Bently Nevada 3300/30 Six-Channel Temperature TC Input Monitor

The Bently Nevada 3300/30 Six-Channel Temperature Monitor is a six-channel temperature monitoring module designed for the legacy Bently Nevada 3300 Monitoring System.
This version is specifically configured to accept Thermocouple (TC) inputs rather than RTD sensors.

It is commonly used to monitor critical temperature points in industrial machinery, including:

• Bearing metal temperature

• Exhaust gas temperature

• Stator winding temperature

• Lube oil system temperature

The monitor provides continuous protection through configurable alarm relays and standard recorder outputs, ensuring reliable thermal supervision in turbine, compressor, and generator applications.

Technical Specifications

1. Inputs

Input Capacity

• Supports up to six (6) independent thermocouple inputs

• Each channel operates independently

Supported Thermocouple Types

• Type J — Iron / Constantan

• Type K — Chromel / Alumel

• Type E — Chromel / Constantan

• Type T — Copper / Constantan

Cold Junction Compensation

• Internal compensation provided at the terminal block

• Automatically corrects measurement drift caused by ambient temperature changes

• Ensures stable temperature accuracy across operating environments

2. Signal Conditioning

Accuracy

• Within ±2.2% of signal, plus thermocouple tolerance

• Reference temperature:
  +25°C (+77°F)

Open Thermocouple Detection

The monitor includes automatic fault detection when a thermocouple circuit opens.

Selectable response modes:

• Upscale drive — Forces reading to high value

• Downscale drive — Forces reading to low value

This feature prevents machinery from operating without temperature protection.

Scan Rate

• All six channels scanned approximately:

0.5 seconds per cycle

This scan speed is typical for machinery protection systems where temperature changes occur gradually compared to vibration signals.

3. Outputs

Recorder Outputs

User-programmable analog outputs:

• +4 to +20 mA

• 0 to -10 Vdc

• +1 to +5 Vdc

Buffered Outputs

Available for diagnostic and monitoring purposes:

• Front panel coaxial connectors

• Rear terminal block connections

• One buffered output per channel

These outputs are typically connected to:

• DCS systems

• PLC systems

• Data recorders

• Condition monitoring software

4. Alarms & Display

Display

• 7-segment LCD temperature display

• Shows real-time temperature value

Channel selection:

• Use the Display button

• Cycles through Channel 1 to Channel 6

Alarm Setpoints

Each channel supports independent alarm configuration:

• Alert alarm

• Danger alarm

Both thresholds are fully adjustable.

OK Indicator

The OK LED continuously monitors system health, including:

• Monitor electronics

• Thermocouple sensors

• Field wiring integrity

Ordering Information

Order Format

3300/30-AXX-BXX-CXX-DXX-EXX

A — Full-Scale Range Option

B — Thermocouple Input Option

C — Alarm Relay Option

D — Agency Approval Option

E — Safety Barrier Option

Engineering & Installation Guide

Space Requirement

The 3300/30 temperature monitor is a:

Double-width module

Installation requirement:

• Occupies two (2) slots in the 3300 rack

This is important when planning rack capacity in retrofit or expansion projects.

Thermocouple Lead Wire Requirement

Always use the correct thermocouple extension wire that matches the thermocouple type.

Examples:

• Type K → Type K extension wire

• Type J → Type J extension wire

Using standard copper wire will introduce:

• Junction voltage errors

• Temperature measurement drift

• Calibration inaccuracy

This is one of the most common field installation mistakes.

Grounding Practice

Recommended grounding method:

Ground the thermocouple shield at the monitor rack only

Avoid grounding at multiple points.

Improper grounding can cause:

• Ground loops

• Signal noise

• Unstable temperature readings

Special attention is required when using:

Grounded-tip thermocouples

These sensors are more sensitive to grounding configuration.

Cold Junction Environment Control

Do not install the monitor rack in locations with:

• Rapid temperature changes

• Strong airflow across terminal blocks

• High thermal gradients

These conditions can affect the accuracy of the internal cold junction compensation.

Typical problematic locations:

• Near ventilation ducts

• Close to turbine exhaust paths

• Outdoor panels without thermal shielding