with the supplied API adapter base.

If you own an older unit without the “G” prefix, always use the mounting base. This practice reduces base strain sensitivity significantly.

Magnetic Field and Ingress Protection

• Magnetic field susceptibility: <2.21 mm/s²/gauss (225 mg/gauss) at 50 gauss, 50-60Hz.

• IP Rating: Equivalent to IP68 (dust tight and watertight).

This rating applies to the sensor only, not to the cable. So, protect the cable connection point accordingly.

Physical Dimensions and Mounting

Size and Weight

• Weight (no cable): 99 g (3.5 oz) typical.

• Diameter: 23 mm (0.93 in).

• Height: 59 mm (2.3 in) including mounting stud.

• Case Material: 316L stainless steel.

• Connector: 3-pin MIL-C-5015 receptacle.

Mounting Instructions

• Mounting thread option: 0 1 ¼-28 UNF integral stud.

• Mounting surface finish: 32 minch rms.

• Mounting torque: 4.1 N·m (3.0 ft·lb).

• Mounting angle: Any orientation.

First, clean the mounting surface to achieve the required 32 minch rms finish. Next, apply the recommended torque of 4.1 N·m. Do not overtighten, as this may damage the stud. Finally, you can install the sensor horizontally, vertically, or at any angle without affecting performance.

Installation Guidelines

Preparation Steps

• Inspect the Bently Nevada 330425-01-CN for any visible damage.

• Verify that the mounting surface is smooth and clean.

• Check that the 3-pin MIL-C-5015 connector matches your cable assembly.

Cabling and Power Connections

• Use a suitable low-noise coaxial or twisted-pair cable.

• Maximum cable length is 305 metres without signal loss.

• Connect the -24 Vdc power supply carefully, observing polarity.

• The isolated case does not require an external ground.

For best results, route the cable away from high-voltage lines. This avoids electromagnetic interference. Additionally, secure the cable with strain relief near the connector.

Packaging List

• 1 x Bently Nevada 330425-01-CN accelerometer unit

• 1 x Integral mounting stud (1 ¼-28 UNF)

• 1 x Mounting base (API adapter) – for units without “G” serial prefix

• 1 x Protective dust cap for the 3-pin connector

• 1 x Installation instruction sheet

Note: Cables and connectors are sold separately. No calibration certificates or warranty documents are included in this package.

Shipping and Delivery

• Carriers: FedEx, UPS, DHL

• Packaging: Anti-static foam and reinforced cardboard box

• Tracking: Provided within 24 hours after dispatch

Frequently Asked Questions (FAQ)

1. Q: Can I use the Bently Nevada 330425-01-CN on a slow-speed turbine running at 200 RPM?
A: Yes. The 10 Hz lower limit equals 600 CPM, which covers 200 RPM (200 CPM) only if you use a different sensor with lower frequency. For 200 RPM, we recommend checking the 330425’s 10 Hz limit – it may not capture 3.3 Hz well. Alternatively, use a velocity sensor for very slow speeds.

2. Q: What happens if I exceed the 490 m/s² (50 g) peak acceleration range?
A: The output will clip and become non-linear. Brief overshoots up to 5000 g shock are survivable, but repeated over-range may damage the internal crystal.

3. Q: Do I need an external ground connection for the 330425-01-CN?
A: No. The case is isolated, so you do not need an external ground. Nevertheless, ensure your power supply’s negative terminal is properly referenced.

4. Q: How do I check if my unit has the low base strain sensitivity (G prefix)?
A: Look at the serial number on the sensor’s body. If the first character is the letter “G”, your unit has the improved 49 mm/s²/mstrain rating. Otherwise, use the supplied mounting base.

5. Q: Is the IP68 rating valid when I connect a cable?
A: No. The IP68 rating applies only to the sensor body itself. Once you attach a cable, you must protect the connector junction from prolonged submersion. Use heat shrink or sealed connectors for wet areas.