3500/44M Aeroderivative Gas Turbine Vibration Monitor is a four-channel vibration monitoring module under the 3500 Machinery Protection System, specifically designed for aeroderivative gas turbines. It is a critical component of the 3500 series.
The 3500/44M consists of a fixed front card (176449-03) and six configurable rear card options (see the Ordering page for details). The monitor enables real-time monitoring and analysis of key vibration parameters of gas turbines through high-precision signal acquisition and processing. It provides multi-level alarm functions to ensure safe, stable, and efficient operation of the unit. Its design fully considers the high-speed and multi-operating-mode characteristics of aeroderivative gas turbines, supports various sensor inputs and signal conditioning methods, and is widely used for gas turbine monitoring and protection in power generation, oil and gas, marine, and other industries.
Key Features
The 3500/44M monitor offers highly flexible configuration capabilities and multi-parameter monitoring functions. Users can independently configure each channel via the 3500 Rack Configuration Software, supporting the following monitoring and filtering options:
Signal Integration: Supports integration conversion of velocity and acceleration signals.
1X Vibration Tracking: Synchronous filtering based on speed signals to extract vibration components at the same frequency as the rotational speed.
Band-pass Vibration: Configurable high and low cutoff frequencies to extract vibration signals in specific frequency bands.
The monitor supports Multimode Operation. Each channel can be configured with up to eight sets of alarm parameters (including Alert and Danger setpoints and delays), with each set corresponding to a specific machine operating mode (e.g., startup, idle, full load). The system can automatically switch alarm parameter sets based on external I/O contacts or communication gateway commands, adapting to the monitoring needs of gas turbines under different operating conditions.
Additionally, the 3500/44M supports dual Keyphasor® signal inputs, allowing different channel pairs to use different tracking filter reference signals, enhancing system flexibility.
Working Principle
The core workflow of the 3500/44M includes four stages: signal input, conditioning, parameter calculation, and alarm judgment.
Signal Input
The monitor accepts signals from Velomitor® velocity sensors, accelerometers, and Bently Nevada interface modules. Input impedance varies depending on the I/O module type:
Signal Conditioning
Input signals are processed through amplification, filtering, integration, etc., and converted into engineering values (e.g., mm/s, m/s²). The system provides multiple filtering methods:
Direct Signal: 4 Hz – 30 kHz broadband response
Band-pass Filtering: High-pass (25/75/100 Hz) and low-pass (200 Hz) 10-pole filters with a roll-off rate of 200 dB/decade
Tracking Filtering: Based on speed signals, supports a range of 60–240,000 CPM, constant Q value, with optional bandwidth of 3 Hz or 5 Hz
Parameter Calculation
Based on the configured monitoring type, the module calculates the following Measured Values:
Aeroderivative Mode: Direct, 1X Amplitude, Bandpass
Aeroderivative2 Mode: Direct, Bandpass, Bias, 1X Amplitude, 1X Phase Lag
Multimode Aeroderivative Mode: Supports two parallel sets of measured values (e.g., Direct/-B, Bandpass/-B, 1X Ampl/-B, etc.) and operating mode status
Alarm Judgment
Each measured value can set Alert and Danger alarm points with configurable delays:
Alert Delay: 1–60 seconds (in 1-second intervals)
Danger Delay: 0.1 seconds or 1–60 seconds (in 1-second intervals)
Alarm accuracy is as high as ±0.13% of the set value, ensuring timely and reliable response.
Outputs & Communication
Front Panel Indicators: Equipped with OK (operational status), TX/RX (communication status), and Bypass (bypass status) LEDs.
Buffered Transducer Outputs: One coaxial connector per channel, with short-circuit protection.
Recorder Outputs: 4–20 mA current signal, proportional to full scale, independent output per channel, short-circuit does not affect operation.
Communication Interface: Communicates with other modules in the 3500 rack via the backplane, supporting remote monitoring and data integration.
Technical Characteristics
High-Precision Measurement: Typical accuracy for most measurement types is ±0.33% of full scale, with a maximum of ±1%.
Multimode Support: Supports 8 sets of alarm parameters, adapting to various operating conditions of gas turbines.
Advanced Filtering Functions: Includes broadband, band-pass, and tracking filtering, supporting automatic frequency tracking.
Dual Keyphasor® Input: Supports two speed reference signals, enhancing system flexibility.
Multi-Sensor Compatibility: Supports Velomitor®, accelerometers, Proximitor®, and other sensors.
Environmental Adaptability: Operating temperature range from -30°C to +65°C, suitable for harsh industrial environments.
Safety Certifications: Complies with FCC, EMC, LV Directive, RoHS, ATEX, IECEx, CSA, and other international standards for use in hazardous areas.
Physical Characteristics
Monitor Module (Main Board):
Dimensions: 241.3 mm × 24.4 mm × 241.8 mm
Weight: 0.91 kg
I/O Modules:
Dimensions: 241.3 mm × 24.4 mm × 99.1 mm
Weight: 0.45 kg
Rack Space Requirements: Occupies 1 front slot (monitor module) and 1 rear slot (I/O module).
Applications
The 3500/44M is specifically designed for aeroderivative gas turbines in the following fields:
Power Plants: Peaking gas turbines, combined cycle units
Oil & Gas: Compressor set drives, gas turbine power generation
Marine Propulsion: Naval and commercial vessel gas turbines
Industrial Drives: Mechanical drives and emergency generator sets
