Description
Product Introduction & Engineering Value
A machinery protection system does more than detect abnormal conditions. It must also communicate those conditions to shutdown circuits, annunciators, and plant control systems. The Bently Nevada 3500/33 16-Channel Relay Module provides the output interface needed to convert monitoring decisions into reliable relay actions.
Designed for the 3500 Machinery Protection System, the 3500/33 expands rack capability with sixteen independently programmable relay channels. Each output can be configured using Alarm Drive Logic, allowing engineers to build AND/OR voting schemes from Alert, Danger, Not OK, and measured variable conditions.
Technical Specifications
| Parameter | Specification |
|---|---|
| Manufacturer | Bently Nevada |
| Model | 3500/33 |
| Product Type | 16-Channel Relay Module |
| System Platform | 3500 Machinery Protection System |
| Relay Outputs | 16 independent channels |
| Relay Type | SPDT (Single Pole Double Throw) |
| Relay Logic | Programmable Alarm Drive Logic |
| Configuration Software | 3500 Rack Configuration Software |
| Installation Position | Any slot to the right of the TDI module |
| Module Size | Full-height front slot |
| I/O Module Requirement | Full-height rear slot |
| Power Consumption | Approximately 5.8 W typical |
| Operating Temperature | -30°C to +65°C |
| Storage Temperature | -40°C to +85°C |
| Humidity | 95% non-condensing |
| Main Module Weight | Approximately 0.7 kg |
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Field Application & The “Trench” Experience
A compressor station maintenance team received a high vibration alarm from one of their critical machines. The 3500 monitoring channels correctly identified the condition, but the plant shutdown sequence did not initiate during testing.
The troubleshooting process moved downstream from the monitor modules to the relay interface. Engineers found that the existing 3500/33 relay module had intermittent output switching on one channel. Replacing the relay module restored the shutdown path, and the team verified every output channel before returning the compressor train to service.
Typical application scenarios:
- Steam turbine emergency shutdown relay interface
- Centrifugal compressor alarm and trip circuits
- Generator bearing protection annunciation systems
3500/33
3500/33
Transparency SOP: QA & Testing
Every New Surplus or Refurbished Bently Nevada 3500/33 module follows a structured verification process:
- Confirm model identification and hardware revision.
- Inspect relay terminals, connectors, front panel LEDs, and enclosure condition.
- Install the module into a compatible 3500 rack.
- Verify rack communication and module recognition.
- Simulate alarm conditions and confirm relay activation.
- Test relay logic response and channel switching behavior.
- Complete final inspection and ESD-safe packaging.
The Veteran’s Tech Trap Guide
⚠️ Do Not Assume a Relay Failure Is Always Hardware
A relay output problem may originate from incorrect Alarm Drive Logic configuration, incorrect channel assignment, or a changed shutdown philosophy.
⚠️ Check Relay Energization Mode Before Replacement
The 3500/33 supports configurable relay behavior. Normally Energized and Normally De-energized settings must match the original plant design.
PRO TIP:
Before removing the old module, capture the relay configuration file and photograph all field wiring. The replacement hardware is usually straightforward; restoring the exact trip logic is where mistakes happen.
Dynamic FAQ
Q1. What is the Bently Nevada 3500/33 used for?
The 3500/33 provides sixteen programmable relay outputs for the 3500 Machinery Protection System. It is used to send alarm, shutdown, and status signals to external systems.
Q2. How many relay channels does the 3500/33 provide?
The module provides 16 independent relay channels, each configurable for different alarm conditions and voting logic.
Q3. Can the 3500/33 replace a 3500/32 relay module?
Not directly in every application. The 3500/32 provides four DPDT relay channels, while the 3500/33 provides sixteen SPDT relay channels. Replacement depends on the plant shutdown design and wiring requirements.
Q4. Does the module require configuration after replacement?
Yes. Relay assignments, Alarm Drive Logic, and voting settings should be verified using the 3500 Rack Configuration Software after installation.
Q5. Are refurbished 3500/33 modules tested before shipment?
A properly refurbished unit should undergo visual inspection, rack communication checks, relay output testing, and functional verification before shipment.
Q6. Is New Surplus inventory genuine OEM stock?
New Surplus units are unused industrial inventory. Condition verification, inspection records, and warranty terms should be confirmed before purchase.
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