Product Core Brief
- Model: 79492-01 (3300/45 Temperature Monitor Assembly)
- Brand: BENTLY Nevada
- Series: 3300 Rack Machinery Protection System Line
- Core Function: Accepts RTD and thermocouple inputs across six independent channels, compares measured temperatures against user-defined alarm thresholds, and outputs analog recorder signals for thermal trending of rotating equipment bearings, casings, and lube systems.
- Product Type: Full-slot rack-mount temperature monitoring module
- Key Specs: 6 fully independent thermal input channels | Mixed RTD/TC configurable per channel | Individual 4–20 mA analog recorder outputs | Backplane 24 V DC powered
- Condition: New Original (New Surplus)
Product Introduction
The BENTLY 79492-01 is a full-width rack slot temperature monitor built exclusively for the legacy 3300 machinery protection rack system. It processes thermal sensor signals from critical turbomachinery points and delivers linear analog outputs to plant DCS, recorders, or PLCs for continuous thermal trending and pre-failure overheat alarm logic.This unit supports mixed RTD and thermocouple wiring on separate channels without extra auxiliary signal converters, cutting field wiring hardware count by roughly 35% versus single-type temperature monitor alternatives. Its isolated channel input circuitry suppresses ground-loop thermal measurement noise and caps full-span temperature error at ≤0.3% at 25 °C—though your mileage may vary with long unshielded thermocouple cable runs near high-current motor power wiring.
Key Technical Specifications
表格
| Parameter | Value |
|---|---|
| Rack Slot Format | Full-width single slot for standard 3300 series rack chassis |
| Backplane Supply Voltage | 18 V DC to 32 V DC nominal 24 V DC rack rail power |
| Max Module Steady-State Power Draw | 7.2 W with all six analog outputs loaded |
| Independent Thermal Input Channels | 6 configurable per channel for RTD or thermocouple sensors |
| Supported Sensor Types | Pt100 RTD, Type J/K/T/E/S/R/B thermocouples |
| Analog Recorder Output Per Channel | Isolated 4–20 mA linear temperature signal |
| Alarm Logic Function | User-programmable high/low thermal alarm setpoints per channel |
| Backplane Communication Bus | Proprietary 3300 rack TDXnet interface for system status reporting |
| Continuous Operating Ambient Temp | -40 °C to +70 °C cabinet air |
| Unit Outer Dimensions | 155 mm × 105 mm × 230 mm (H × W × D) |
| Net Assembly Weight | 2.0 kg fully assembled aluminum shielded housing |
| Compliance & Safety Standards | API 670 Rev 4, CE EMC Class A, UL listed for industrial machinery protection |
| Built-In Diagnostics | Open/short-circuit sensor fault detection, backplane power loss monitoring |
Quality Control Process (Engineer’s Perspective)
- Incoming Verification: Cross-reference serial numbers against OEM production logs, scan factory anti-counterfeit QR labels, inspect aluminum housing for bent edges, cracked terminal blocks, or discolored input signal isolation resistors.
- Live Functional Test: Insert the unit into a calibrated 3300 rack, supply nominal 24 V DC backplane power, run a 24 hour stability test cycling simulated RTD/TC temperature inputs across all six channels with 4–20 mA output current logged hourly.
- Electrical Parameter Test: Run 500 V Megger insulation resistance sweep; pass threshold reads >10 MΩ between each sensor input terminal and rack backplane ground plane.
- Firmware Verification: Read and record module internal configuration firmware revision, cross-check 3300 rack software compatibility matrix, photograph terminal screw torque tension consistency.
- Final QC & Packaging: Wipe assembly with anti-static isopropyl wipe, seal inside shielding ESD bag, attach printed QC Passed sticker stamped with exact test completion date.
Replacement Pitfall Guide
❗ Firmware Mismatch: Legacy 3300 rack software Revision 4.0 and older cannot access mixed RTD/TC channel configuration menus on this module. Always upgrade rack configuration software to Revision 5.0 or newer before physical swap.❗ DIP Switch / Jumper Misconfiguration: Factory default channel mode sets all six inputs to Pt100 RTD; thermocouple circuits require manual channel type reconfiguration to avoid flat-line temperature readings.❗ Terminal / Cable Incompatibility: Do not route AC motor power cables parallel to thermocouple input wiring; induced electromagnetic noise creates unstable, drifting temperature measurements.❗ Power Supply Mismatch: Each fully populated 3300 rack with multiple thermal and vibration modules adds substantial DC load; calculate total rack power draw with a mandatory 20% load headroom to avoid backplane voltage droop during startup transients.❗ ESD Damage: Low-humidity winter cabinet air raises static discharge risk by 3.8x. Place a dedicated anti-static foam mat under the rack before hot-swapping this live backplane module.Keep these in mind and you’ll cut 90% of rework time.
Compatibility Matrix & Benchmarks
Compatibility Matrix
- 79492-01 → All 3300 Series Rack CPU, Power Supply, Vibration Monitor Cards : Direct — TDXnet backplane bus match, zero adapter hardware required
- 79492-01 → 3500 Series Rack Chassis : Incompatible — TDXnet bus architecture differs, no direct mechanical or electrical fit
- 79492-01 → External DIN Rail Temperature Transmitters : Needs Adaptation — Requires separate interposing signal isolators to match DCS input voltage/current ranges
Benchmarks
- Full-span temperature measurement linear error: ≤0.30% (24 V DC backplane supply, 25 °C controlled ambient)
- Backplane bus full six-channel status refresh latency: 3.2 ms
- Terminal screw wire cycle durability: 1,000 insert/remove cycles with no contact resistance shift exceeding 0.12 Ω
