Honeywell 05701-A-0328 Triple DPCO Relay Card

The Honeywell 05701-A-0328, also cataloged as the 05701-A-0328 Relay Card, operates as a dedicated hardware component for discrete contact output execution within System 57 (SYS57) control networks. The add-on circuit board functions as an electromechanical switching matrix, translating logic commands from adjacent control modules into distinct physical relay state changes to drive remote annunciation panels, trip circuits, or field interlocks.

Hardware Specifications

Process Control and DCS Instrumentation

• Triple DPCO Contact Matrix and Channel-to-Channel Isolation: The relay board features three independent Double Pole Change Over (DPCO) electromechanical relay channels. Each circuit path is designed with strict galvanic channel-to-channel isolation parameters, completely separating the individual field contact lines from each other and from the low-voltage internal rack logic buses to block external transient inductive feedback loops.
• Fail-Safe Logic Configuration and Loop Integrity: The physical change-over contact structure allows field technicians to hardwire loops into either Normally Open (NO) or Normally Closed (NC) configurations. This versatility ensures proper alignment with fail-safe state execution metrics, allowing the control system to automatically drop or close loops to a designated safe position during an upstream backplane power loss or fault trip.

Frequently Asked Questions

Q: What are the main advantages of a DPCO relay configuration over a standard SPCO relay?

A: A Double Pole Change Over (DPCO) relay controls two completely independent electrical circuits simultaneously from a single internal coil command. This permits a single System 57 channel to switch a field safety actuator line while concurrently routing an isolated secondary signal to a local DCS auxiliary alarm panel or data acquisition register.

Q: Can the 05701-A-0328 relay card be hot-swapped while the sub-rack is running?

A: No. Unplugging the relay board while the system is live will instantly open active loops wired through the DPCO contacts, which could trip connected interlocking systems. The associated channel loop power must be safely bypassed or the sub-rack isolated before executing mechanical module replacement.

Field Installation Guidelines

• Chassis Layout Alignment, Clearance Constraints, and Mechanical Seating: Line up the 0.51 lbs relay board with the designated plastic slot guide tracks inside the System 57 sub-rack. Slide the card straight backward until the rear connector pins engage square with the backplane socket array. Apply steady pressure to seat the card fully, and verify that the front panel fastening tabs are securely locked to resist industrial plant vibration.
• Conductor Separation, Wireway Constraints, and Shield Grounding: Route all heavy AC or DC relay load wires inside enclosed panel conduits completely separated from low-voltage analog sensor lines or digital network buses to eliminate inductive noise cross-talk. Ground the sub-rack frame directly to the control panel central copper earth bar using heavy low-resistance ground straps to safeguard the internal logic core against stray switching currents.