Description
This heavy-duty, case-mounted seismic transducer measures mechanical vibration velocity on rotating machinery by utilizing internal solid-state integration electronics to convert an acceleration signal into a proportional analog voltage output.
Commercial and Supply Chain Status
- Condition: New Original (Factory Sealed) or Refurbished (Tested to OEM Calibration Standards)
- Warranty: 12-Month Industrial Warranty
- Availability: Active stock across primary automation distribution centers
- Lead Time: Ships within 1 to 2 business days from order confirmation
- Pricing: Price scales with localized availability and regional distributor allocations; contact us for a firm quote.
Part Number Breakdown
The specific model configuration string 330500-01-04 maps to the following structural and certification variables:
- 330500: Base model code for the 3300 XL Velomitor Piezo-Velocity Sensor.
- 01: Mounting Thread Stud Option: Equipped with a standard 1/4-28 UNF (Unified Fine Thread) integral mounting stud.
- 04: Agency Approvals: Multiple Approvals configuration, including ATEX/IECEx Zone 0/1 and North American CSA/FM intrinsically safe certifications for hazardous industrial spaces.
Technical Specifications
| Parameter | Value |
| Sensing Element | Piezoelectric ceramic crystal (coupled to a built-in solid-state integrator) |
| Nominal Sensitivity | 3.94 mV/(mm/s) [100 mV/in/s] \pm5\% at 100 Hz |
| Frequency Response | 4.5 Hz to 5,000 Hz (270 to 300,000 cpm) \pm3.0\ dB |
| Velocity Range Peak | 1,270 mm/s (50 in/s peak velocity limits) |
| Excitation Power | Requires −24 V DC nominal bias power channel (−12 V DC to −30 V DC absolute range) |
| Quiescent Current | 2.0 mA to 5.6 mA operating profile |
| Output Impedance | < 100\ \Omega baseline resistance |
| Housing Construction | 316L Stainless Steel (Hermetically sealed case enclosure) |
| Electrical Interface | Top-mounted, 2-pin MIL-C-5015 style threaded connector |
| Operating Temperature | −40 to +121 °C (−40 to +250 °F) |
Functional Architecture and Signal Routing
The 330500 Velomitor replaces older moving-coil velocity pick-ups that rely on physical internal magnets suspended by delicate springs.
- Solid-State Integration: The sensor utilizes a solid-state piezoelectric ceramic element to capture raw acceleration forces. Internal micro-circuitry immediately integrates this charge into a velocity standard (100 mV/in/s) before transmitting the signal down the cable. This design eliminates mechanical wear components, preventing sticking and improving longevity under high-frequency ambient vibration.
- System Connectivity: It routes directly to standard machinery protection racks—such as the Bently Nevada 3500/42M Proximitor/Seismic Monitor—or interface transmitters like the 991 or 1900/65A series. It is widely used to track casing vibrations on balance-of-plant (BOP) machinery including induction motors, centrifugal pumps, cooling tower gearboxes, and industrial blowers.
Engineering Insights: Installation and Mechanical Coupling
Mounting Face Preparation and Torque Limits
⚠️ CRITICAL MECHANICAL INSTALLATION NOTE: Accurate vibration transmission relies on a rigid mechanical connection between the transducer base and the machine casing. The installation spot must be face-milled flat, clean, and properly tapped. Torque the 330500 sensor using its hex flats to a strict specification of 4.6 N·m (41 in·lbf). Under-torquing leads to high-frequency attenuation and signal distortion, while over-torquing deforms the internal crystal seat, introducing permanent bias voltage drift.
Shielding and Ground Loop Isolation
Because the sensor operates on a floating differential signal, preventing electrical noise injection is critical.
- Use a high-quality twisted, shielded two-conductor cable assembly (such as the Bently Nevada 106M6079 series).
- Grounding Rule: Terminate and drain the cable shield exclusively at the monitoring instrument rack side (the 3500 rack ground bar). The shield wire at the Velomitor connector plug must be cut back and insulated to prevent a dual-point ground loop, which can cause electrical noise to show up as false machinery alarms.
Signal Line Troubleshooting
Under normal operating parameters, the Velomitor maintains an operating bias voltage (DC voltage between the signal core and common) between −9.0 V DC and −14.0 V DC.
- If a digital multimeter checks the signal line and returns a value approaching 0.0 V DC, a direct short circuit exists in the field wiring or connector plug.
- A value jumping to the full supply level (near −24 V DC) indicates an open circuit condition, such as a severed cable conductor or a loose pin connection inside the MIL-C-5015 barrel.
Frequently Asked Questions
Q: Can this sensor be plugged into a port configured for a standard accelerometer? A: No. While they both connect via standard 2-pin setups, a conventional accelerometer outputs an unintegrated raw acceleration signal (typically 100 mV/g). The 330500 Velomitor outputs an integrated velocity signal (100 mV/in/s). Connecting it to a channel configured for an accelerometer will cause the monitoring card to calculate incorrect values and trigger a diagnostic fault.
Q: Is it safe to paint the exterior steel body of the 330500 sensor? A: Avoid painting the sensor housing. Heavy coats of industrial paint can trap localized heat or act as an insulating pad that alters the natural resonant frequency of the sensor body, potentially dampening high-frequency transmission checks.
Q: What is the benefit of the Multiple Approvals (-04) designation? A: The -04 suffix ensures the sensor complies with multiple international safety regulations simultaneously. This allows plant managers to use a single unified part number across different global facilities, simplifying spares management while maintaining compliance with local ATEX, IECEx, or CSA intrinsic safety standards.
