CA280 144-280-000-125 Meggitt Piezoelectric Accelerometer

CA280 144-280-000-125 is a high-sensitivity piezoelectric accelerometer with a 6-meter integral cable from the Meggitt Vibro-Meter product line. This model belongs to the long-distance integral cable version introduced in the early stages of the CA280 series (approximately 2015 and earlier). It comes standard with a 6-meter low-noise, shielded twisted pair cable (K205 type), with the cable protected externally by a flexible stainless steel braided hose that is hermetically welded to the sensor body, forming a completely sealed integral assembly. This design makes it particularly suitable for applications where the distance between the sensor installation point and the signal conditioner or monitoring cabinet is relatively large, eliminating the need for intermediate connectors and maximizing signal transmission reliability and sealing integrity.

The 144-280-000-125 inherits the core technology of the CA280 series—symmetrical shear mode piezoelectric sensing element, internal case insulation, and differential output—effectively suppressing ground loop interference and ensuring signal quality. Its fully welded AISI 316L stainless steel case provides excellent corrosion resistance and mechanical strength, enabling stable operation within the extreme temperature range of -60°C to +260°C. It has obtained multiple international explosion-proof certifications including ATEX, IECEx, and cCSAus, permitting safe use in potentially explosive gas atmospheres such as Zone 0, 1, and 2.

As an early long-distance integral cable version of the CA280 series, the 144-280-000-125 has been widely applied in large rotating machinery, remote monitoring points, and applications requiring cable routing across hazardous area boundaries, serving as a reliable spare part choice for existing system maintenance and specific functional requirements.

II. Key Features and Benefits

1. Excellent Measurement Performance

• High Sensitivity (100 pC/g) : Capable of accurately capturing微小 vibrations as low as 0.01 g, suitable for precision machinery and structural analysis.

• Wide Frequency Response (0.5 Hz to 6000 Hz) : Covers the vibration frequencies of most rotating machinery while allowing accurate measurement of both low and high-frequency components.

• Low Transverse Sensitivity (≤3%) : Ensures measurement primarily along the sensitive axis, reducing interference from transverse vibrations.

• Low Base Strain Sensitivity (typical 0.8×10⁻³ g/με) : Effectively isolates the influence of mounting surface strain on measurement results.

2. Long-Distance Transmission Integrated Construction

• 6-Meter Integrally Welded Cable Assembly: The cable is welded to the sensor via a stainless steel braided hose, preventing ingress of moisture and corrosive gases, suitable for harsh industrial environments.

• No Intermediate Connectors Required: The 6-meter length can be routed directly from the sensor to the monitoring cabinet or junction box, reducing potential failure points and improving system reliability.

• Fully Welded AISI 316L Stainless Steel Case: Provides excellent corrosion resistance and mechanical strength with high protection level.

• Internal Case Insulation: The sensor is electrically floating relative to the case, avoiding ground loops and improving signal integrity.

• Wide Operating Temperature Range (-60°C to +260°C): Can withstand extreme temperatures, suitable for high-temperature turbomachinery and low-temperature environments.

• Shock Resistance (<1000 g): Able to withstand accidental mechanical shocks, ensuring sensor survival in harsh operating conditions.

3. International Explosion-Proof Certifications

• Multiple Certifications including ATEX, IECEx, cCSAus, EAC: Suitable for potentially explosive atmospheres, including Zone 0, 1, and 2 gas environments.

• Intrinsic Safety Ex ia and Non-Sparking Ex nA: Different protection modes available based on application requirements, ensuring safe operation. The length and capacitance parameters of the integral cable are already included within the Ex certification scope, requiring no additional calculation by the user.

4. Convenient Installation and Connection

• ARINC 554 Standard Mounting: Fixed using three M4 screws with a mounting torque of 4 N·m, no need for electrical insulation of the mounting surface.

• Pre-installed 6-Meter Integral Cable: Factory-welded 6-meter K205 low-noise cable with flying leads at the end, facilitating direct connection to signal conditioners or monitoring systems.

• Suitable for Remote Monitoring: The 6-meter length is sufficient to cover the distance from sensor to monitoring cabinet in most industrial sites, reducing on-site wiring workload.

5. No Subsequent Calibration Required

• Factory Dynamic Calibration: Each sensor is calibrated at 120 Hz, 5 g peak, 23°C, with a sensitivity tolerance of ±5%. No periodic calibration is necessary.

  
  

III. Typical Applications

Leveraging its 6-meter long-distance integrated cable design, high sensitivity, wide temperature range, and explosion-proof characteristics, the CA280 144-280-000-125 is primarily used in the following scenarios:

• Large Rotating Machinery Vibration Monitoring: Such as large turbine-generator units in power plants, gas turbines, compressors, where the sensor installation point is relatively far (3-6 meter range) from the monitoring cabinet.

• Petrochemical Industry: Online vibration monitoring in hazardous areas, with sensors installed on process equipment and monitoring cabinets located in safe areas or at boundaries; the 6-meter cable can directly cross area boundaries.

• Remote Monitoring Points: Such as large fans, pumping stations, conveying equipment, where sensor locations are dispersed and require longer cables to be routed directly to centralized monitoring points.

• Aerospace Test Facilities: Engine test cells, structural test rigs, where distances between sensors and data acquisition systems are significant.

