Triconex 3636R Relay Output Module: A Field Engineer’s Guide to High-Density Safety Switching

2026-04-02

ExcerptNavigate the technical complexities of the Triconex 3636R. This guide provides essential selection criteria, wiring strategies, and troubleshooting tips for deploying high-density relay logic in critical Safety Instrumented Systems (SIS).

The Triconex 3636R is a high-density, 32-channel Relay Output module designed for the Triconex Safety Instrumented System (SIS). Its primary function is to switch field loads—such as solenoid valves, indicator lights, and small motor starters—based on logic solver commands. In industries like oil and gas and power generation, the 3636R solves the critical pain point of cabinet space optimization without sacrificing safety.

Unlike standard 16-channel relay modules, the 3636R packs 32 channels into a single slot. This “Simplified” (Non-TMR) architecture is designed for applications where the safety integrity is managed at the logic level (e.g., 2oo3 voting in the processor) rather than requiring redundant relays for every single output. It allows engineers to control a vast array of field devices while significantly reducing the physical footprint of the control cabinet.

Technical Insights: Decoding the Specifications

To maximize the effectiveness of the 3636R, you must understand three key technical parameters that influence system design and safety.

1. High Channel Density (32 Points per Module)

The module provides 32 independent relay contacts in a single form factor.

Impact: This density effectively doubles your output capacity per rack slot compared to older modules (like the 3601E). However, this requires rigorous cable management. You must ensure your marshalling panels and terminal blocks can handle the sheer number of wires (32 outputs + commons) associated with a single module to prevent congestion and heat buildup.

2. Non-Commoned (Form C) Architecture

The 3636R features “Non-Commoned” relay outputs, meaning each channel has independent Common (C), Normally Open (NO), and Normally Closed (NC) terminals.

Impact: This offers maximum wiring flexibility. You can mix different voltage levels on the same module (e.g., 24VDC for solenoids on channels 1-16 and 110VAC for indicators on channels 17-32) without worrying about shorting different commons together. This isolation is critical for retrofitting brownfield sites where field wiring standards may vary.

3. Load Ratings (2A @ 125 VAC/VDC)

The relays are rated for a continuous current of 2A with a voltage range up to 125 VAC/VDC.

Impact: This rating is sufficient for most instrument-grade loads (solenoids, relays, contactors). However, for larger inductive loads (like large AC motors), you must use an external interposing relay. Directly switching high-current loads can cause contact welding or arcing, which would degrade the safety function of the module.

Field Installation and Maintenance Guide

Working with high-density relay outputs requires precision. Here are field-tested recommendations for deploying the Triconex 3636R.

External Power Supply Sizing

The 3636R acts as a switch; it does not generate power.

Field Tip: You must provide an external power supply for the load side of the relays. When sizing this power supply, calculate the inrush current of all solenoids that might activate simultaneously during an emergency shutdown (ESD). A common mistake is sizing the PSU only for the holding current, leading to voltage sag and failure to trip valves during a critical event.

Inductive Load Protection (Flyback Diodes)

Relays switching DC loads (solenoids) are susceptible to voltage spikes caused by inductive kickback.

Field Tip: Ensure your field devices or interposing relays have built-in flyback diodes or snubber circuits. If the field devices do not have suppression, you must install external suppression modules across the relay terminals. Without this, the voltage spike can damage the relay contacts or cause electromagnetic interference (EMI) that resets the processor.

“Simplified” vs. TMR Logic

The 3636R is a “Simplified” (Non-TMR) module.

Field Tip: This module does not have internal Triple Modular Redundancy (TMR). To achieve SIL 3 compliance, you must use external voting. For example, if you are tripping a critical valve, you should wire three separate 3636R channels (from three different modules) in a 2oo3 (Two-out-of-Three) configuration. Do not rely on a single 3636R channel for a final safety element unless your Safety Requirement Specification (SRS) explicitly allows it (e.g., for low-demand alarms).

Buyer’s Guide & FAQ

What is the difference between the 3636R and the 3635R?

The primary difference lies in the relay state and logic.

Selection Advice: The 3636R is typically configured for Normally Closed (NC) logic in its de-energized trip state (or strictly “Simplified” non-TMR), whereas the 3635R is often associated with Normally Open (NO) or different TMR configurations. Always check the specific “Trip Logic” (Energize-to-Trip vs. De-energize-to-Trip) required by your safety philosophy before purchasing.

Can I replace a 3601E with a 3636R?

Yes, but with wiring modifications.

Selection Advice: The 3601E is a 16-channel TMR module. The 3636R is a 32-channel Simplified module. While the 3636R fits in the same chassis, you cannot simply swap them 1-for-1. You will likely need to reconfigure your logic to account for the loss of internal TMR and re-wire the terminal panels to accommodate the different pinout and higher density of the 3636R.

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