BENTLY 330400-02-00 | 3300 XL Proximity Probe – 5 mm

Description

Product Introduction

The vibration reading jumps. The operator calls. You walk to the machine and see the probe cable is frayed where it exits the case. That’s the 330400-02-00. It’s dead.

The BENTLY 330400-02-00 is the workhorse proximity probe for the 3300 XL system. It’s the sensor that sits 1.5 mm from the shaft and watches it move. It measures vibration, axial position, and speed. When it fails, the monitoring system goes blind.

I’ve replaced these in gas turbines, compressors, steam turbines, and generators. The probes themselves are reliable. The cables are not. The failure mode is almost always the cable—chafed, pinched, or cut. The fix is swapping the probe. One bolt, one cable, one gap setting. Twenty minutes, if the spare is on the shelf.

Key Technical Specifications

Quality Inspection Process (SOP Transparency)

Probes are simple. But they fail in ways that aren’t always obvious.

1. Incoming Verification
   This batch came from a Bently authorized distributor’s final 3300 stock. Sealed boxes. Serial numbers traceable to 2016–2019 production.
2. Visual Inspection
   First: the probe tip. No scratches, no dents, no wear. Next: the cable—look for kinks, cuts, or pinch marks. Roll it between your fingers to feel for flat spots. Check the connector. The threads should be clean, no corrosion.
3. Electrical Test
   We test the 330400-02-00 with a calibrated 3300 XL Proximitor and a precision target stand. Procedure:
   • Connect probe to Proximitor, power up at –24 VDC
   • Position target at 1.5 mm gap (center of linear range)
   • Measure output voltage: should be –10.0 V ±0.1 V
   • Sweep target from 0.25 mm to 2.25 mm, record voltage at 0.25 mm increments
   • Verify linearity: voltage change should be 7.87 V/mm ±0.1 V/mm
   • Cable flex test: bend cable at 90° near the probe and connector, watch for output jumps
4. Insulation Test
   Measure resistance between center conductor and shield. Should be >10 MΩ. Any leakage fails.
5. Final QC & Packaging
   Passed probes go back in anti‑static bags, then bubble wrap, then a carton with QC sticker showing test date, gap voltage, and linearity check.

Field Replacement Pitfalls

Probes are simple. That’s why people skip the steps that matter.

1. Gap setting.
   The probe needs a specific gap—usually 1.5 mm (60 mils) at center of linear range. I’ve seen a plant install a new probe, set the gap by feel, and wonder why the vibration reading was 50% off. Use a feeler gauge or set the gap with the Proximitor.
2. ❌ Cable routing.
   The cable is the weak point. If you run it near hot surfaces or sharp edges, it will fail. I’ve seen a probe last six months because the cable was touching a steam line. The probe was fine. The cable was cooked. Use cable armor if it’s near heat or abrasion.
3. Connector torque.
   The Microdot connector needs to be tight—finger tight plus a quarter turn. I’ve seen a plant with intermittent vibration readings that traced back to a loose connector. The probe was fine. The connection was the problem.
4. Target material.
   The probe is calibrated for 4140 steel. If your shaft is a different material (stainless, chrome‑plated), the sensitivity changes. The reading will be off. I’ve seen a plant chase a high vibration alarm that turned out to be a chrome‑plated shaft throwing off the calibration. The probe was fine. The material was wrong.
5. Probe interference.
   Two probes on the same shaft can interfere if they’re too close—less than 25 mm between tips. I’ve seen a plant with cross‑talk between X and Y probes that made the orbit look like a football. The probes were fine. The spacing was wrong.

Get these five right and you’ll cut rework time by 90%.

New Original vs. Refurbished: Why It Matters

“New Original (New Surplus)” means this BENTLY 330400-02-00 was built by Bently, never installed, and never repaired. The cable is fresh. The probe tip is pristine. The calibration is factory‑fresh.

Refurbished proximity probes are risky. The cable is the weak point. A refurb probe may have a cable that’s been bent, pinched, or heat‑cycled. It will pass a continuity test but fail in the field after a few months. I’ve seen a plant buy a refurb probe that worked for six months, then started giving intermittent signals. The downtime cost was ten times the probe price.

What we provide:

• Traceable serial number (matches Bently production records)
• Full linearity test (0.25–2.25 mm in 0.25 mm steps)
• Gap voltage measurement (–10.0 V ±0.1 V)
• Cable flex test
• Insulation test (>10 MΩ)
• Original anti‑static bag (if available) or fresh bag with QC seal
• 12‑month warranty

Pricing context:
Our price sits above the cheapest used listings. It’s also below what a new probe would cost if Bently still made them. You’re paying for the test, the warranty, and the certainty that the cable isn’t going to fail next month.

Performance Benchmarks & Test Results

All tests performed with 3300 XL Proximitor, 25 °C ambient.

Thermal performance note:
At 150 °C (probe tip), the sensitivity drops about 2%. Still within spec. The cable jacket is rated for 177 °C. If your machine runs hotter than that, you need the high‑temp version. This one will cook.

One more thing from the field:
The 330400-02-00 has a small dot on the probe tip. That’s the center of the coil. When you set the gap, you measure from that dot to the shaft. I’ve seen a tech set the gap from the probe body, which is 3 mm further out. The probe was in the right spot. The gap was wrong. The readings were off. Measure from the dot. It matters.