• Existing System Maintenance: Spare part replacement for early-installed 125 versions to ensure system consistency.

• Extreme Environment Monitoring: Long-term vibration monitoring under high/low temperature, high humidity, and corrosive atmospheres; the integral cable ensures sealing integrity.

  
  

IV. Operating Principle and System Integration

1. Operating Principle

The CA280 operates on the piezoelectric shear mode principle: an internal seismic mass applies a shear force to the piezoelectric element under acceleration, generating a charge signal proportional to the acceleration. Due to the differential output and internal insulation, this charge signal manifests as a potential difference between the two pins, effectively suppressing common-mode interference. In the integral cable version, the K205 low-noise cable transmits the differential charge signal from the sensor to the external signal conditioner, and the cable's shielding further suppresses electromagnetic interference. The 6-meter cable length is suitable for scenarios where the distance between the sensor and the monitoring cabinet is relatively large.

2. Signal Conditioning Requirements

As the CA280 outputs a high-impedance charge signal, it must be connected to an external charge converter (such as Meggitt's IPC70x series signal conditioners) or a monitoring system with a charge input. The charge converter transforms the charge signal into a low-impedance voltage signal and may provide functions like integration and filtering, facilitating subsequent data acquisition and analysis. For the 6-meter integral cable version, the cable capacitance is already included in the total load (approx. 9200 pF). When selecting a charge converter, ensure its input capacitance and gain settings are compatible with this cable length. Meggitt's IPC70x series is designed to support long cable transmissions and can be directly matched.

3. System Integration Key Points

• Cable Routing and Fixation: The 6-meter cable is relatively long; plan the routing path carefully to avoid contact with high-temperature surfaces or moving parts. It is recommended to secure the cable using clamps every 300-500 mm to prevent vibration fatigue. Although the stainless steel braided hose is robust, excessive bending (<60 mm radius) may damage the internal cable.

• Crossing Area Boundaries: If the sensor is located in a hazardous area (Zone 0/1) and the monitoring cabinet is in a safe area, use approved flameproof cable glands when the cable passes through the boundary to maintain explosion-proof integrity. The Ex certification of the integral cable considers the cable parameters, but installation accessories require separate certification.

• Grounding and Insulation: The sensor case is electrically connected to the mounting surface, but the internal circuit is insulated from the case. Therefore, no special insulation treatment is required for the mounting surface. System grounding should follow the single-point ground principle to avoid ground loops. The cable shield should be grounded at a single point, preferably at the charge converter end, with the sensor end left floating.

• Wiring Precautions: Use appropriate termination methods for the flying leads, ensuring reliable connection to the shield without causing short circuits. It is recommended to connect the shield to the ground terminal of the charge converter.

• Interfacing with Monitoring Systems: Connect the voltage signal from the charge converter to VM600 monitoring systems, data acquisition cards, or PLC analog input modules. Configure range, alarm thresholds, etc., via configuration software.

  
  

V. Version Positioning and Selection Recommendations

1. Positioning within the CA280 Series

The 144-280-000-125 is an early long-distance integral cable version (6-meter cable length) within the CA280 series. Compared to the later-released 144-280-000-126 (also a 6-meter integral cable version), the main differences might include:

• Part Number Update: 126 likely supersedes 125, but performance specifications are essentially identical.

• Hardware Tweaks: 126 may incorporate updated manufacturing processes or components, not detailed in public documents.

• Certification Continuity: The 126 version maintains the same level of explosion-proof certifications.

2. Comparison with Other Versions

3. Selection Decision Recommendations

• Distance Matching: If the distance between the sensor and the monitoring cabinet or junction box is within the 3-6 meter range, the 125/126 version is an ideal choice, eliminating the need for intermediate connectors. If the distance is less than 3 meters, consider the 115/116 version to reduce cost. If the distance exceeds 6 meters, consider using the sensor-only version with routed extension cables, but ensure the extension solution meets Ex requirements.

• Existing System Spare Parts: If the existing system uses the 125 version, it is recommended to continue procuring 125 or confirm that 126 is directly replaceable (verify mounting dimensions and electrical interface are identical). Since 125 is an early part number, it may have been superseded by 126; consult with Meggitt to confirm compatibility during procurement.

• New Project Selection: For new projects, it is recommended to prioritize currently available integral cable versions (such as 116 or 126), as these versions feature the latest manufacturing processes and ongoing technical support. If the project specifically requires a 6-meter length, 126 is the optimal choice.

• Special Temperature Requirements: If the application temperature exceeds the rating of the K205 cable (-60°C to +260°C), the sensor-only version must be used with special cables having a higher temperature rating.

• Explosion-proof Compliance: The integral cable version, with the cable pre-installed, has the explosion-proof certification covering the entire assembly, making it simpler to use without requiring the user to perform additional cable parameter calculations.

4. Compatibility Notes with Newer Models

The CA280 series may later introduce hardware revision versions (e.g., different suffixes), but basic performance remains consistent. When replacing or mixing, it is recommended to:

• Check if mounting dimensions are identical (especially the ARINC 554 fixing holes).

• Confirm the cable exit direction is the same (radial or axial) to avoid installation interference.

• Verify if explosion-proof certifications cover the required area.

• Note the cable length difference; the 6-meter version cannot be shortened on-site, so sufficient length must be reserved.