Product Description

Overview

The Triconex 3511 is a high-performance Pulse Input (PI) module designed for Triple Modular Redundant (TMR) safety systems. Engineered for high-speed monitoring applications, it accurately processes pulse signals from devices such as turbine flowmeters, rotary encoders, magnetic pickups, and proximity sensors. The module ensures precise frequency measurement and rapid response for safety-critical functions in turbines, compressors, and high-speed rotating machinery.

Architecture and Design

3511 uses a TMR architecture with three independent processing legs. Each leg measures the pulse input separately, and the system applies a 2-out-of-3 (2oo3) voting logic to guarantee reliable, fault-tolerant operation. Its design supports SIL 3 safety applications and provides galvanic isolation between channels and between field inputs and system logic to protect the controller from transients and electrical interference.

Performance Highlights

High-Speed Frequency Capture

• Detects pulse signals from 20 Hz up to 20 kHz, covering low-speed sensors to high-speed turbine pickups

• Measurement accuracy ±0.01% of frequency

• Rapid update rate ensures fast response for overspeed and protection logic

Signal Versatility

• Supports NAMUR sensors, dry contacts, and voltage pulses (12–24 VDC)

• Programmable debounce filters to ignore noise and false triggers

• Compatible with both passive (self-generating) and active (powered) sensors

Fault Tolerance and Diagnostics

• Each TMR leg independently counts and processes pulses; system remains operational if a single leg fails

• Continuous self-testing verifies timing circuits and counters without interrupting operation

• Hot-swappable design allows replacement during operation to maximize uptime

Isolation and Protection

• 1500 VAC galvanic isolation between channels and system logic

• Built-in protection against inductive kickback and electromagnetic interference common in turbomachinery

Technical Specifications

Key Application

The 3511 is ideal for overspeed protection and high-speed monitoring in API 670-compliant turbine and compressor systems. Its ability to process pulses from 20 Hz to 20 kHz with millisecond response time ensures that safety-critical devices operate without delay.

FAQ

Q1: How many channels does the 3511 support?
A: The module supports 8 configurable pulse input channels.

Q2: What signal types can it process?
A: NAMUR sensors, dry contacts, and 12–24 VDC voltage pulses.

Q3: Can the module interface with rotary encoders?
A: Yes, it can process incremental encoder signals if frequency and voltage are within specifications.

Q4: Is the module hot-swappable?
A: Yes, the 3511 can be replaced while the system remains powered.