BENTLY 3500-91M 190782-01

The Bently Nevada 3500 combustion turbine overspeed detection module is a key component in the Bently Nevada 3500 Machinery Protection System family.

Detailed Product Description

1. Product Name & Model Number

• Brand: BENTLY NEVADA (now part of Baker Hughes)

• System Platform: 3500 Series

• Model: 3500/91M

• Part Number / Order Number: 190782-01

• Description: Combustion Turbine Overspeed Detection Module

2. Key Functions

• Overspeed Protection: Continuously monitors turbine rotational speed.

• Dual-Channel Design: The module typically contains two independent monitoring channels (Channel A and Channel B), providing redundancy and enhancing system reliability. If one channel fails, the other can still provide protection.

• Setpoint Alarming: Users can configure one or more dangerous overspeed setpoints. When the speed exceeds these setpoints, the module triggers an alarm.

• Relay Output: The module drives internal relays to output a shutdown signal to the turbine’s control system (e.g., ESD system) to execute an emergency shutdown.

• Self-Diagnostics: The module continuously monitors its own health, including power supply, processor, and circuitry. If an internal fault is detected, it reports to the monitoring module in the 3500 frame and illuminates the fault indicator on the front panel.

3. Key Features**

• High Accuracy: Utilizes high-precision digital signal processing technology to ensure accurate and reliable speed measurement.

• Fast Response Time: For critical conditions like overspeed that require rapid reaction, the module has an extremely fast response time, ensuring a timely shutdown signal.

• Flexibility: Parameters such as setpoints, delays, and alarm logic can be flexibly configured using the framework’s configuration software.

• LED Indicators: The module’s front panel has clear LED indicators showing channel status (e.g., OK, Alert, Bypass, Fault), facilitating quick diagnostics for field personnel.

• Optional TMR Configuration: In applications requiring extremely high safety integrity (e.g., aeroderivative gas turbines), multiple 3500/91M modules can be configured into a Triple Modular Redundant (TMR) system, using a “two-out-of-three” voting logic to further prevent spurious trips or failure to act.

4. How It Works**

1. Signal Input: Receives pulse signals from proximity probes (eddy current sensors) or magnetic pickups installed on the turbine shaft. The frequency of this signal is proportional to the rotational speed.

2. Signal Processing: The module’s internal microprocessor conditions and calculates the input signal to determine the precise speed value.

3. Logic Comparison: Compares the calculated real-time speed against the user-predefined dangerous overspeed setpoint(s).

4. Output Action: When the real-time speed exceeds the setpoint, the processor immediately changes the output state, de-energizing (or energizing, depending on configuration) a relay to generate a “shutdown” contact signal.

5. System Interlock: This shutdown signal is sent to the main control system, which ultimately cuts off the fuel supply to execute an emergency shutdown.

5. Typical Applications**

This module is widely used for overspeed protection in various types of high-speed rotating machinery, especially:

• Industrial Gas Turbines

• Aeroderivative Gas Turbines

• Steam Turbines

• Compressor Drive Turbines

6. Role within the 3500 System**

The 3500/91M module is a Monitoring Module within a 3500 rack. It works in conjunction with the 3500 framework power supply, rack interface module, and relay modules. It does not directly drive external devices but communicates through the backplane to command relay modules within the framework to output the shutdown signal.

Summary

The BENTLY 3500/91M 190782-01 is a high-reliability, high-precision overspeed protection device specifically designed for turbomachinery. It serves as the last, and most crucial, line of electronic defense in protecting expensive large rotating equipment from overspeed damage. Its dual-channel redundant design and robust self-diagnostics ensure stable and dependable protection even in harsh industrial environments.