Product Short Description
Product Overview
This is an ATEX EX certified low-frequency vibration velocity transducer manufactured by Meggitt Vibro-Meter, designed for absolute casing vibration measurement of low-speed rotating machinery in explosive hazardous zones. The full model coding defines internal circuit configuration, cable interface, explosion protection grade, measuring axis direction, temperature grade and signal output mode. It integrates built-in signal conditioning circuit to eliminate external signal amplifier requirements, delivering linear velocity proportional analog output for long-distance industrial signal transmission.
Description
Core Technical Specifications
- Measurement Principle: Electromagnetic moving-coil velocity sensing + integrated low-frequency compensation circuit
- Nominal Sensitivity: 50 mV/(mm/s) (3-wire voltage output); 50 μA/(mm/s) (2-wire current output)
- Frequency Response: 0.5 Hz ~ 1000 Hz (-3dB low-frequency cutoff compensation)
- Measuring Range: Max peak vibration displacement 2 mm p-p
- Transverse Sensitivity: <5% of main axis sensitivity
- Coil Internal Resistance: 300 Ω with parallel 1500 Ω damping resistor
- Explosion Certification: EX ia IIC T6 intrinsically safe, Zone 0/1 gas hazardous area compliant
- Operating Temperature: -25°C ~ +80°C continuous working
- Storage Temperature: -65°C ~ +120°C
- Power Supply: Passive self-generating coil (no external excitation power required)
- Signal Transmission Distance: Up to 1000 m with shielded twisted-pair EC4xx series cable
- Shock Resistance: 100 g peak short-term mechanical impact
- Weight: 380 g
Functional Features
- Built-in ultra-low frequency correction circuit, stable measurement for hydro turbines, large fans below 10 Hz rotating speed
- Dual signal output modes (voltage/current) compatible with VM600, VMF series monitoring racks
- Full stainless steel sealed housing, IP67 ingress protection against moisture, oil mist and dust
- No external signal conditioner needed, reduces system wiring complexity and signal loss
- Galvanic isolation between sensing coil and metal casing to suppress common-mode industrial EMI interference
- EX intrinsically safe design without ignition risk in flammable gas environments (petrochemical, hydrogen production)
- Single-axis directional measurement, customizable horizontal/vertical installation via model suffix coding
Working Principle
Internal permanent magnet is fixed to the sensor housing; copper coil suspended by elastic spring vibrates synchronously with machine casing vibration. Relative motion between magnet and coil cuts magnetic flux to generate induced voltage directly proportional to vibration velocity. Onboard analog circuit performs low-frequency gain compensation to correct amplitude attenuation below 10 Hz, then outputs standardized voltage/current signal for back-end data acquisition modules. No external power supply is required as mechanical vibration provides complete signal energy.
Material & Structural Characteristics
- Outer Shell: 316L stainless steel, anti-corrosion resistance to sulfur, ammonia and industrial cooling fluid
- Internal Sensing Coil: Oxygen-free copper enamel wire, high-temperature resistant polyimide insulation
- Suspension Spring: Beryllium copper alloy, fatigue-resistant for long-term continuous vibration
- Sealing Structure: Dual-layer fluorine rubber O-ring full sealing; cable gland with metal armor locking
- Mounting Base: Integrated M8 threaded stud, optional magnetic suction base or welded mounting pad accessory
- Terminal Interface: Hermetically sealed glass feedthrough to prevent gas penetration for explosion-proof rating
Installation Requirements
- Mount sensor rigidly on machine bearing housing via threaded stud; magnetic mounting only allowed for temporary spot check (permanent monitoring requires hard mechanical fixation)
- Keep measuring axis aligned with target vibration direction; transverse installation causes over 20% measurement error
- Use shielded EC4xx metal braided cable; connect cable shield single-end to monitoring rack ground (sensor side shield floating)
- Maintain cable bending radius ≥10× cable outer diameter to avoid internal wire breakage
- In explosive areas, cable routing must comply with ATEX conduit isolation standards, no cable joint splices in hazardous zones
- Leave ≥5 cm clearance around sensor housing for heat dissipation; avoid direct contact with high-temperature pipe surfaces over 80°C
Application Scenarios
- Hydroelectric power plant low-speed water turbine, generator bearing casing vibration continuous monitoring
- Petrochemical refinery large low-speed induced draft fans, compressors in Class I explosive areas
- Coal mine ventilation fans, methane pump machinery condition monitoring
- Nuclear power station auxiliary low-speed rotating equipment safety vibration protection
- Offshore platform gas compressors, crude oil pump explosion-proof vibration measurement
Operation & Maintenance Precautions
- Do not drop or apply heavy impact on sensor housing; internal spring suspension suffers permanent deformation above 100 g overload
- Regularly inspect cable armor and sealing O-ring every 6 months in high-humidity environments to prevent liquid ingress
- Strictly prohibit disassembling sensor housing; internal explosion-proof sealing structure will lose certification validity once opened
- Avoid long-term exposure to strong acid/alkaline spray environments without protective cover accessories
- Signal cable must not be routed parallel with high-power AC motor power cables to eliminate electromagnetic crosstalk
- Calibrate sensor sensitivity every 2 years via vibration shaker bench per ISO 16063 standard
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