3500/61-01-01 Bently Nevada Temperature Monitor

3500/61-01-01 Temperature Monitor with Recorder Outputs

Product Introduction

The Bently Nevada 3500/61-01-01 monitors temperature from up to six channels. It accepts both RTD and thermocouple (TC) inputs. Specifically, the I/O Module Type 01 provides non-isolated internal terminations. The Agency Approval Option 01 adds CSA/NRTL/C certification for Class 1, Division 2 hazardous locations. Power consumption reaches 9 watts nominal for the 3500/61 model.

This monitor includes recorder outputs for each channel. The outputs range from +4 to +20 mA. These signals are proportional to the full-scale value of each channel. Moreover, short circuits on recorder outputs do not affect monitor operation. Front panel LEDs indicate OK, TX/RX, and Bypass status.

Core Value

The 3500/61-01-01 delivers reliable temperature monitoring for rotating machinery. Bearings, windings, and inlet air temperatures are common applications. This module supports seven thermocouple types including E, J, K, and T. Additionally, it accepts four RTD types including 100Ω platinum (alpha 0.00385 and 0.00392), 120Ω nickel, and 10Ω copper.

Input impedance reaches 10 MΩ for each lead input. Therefore, lead wire resistance has minimal effect on accuracy. The RTD current source provides 925 ±15 µA at 25°C. For 3-wire RTDs, two current sources operate. For 4-wire RTDs, a single source works. This design eliminates lead resistance errors effectively.

Furthermore, recorder output resolution reaches 0.3662 µA per bit. Error is only ±0.15% at room temperature. Over the full temperature range, error stays within ±0.4%. Update rate is fast for a temperature monitor. Therefore, this module captures thermal transients accurately.

Technical Insights

The 3500/61-01-01 works with various transducer ranges. For Type K thermocouples, range extends from -18°C to +1370°C. Type T covers -160°C to +400°C. For 100Ω platinum RTD (alpha 0.00385), range goes -200°C to +850°C. Bently Nevada recommends this RTD type as the worldwide industrial standard.

Accuracy depends on termination and rack type. For internal termination non-isolated modules, accuracy is ±3°C at 25°C. External termination non-isolated modules achieve ±1°C at 25°C in standard racks. Meanwhile, isolated I/O modules provide 500Vdc system isolation. Channel-to-channel isolation reaches 250Vdc. However, isolation only matters during fault scenarios. Normal operation does not require these isolation voltages.

Output voltage compliance for recorder signals is 0 to +12 Vdc. Load resistance range is 0 to 600 Ω. Therefore, this monitor drives most recording devices and PLC analog inputs directly. Front panel buffered outputs are not available on temperature monitors. All outputs go through the recorder channels.

Installation & Maintenance

Install the 3500/61-01-01 into a 3500 rack. First, power down the rack or follow hot-swap procedures. Then insert the monitor into a front slot. Slide it carefully along the guide rails. Secure the front screws after full insertion. Next, connect field wiring to the internal termination block.

For RTD connections, use 3-wire or 4-wire configurations. 3-wire RTDs are common for industrial applications. 4-wire RTDs provide better accuracy for critical measurements. For thermocouples, use proper extension grade wire. Maintain correct polarity for each TC type. Also, ensure cold junction compensation works correctly.

After wiring, configure each channel using 3500 Configuration Software. Set transducer type, range, and alarm setpoints. Assign recorder output scaling for each channel. Then verify the OK LED illuminates. The TX/RX LED blinks during configuration download. For bypass mode during maintenance, the Bypass LED confirms active status.

Regular maintenance includes inspecting termination screws. Tighten any loose connections. Also, check for corrosion on thermocouple wires. Replace damaged sensors promptly. Test recorder outputs periodically with a current loop calibrator. Verify each channel outputs +4 to +20 mA across the measurement range.

Buyer’s Guide FAQ

1. How many channels does the 3500/61-01-01 support?
The 3500/61-01-01 supports up to six channels. Each channel accepts either an RTD or a thermocouple.

2. What is the difference between 3500/60 and 3500/61?
The 3500/60 consumes 7 watts and has different I/O options. The 3500/61-01-01 consumes 9 watts and includes recorder outputs.

3. Can I use this monitor with external safety barriers?
Yes, with external barriers the RTD ranges reduce. For 100Ω platinum RTD (alpha 0.00385), range becomes -50°C to +850°C instead of -200°C.

4. Is the 3500/61-01-01 approved for hazardous areas?
Yes, the Agency Approval Option 01 provides CSA/NRTL/C certification for Class 1, Division 2 locations.

5. What happens if a recorder output short circuits?
Monitor operation remains unaffected. Short circuits on recorder outputs do not damage the module. Load resistance must stay within 0 to 600 Ω.