Honeywell Experion PKS FTA-T-20 Digital Output Relay Field Termination Assembly

Product Overview

The FTA-T-20 is a specialized Field Termination Assembly (FTA) within the Honeywell Safety Manager (SMS) and Experion PKS ecosystems. It serves as the physical and electrical interface between the system's digital output modules and the external field equipment.

Designed for high-load or isolated switching requirements, the FTA-T-20 provides 8 channels of relay-contact outputs. Each channel offers NO (Normally Open) and NC (Normally Closed) contacts, allowing for flexible fail-safe configurations. By utilizing interposing relays on the FTA, the system protects the sensitive controller electronics from field-side electrical surges and allows the switching of higher voltages and currents (up to 250 Vac or 110 Vdc) than a standard electronic output could handle.

Technical Configuration

The FTA-T-20 is engineered for seamless integration into Honeywell safety and control racks:

• Channel Density: 8 independent relay channels.

• Contact Type: SPDT (Single Pole Double Throw) configuration, providing both NO and NC terminals for every channel.

• Interface Connection: Connects to the controller I/O module via a standard SIC-C-07 system interconnection cable.

• Field Wiring: Equipped with robust screw terminals for direct connection of field cables, supporting a variety of wire gauges.

• Mounting: Standard DIN-rail mounting for installation in I/O cabinets or marshalling panels.

• NFS (Non-Fail Safe) Design: Typically used in applications where the safety logic is managed by the controller, and the relay acts as the final switching element.

Technical Specifications

Technical FAQs

What is the advantage of using an FTA-T (Screw Terminal) over an FTA-E (ELCO)?

The FTA-T version is designed for direct field wiring where the cables are terminated individually at the assembly. The FTA-E (ELCO) version is typically used for "marshalling-to-marshalling" connections using pre-fabricated multi-core cables. The FTA-T-20 is ideal for cabinets where field sensors/actuators are wired directly to the I/O rack.

Can I mix AC and DC loads on the same FTA-T-20?

While the relay contacts are rated for both 250 Vac and 110 Vdc, it is standard engineering practice to keep load types consistent across an FTA to prevent noise and to simplify maintenance. However, since the 8 channels are galvanically isolated from each other, they can technically switch different voltage sources.

How do I replace a faulty relay on this FTA?

Depending on the specific hardware revision, the relays on the FTA-T-20 are often socket-mounted. This allows for "hot-maintenance" where an individual relay can be replaced without replacing the entire termination assembly or disturbing the wiring of the other 7 channels.

Engineering & Installation Guide

• Wire Termination: Ensure that wire ferrules are used when connecting to the screw terminals. This prevents wire fraying and ensures a gas-tight connection, which is critical in corrosive industrial environments.

• Cable Routing: The SIC-C-07 cable should be routed away from high-power AC lines to prevent induced noise, even though the relay outputs are relatively robust.

• Contact Protection: For highly inductive loads (such as large solenoid valves or motor starters), it is recommended to install external RC snubbers (for AC) or flyback diodes (for DC) to extend the life of the FTA relay contacts.

• Fusing: Always ensure that field-side circuits are properly fused. The FTA-T-20 provides the switching logic, but the current-limiting protection should be handled by external terminal fuses or circuit breakers.