1 Year Warranty
Description
3500/64M 176449-05 — Dynamic Pressure Monitor
Product Overview
The 3500/64M 176449-05 is a single-slot, four-channel Dynamic Pressure Monitor from Bently Nevada, a Baker Hughes business, purpose-built for the machinery protection problem that ordinary vibration monitors cannot see: combustion dynamics. It accepts inputs from one to four high-temperature dynamic pressure transducers mounted on gas turbine combustors or engine cylinders, conditions each signal into a bandpass dynamic pressure value, and continuously compares that value against user-programmable alert and danger setpoints to drive alarms.
The module’s design centers on filtering. Each channel produces one measured variable — bandpass dynamic pressure — with corner frequencies configured through the 3500 Rack Configuration Software, plus an additional line-rejection notch filter set for 50 or 60 Hz. Two filter modes serve the two distinct measurement tasks: Low mode (5 Hz to 4 kHz) for the pulsation frequencies of combustion instability, and High mode (10 Hz to 14.75 kHz) for the wider bandwidth of high-speed pressure events. Channels work in pairs, and a Cascade Mode lets a single transducer feed all four channels, each with its own filter and full-scale range.
The 176449-05 part number is the official spare designation for the monitor itself, matched with separately ordered I/O modules and external termination blocks. For operators of gas turbines, the module answers a specific question no other monitor in the rack can: whether the pressure dynamics inside the combustor are approaching the region where hardware damage begins — and it answers it with protection-grade alarms, not just diagnostic data.
Technical Specifications
| 参数名称 | 参数值 |
|---|---|
| Product Model | 3500/64M 176449-05 |
| Manufacturer | Bently Nevada, a Baker Hughes business (USA) |
| Product Type | 4-channel Dynamic Pressure Monitor, 3500 Machinery Protection System |
| Inputs | 1–4 high-temperature dynamic pressure transducer signals |
| Input Impedance | 10 kΩ (3-wire); 1.5–3.5 MΩ typical (2-wire) |
| Transducer Supply | -24 Vdc (3-wire); 3.3 mA current source @ 22 Vdc (2-wire) |
| Measured Variable | Bandpass dynamic pressure (direct value per channel) |
| Filter Modes | Low 5 Hz–4 kHz; High 10 Hz–14.75 kHz; 50/60 Hz line-rejection notch |
| Recorder Outputs | +4…20 mA per channel, 0–600 Ω load, 0–12 V compliance |
| Buffered Outputs | Per-channel coaxial, 550 Ω, short-circuit protected |
| Alarm Setpoints | 0–100% of full scale; accuracy within 0.13%; delays 0.1–60 s |
| Operating Environment | -30…+65 °C (standard I/O); storage -40…+85 °C |
| Physical / Compliance | 241.3 × 24.4 × 241.8 mm, 0.82 kg; FCC, EMC/LVD/RoHS, DNV GL, ABS; cNRTLus / ATEX-IECEx options |
3500/64M 176449-05
Key Features and Advantages
Filtering engineered for combustion dynamics: The 10-pole high- and low-pass filters in Low mode deliver 200 dB per decade roll-off, with a fixed low-pass stopband of -78 dB minimum — the selectivity needed to separate a combustor instability tone from broadband noise. The steep skirts are what make this monitor usable as a protection device rather than a lab instrument.
Cascade mode turns one transducer into four measurements: In the 1>ALL mode, a single pressure transducer feeds all four channels, each configured with a different bandpass and full-scale range. A plant can watch a broad instability band, a narrow risk band, and two diagnostic windows on the same physical sensor, maximizing the value of each expensive high-temperature probe.
Two wire schemes, one module: The 3500/64M drives 3-wire transducers with -24 Vdc and 2-wire transducers with a 3.3 mA current source at 22 Vdc nominal, so it matches the two dominant pressure-transducer conventions without external conditioning hardware.
Protection-grade alarm handling: Alert and danger setpoints are adjustable across 0–100% of full scale, hold within 0.13% of the desired value, and carry programmable time delays from 0.1 to 60 seconds — the combination of accuracy and delay flexibility that lets engineers set real protection thresholds without tripping on transients.
Built for control-system integration: Each channel provides an individual +4…20 mA recorder output, isolated from short circuits, with 0–12 V compliance across 0–600 Ω, so the module feeds a plant DCS or control system directly without a separate transmitter card.
Diagnostics without compromise: Per-channel buffered transducer outputs at 550 Ω let an engineer connect an analyzer to examine the live pressure waveform while protection continues uninterrupted — essential when validating combustion dynamics during commissioning.
