HONEYWELL 05701-A-0327 System 57 Relay Card

The HONEYWELL 05701-A-0327, also cataloged as the 05701-A-0327 Double SPCO Relay Card, operates as a dedicated hardware component for relay output switching and fault signaling within Honeywell System 57 control racks. Operating on internal rack power bus supplies, this module accepts control logic triggers from upstream Field Interface Cards and toggles potential-free Single Pole Changeover (SPCO) contacts to drive external annunciators, beacons, emergency shutdown circuits, and auxiliary tripping relays across A1 alarm, A2 alarm, and system fault thresholds.

Hardware Specifications

Channel-to-Channel Isolation & Loop Connectivity

The Honeywell 05701-A-0327 incorporates galvanic channel-to-channel isolation across its voltage-free contact sets to prevent noise coupling into adjacent 4-20 mA HART loop protocol sensing paths. Internal DIP switches allow hardware configuration for normally energized or normally de-energized operation, as well as latching or non-latching alarm states. This physical isolation preserves signal integrity across external control circuits while routing switching logic without ground loop interference.

Frequently Asked Questions

Q: How does the relay card handle normally energized versus normally de-energized configurations?

A: Hardware selectors on the PCB allow technicians to configure individual relays for failsafe (normally energized) operation—where power loss drops the relay into alarm state—or standard (normally de-energized) switching behavior.

Q: What are the maximum switching voltage and current limits for the contact terminals?

A: The potential-free SPCO relay contacts carry a maximum non-inductive load rating of 5 A at 250 VAC or 5 A at 32 VDC per channel.

Q: Can the 05701-A-0327 card be inserted or replaced while the System 57 rack is powered?

A: Rack power must be isolated or the specific slot de-energized before card insertion or removal to prevent electrical arcing across backplane edge connectors and avoid spurious trip execution.

Field Installation Guidelines

Slide the 05701-A-0327 relay card into its assigned System 57 rack slot along the card guides until the backplane connector fully engages. Tighten the front panel securing screws to prevent vibration displacement. Wire external alarm circuits to the rear screw terminal block using 14 AWG to 18 AWG conductors, ensuring stripping lengths do not exceed 6 mm to avoid accidental contact shorting. Ground all external cable shields at the main system earth bar to suppress electro-magnetic induction.