Bently Nevada 3500/72-01-00 Rod Position Monitor

3500/72-01-00 Bently Nevada Recip Rod Position Monitor

Product Introduction

The 3500/72-01-00 from Bently Nevada delivers dedicated rod position monitoring for reciprocating compressors. This 4-channel device accepts signals from proximity transducers. It conditions each input to provide both dynamic and static position measurements. Furthermore, it continuously compares these values against user-programmable alarm setpoints. Therefore, operators receive reliable machinery protection and essential diagnostic information for rod position, rod drop, and hyper-compressor applications.

Key Technical Specifications

The 3500/72-01-00 accepts one to four proximity probe signals. Input impedance is 10 kΩ. Nominal scale factors vary by measurement mode. For Rod Position mode, options include 0.79 mV/µm (20 mV/mil), 3.94 mV/µm (100 mV/mil), or 7.87 mV/µm (200 mV/mil). For Rod Position 2, Rod Drop, and Hyper Compressor modes, scale factors are 3.94 mV/µm or 7.87 mV/µm.

Power consumption is 7.7 watts nominal. The monitor channels are programmed in pairs. Additionally, they can perform up to two functions simultaneously. For example, channels 1 and 2 can execute one function while channels 3 and 4 perform another or the same function.

Measured Values and Data Output

The Bently Nevada 3500/72-01-00 returns extensive measured values. For Rod Position Single Channel mode, values include Position Magnitude, Position Angle, Crank Angle, Pk-Pk Amplitude, Gap, 1X Amplitude, Not 1X Amplitude, and 2X Amplitude. For Rod Position Pair Channel mode, similar values are available with additional pairing-specific data.

Rod Drop Channel mode provides Average Piston Position, Average Probe Gap, Instantaneous Piston Position, and Instantaneous Probe Gap. Hyper Channel mode delivers Pk-Pk Displacement, Gap, 1X Amplitude, Not 1X Amplitude, and 2X Amplitude. Consequently, this monitor offers complete visibility into compressor rod behavior.

Frequency Response and Filter Characteristics

The 3500/72-01-00 uses multiple filters for precise signal conditioning. The Peak-Peak filter is fixed at 1 Hz to 600 Hz. The Gap filter is -3 dB at 0.09 Hz. Average piston position also uses a fixed 1 Hz to 600 Hz response.

For single and pair channels, the Not 1X filter uses a Constant Q Notch filter. Minimum rejection in the stopband is 34.9 dB over a frequency range from 60 cpm to 15.8 times running speed. The 1X and 2X vector filters use Constant Q filters with minimum rejection of 57.7 dB. These parameters remain valid for machine speeds from 60 cpm to 2130 cpm.

Accuracy Specifications

The 3500/72-01-00 delivers excellent measurement accuracy. Peak-Peak Amplitude accuracy is within ±0.33% of full-scale typical, with ±1% maximum. Position Magnitude follows the same specification. Rod Position Angle (paired only) achieves within ±1° typical and ±3° maximum. Position Crank Angle also meets within ±1° typical and ±3° maximum.

Gap accuracy is within ±0.33% of full-scale typical. Average piston position and instantaneous piston position share the same high accuracy. Not 1X Amplitude for hyper channels is within ±0.33% of full-scale typical. These tight tolerances ensure reliable alarm decisions and machine protection.

Alarm Configuration and Time Delays

Users configure alarm setpoints using the 3500 Rack Configuration Software. Alarms are adjustable from 0 to 100% of full-scale for each measured value. When the full-scale range exceeds the transducer's range, the transducer's range limits the setpoint. Accuracy of alarm setpoints is within 0.13% of the desired value.

Alert delays range from one to 60 seconds in one-second intervals. Danger delays offer a 0.1-second nominal setting or one to 60 seconds in one-second intervals. Note that OK Channel defeat is disabled for all Rod Position and Rod Drop configurations. For hyper-compressor monitoring, when both transducers are NOT OK, the monitor issues a Danger alarm immediately.

Transducer Power and Buffered Outputs

The 3500/72-01-00 provides a -24 Vdc transducer power supply. Front panel buffered outputs are available via coaxial connectors, one per channel. Output impedance is 510 Ω. Each connector is short-circuit protected for added durability.

Front panel LEDs offer clear status indication. The OK LED lights when the monitor operates properly. The TX/RX LED shows communication activity with other modules in the 3500 rack. The Bypass LED indicates when the 3500/72-01-00 is in Bypass Mode.

Mechanical Dimensions and Environmental Limits

The monitor module measures 241.3 mm x 24.4 mm x 241.8 mm (9.50 in x 0.96 in x 9.52 in). It weighs 0.91 kg (2.0 lb). The I/O module with internal terminations weighs 0.20 kg (0.44 lb). For barrier I/O modules, weight increases to 0.46 kg (1.01 lb).

Operating temperature depends on the I/O module. With internal or external termination Proximitor I/O modules, the range is -30°C to +65°C (-22°F to +149°F). With internal barrier I/O modules, the range is 0°C to +65°C (32°F to +149°F). Storage temperature ranges from -40°C to +85°C (-40°F to +185°F). Humidity tolerance is 95% non-condensing.

Rack Space and Installation

The 3500/72-01-00 requires one full-height front slot in the 3500 rack. The corresponding I/O module occupies one full-height rear slot. Always power down the rack before inserting or removing modules. Use proper grounding techniques for all proximity probe cables. Verify communication using the TX/RX LED after installation.

Packaging List

• 3500/72-01-00 Recip Rod Position Monitor Module (Main Board) – 1 unit

• I/O Module with Internal Terminations – 1 unit

• Installation quick guide

Shipping Information

All orders ship via FedEx, UPS, or DHL. Tracking numbers are provided within 24 hours after dispatch. International shipping is available worldwide.

Frequently Asked Questions (FAQ)

1. Does the 3500/72-01-00 meet API 618 requirements?
Yes, the 3500/72-01-00 meets API 618 requirements for reciprocating compressors. It is specifically designed for rod position, rod drop, and hyper-compressor monitoring applications.

2. How many channels does this rod position monitor support?
The Bently Nevada 3500/72-01-00 supports up to four input channels. Channels are programmed in pairs and can perform up to two different functions simultaneously.

3. What measured values does the rod position mode provide?
Rod position mode provides Position Magnitude, Position Angle, Crank Angle, Pk-Pk Amplitude, Gap, 1X Amplitude, Not 1X Amplitude, and 2X Amplitude. Pair channels include additional pairing-specific data.

4. What is the accuracy of the position measurement?
Position magnitude accuracy is within ±0.33% of full-scale typical and ±1% maximum. Rod position angle accuracy (paired channels) is within ±1° typical and ±3° maximum.

5. What happens during a hyper-compressor transducer failure?
For hyper-compressor monitoring, when both transducers are NOT OK, the 3500/72-01-00 issues a Danger alarm immediately. This ensures immediate notification of critical measurement loss.