Certified where gas turbines actually run: With cNRTLus Class I Division 2 / Zone 2 and ATEX/IECEx approvals, plus DNV GL and ABS marine classification, the 3500/64M is approved for the offshore platforms and gas plants where combustion monitoring matters most.
Application Areas
The 3500/64M exists primarily for one application: identifying and tracking gas turbine combustor instabilities. Dynamic pressure transducers on the combustor shells report the pulsations that precede hardware damage, and the module turns those signals into bandpass values that drive alarms — protecting liners, transition pieces, and turbine inlet components from the consequences of undetected combustion dynamics.
The same hardware extends to engine cylinder pressure monitoring in reciprocating machines, using the Cylinder Pressure I/O module option, where the measured dynamic pressure supports both protection and the diagnostic record of each cylinder’s behavior. In hydroelectric plants, the module’s measurement approach appears within the 3500/46M Hydro Monitor, which processes dynamic pressure alongside vibration for detecting draft-tube pulsation and rough load zone conditions.
Compressor packages and pump systems use dynamic pressure channels to detect pulsation and flow instabilities that appear as pressure fluctuations rather than casing vibration. On offshore platforms and gas plants, the certified variants mount directly in the classified-area cabinets, keeping the protection function local to the machine. In every case the 3500/64M holds the same role in the rack: it monitors the pressure dynamics that other channels cannot sense, and it does so with the same alarm discipline as the vibration and position monitors around it.
Related Products
- 140471-02 — I/O module with internal termination; the rear-slot companion for the 3500/64M monitor.
- 140482-02 — I/O module with external termination; same role for field-wired terminations.
- 143729-01 — Cylinder Pressure I/O module with internal termination, for engine cylinder pressure measurement.
- 128015-09 — Dynamic Pressure external termination block with terminal-strip connectors.
- 125808-09 — Dynamic Pressure external termination block with Euro style connectors.
- 128710-01 — Recorder Output external termination block (terminal strip) for the 4…20 mA outputs.
- 35050 — Bently Nevada charge amplifier used with dynamic pressure transducers in the 3500 measurement chain.
- 350300 — Bently Nevada dynamic pressure sensor for hydro and pump pulsation measurements (piezo-resistive, up to 2 kHz).
- 3500/46M — Hydro Monitor that processes dynamic pressure together with vibration and air-gap signals for hydro turbine protection.
Installation and Maintenance
Installation preparation: Order the 3500/64M 176449-05 with the correct I/O module option — 140471-02 for internal terminations or 140482-02 for external terminations — and confirm the approval option matches the plant’s hazardous-area classification, since barrier and non-barrier I/O variants follow different installation drawings. Install the monitor in a full-height front slot of the 3500 rack and the matching I/O module in the rear slot. Wire the pressure transducers according to their supply type — -24 Vdc for 3-wire, the 3.3 mA current source for 2-wire — using the appropriate external termination block and cables (129525 for the signal, 129529 for recorder outputs). Program the channels with the 3500 Rack Configuration Software: select Low or High filter mode consistently within each channel pair, set the bandpass corner frequencies and the 50/60 Hz notch, assign full-scale ranges, and configure alert and danger setpoints with suitable time delays before energizing the machine.
Maintenance advice: Use the front-panel LEDs as the daily health check — OK for module health, TX/RX for rack communication, and Bypass for maintenance bypass states that must be cleared before the machine returns to full protection. During outages, verify the recorder outputs against a calibrated 4…20 mA source and confirm that the buffered transducer outputs track the live pressure signal on an analyzer. If combustion dynamics alarms behave erratically, check the notch filter setting and the integrity of the transducer cable before suspecting the monitor, since high-temperature transducer cabling is the most failure-prone element of the loop. Keep a documented spare 176449-05 with the matching I/O module per turbine family, and handle all board insertion with the supplied grounding wrist strap to protect the module’s sensitive analog front end.
Product Warranty
The 3500/64M 176449-05 is supplied with the Bently Nevada standard warranty, with new and tested surplus units verified against the official datasheet — channel count, filter response, recorder output resolution, and environmental ratings — before shipment. Units carry the certification documentation appropriate to their approval option, including cNRTLus or ATEX/IECEx markings and the referenced installation drawings, so a replacement preserves the protection system’s approval basis. Because 176449-05 is the manufacturer’s own spare designation for this monitor, the supply chain can deliver configuration-matched replacements, companion I/O modules, termination blocks, and application support for filter and setpoint configuration — keeping combustion dynamics protection operational, documented, and supported for the life of the gas turbine fleet.
