Description
Key Technical Specifications
| Parameter | Specification |
|---|---|
| Manufacturer | Bently Nevada (Baker Hughes) |
| Product Type | Overspeed Monitor Module |
| Model | 3500/53 |
| Part Number | 133388-01 |
| Compatible Platform | Bently Nevada 3500 Series Rack |
| Input Signal | Eddy-current probe or magnetic pickup, +10.0 V to -24.0 V |
| Input Impedance | 20 kΩ |
| Supported Sensors | 3300 8 mm, 3300 16 mm HTPS, 7200 5/8/11/14 mm, 3300 RAM, or magnetic pickup |
| Sensor Supply | -24 VDC, max 40 mA |
| Recorder Output | +4 to +20 mA proportional to full-scale RPM |
| Output Resolution | 0.3662 μA/bit, ±0.25% at 25°C, ±0.7% full temp range |
| Output Refresh | ~100 ms |
| Max Full-Scale Speed | 99,999 RPM |
| Max Input Frequency | 20 kHz |
| Relay Type | SPDT, epoxy-sealed |
| Relay Rating | 5 A max; 30 VDC / 250 VAC; 120 W DC / 600 VA AC |
| Min Switching Current | 100 mA @ 5 VDC |
| Contact Life | 100,000 operations @ 5 A, 24 VDC or 120 VAC |
| Power Consumption | ~8.0 W typical |
| Redundancy | 2oo2 or 3oo2 TMR voting (recommended) |
| Standards | API 670, API 612 (overspeed protection system) |
Product Introduction
Overspeed trips are not the place to discover a mismatched sensor type or an unverified replacement module. The Bently Nevada 3500/53 133388-01 is the overspeed monitor module inside the 3500 machinery protection system, designed to provide fast, redundant speed measurement for turbines, compressors, and other critical rotating equipment.
Each 3500/53 module accepts a single eddy-current or magnetic pickup signal, converts it to a speed measurement, and compares it against software-configured alert and danger setpoints. For true overspeed protection, multiple 3500/53 modules are installed and voted in 2oo2 or 3oo2 logic, with redundant 3500/15 power supplies required in the rack. The module provides a +4 to +20 mA recorder output refreshed approximately every 100 ms, and SPDT relay contacts rated for 5 A switching.
BENTLY 3500-53 133388-01
QA/QC Transparency SOP
- Intake & Origin Verification: Confirm P/N 133388-01, model 3500/53, serial number, and hardware revision. Inspect front-panel connectors, LED indicators, and mounting hardware for damage.
- Live Functional Testing: Install in a compatible 3500 rack with 3500/15 power and 3500/22M TDI. Apply a simulated tachometer signal and verify speed reading, OK LED, and TX/RX communication.
- Electrical Parameter Tests: Measure sensor supply (-24 VDC), recorder output linearity at multiple RPM points, and relay contact continuity in both energized and de-energized states.
- Firmware/Config Verification: Upload existing rack configuration via 3500 Rack Configuration Software. Confirm setpoints, sensor type, events-per-revolution, and voting logic match the protected machine.
- Final QC & Anti-Static Packaging: Verify relay operation, buffered output connector integrity, and label legibility. Pack in ESD-safe materials with documented test results and configuration snapshot.
Field Engineer Gotchas
- Monitor vs. I/O module confusion: 133388-01 is the 3500/53 monitor. The I/O termination is typically 133396-01. Ordering only the monitor without verifying the I/O module can leave you with a card that powers up but cannot connect to field sensors.
- Sensor type mismatch kills trips: Eddy-current and magnetic pickup inputs behave differently at low speed. A module configured for a magnetic pickup will not read correctly from a 3300 XL eddy-current probe without reconfiguration. Verify sensor type in the rack config before commissioning.
- Redundant power is not optional: API 670 overspeed applications require redundant 3500/15 power supplies. A single power supply failure on an overspeed rack is a protection-system event, not a minor alarm.
- TMR voting requires matched modules: A 3oo2 overspeed system needs three properly configured 3500/53 modules. Mixing firmware revisions or setpoint configurations across modules can create voting disagreements or nuisance trips.
- Do not bypass during online testing: The Bypass LED indicates the module is excluded from voting logic. Leaving a module in bypass after maintenance defeats the redundancy the system was designed to provide.
BENTLY 3500-53 133388-01
Application Scenarios
- Steam turbine overspeed protection: Primary electronic overspeed channel for API 612/670-compliant turbine control systems.
- Centrifugal compressor trains: Redundant speed monitoring integrated with ETS/DCS trip logic.
- Gas turbine auxiliary drives: Compact 3500 mini-rack installations where space limits panel footprint.
- Generator set protection: Overspeed detection during load rejection or governor failure events.
FAQ
Is 133388-01 the same as 133396-01?
No. 133388-01 is the 3500/53 overspeed monitor module. 133396-01 is the associated I/O module. Both are typically required for a complete channel.
Can I use a single 3500/53 for overspeed protection?
Technically yes, but API 670 overspeed applications should use redundant modules in 2oo2 or 3oo2 voting. Single-module configurations do not meet recommended protection architecture.
What sensors are compatible?
Bently Nevada 3300 8 mm, 3300 16 mm HTPS, 7200 5/8/11/14 mm, 3300 RAM eddy-current probes, or magnetic pickups. The sensor type must match the module configuration.
Does this module provide relay outputs directly?
The 3500/53 has built-in SPDT relay contacts. For complex trip logic or additional outputs, a 3500/32 or 3500/33 relay module is typically used.
Can I hot-swap a 3500/53?
3500 modules support hot-swapping when the rack is properly configured and redundant protection is maintained. However, removing an overspeed monitor from a live TMR group reduces voting integrity. Follow OEM procedures and site safety rules.
What software is required?
Bently Nevada 3500 Rack Configuration Software (3500/01) is used to configure setpoints, sensor type, events-per-revolution, and voting logic via the 3500/22M TDI.
