Description
The Honeywell 05704-A-0145 is a specialized expansion module designed for the System 57 gas detection platform. It provides dedicated relay outputs for the 05704-A-0144 Quad Control Card, enabling the system to trigger localized physical alarms, ventilation fans, or external safety interlocks based on gas concentration levels. While the main control card handles signal processing, the 05704-A-0145 provides the physical switching capacity required for industrial safety executive actions.
Commercial and Availability Status
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Condition: New Original (Factory Sealed)
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Warranty: 12-Month Mechanical and Electrical Warranty
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Availability: In Stock
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Lead Time: Ships within 1 to 2 business days
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Pricing Note: Price varies based on regional inventory levels. Contact our procurement office for a definitive, time-bound quotation.
Technical Specifications
| Parameter | Specification / Value |
| Model Number | 05704-A-0145 |
| Compatibility | Exclusively for use with 05704-A-0144 Quad Control Cards |
| Relay Channels | 16 Relays total (4 Relays per gas channel) |
| Relay Configuration | Single Pole Double Throw (SPDT / Form C) |
| Contact Rating (AC) | 5 A at 250 V AC (Resistive) |
| Contact Rating (DC) | 5 A at 30 V DC (Resistive) |
| Default Logic | De-energized (Configurable for Normally Energized) |
| Output Functions | Alarm 1, Alarm 2, Alarm 3, and Fault per channel |
| Mounting | Attaches to the rear of the Quad Control Card |
| Connection Type | Screw Terminal Blocks |
Functional Architecture
The 05704-A-0145 Relay Card acts as a physical extension of the Quad Control Card. It translates the digital alarm states of the four gas monitoring channels into 16 independent sets of dry contacts.
Mapping Logic
Each of the four gas channels on the companion control card is allocated four relays on this module:
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AL1 (Alarm 1): Typically used for low-level alerts or triggering auxiliary ventilation.
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AL2 (Alarm 2): Usually reserved for high-level alerts and localized beacons/sounders.
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AL3 (Alarm 3): Used for critical executive actions, such as plant-wide shutdown or gas main isolation.
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FLT (Fault): Signals a hardware malfunction, sensor failure, or cable snap for that specific channel.
Contact Flexibility
Every relay provides Normally Open (NO), Normally Closed (NC), and Common (C) terminals. This allows engineers to design fail-safe loops; for instance, wiring a circuit through the NC contacts of a “Normally Energized” relay ensures a trip occurs if the System 57 rack loses total power.
Engineering and Installation Guidelines
1. Hardware Integration
The 05704-A-0145 is a “piggyback” style module. It plugs directly into the rear interface of the 05704-A-0144 Quad Control Card within the System 57 rack. Ensure the locking pins are fully engaged to prevent intermittent contact faults caused by cabinet vibration.
2. Inductive Load Management
While the contacts are rated for 5 A resistive loads, switching inductive loads (such as heavy-duty motor starters or large solenoid valves) can cause significant arcing, leading to contact welding or EMI-related resets of the control card.
Expert Field Note: Always install external suppression (MOV for AC or Flyback Diode for DC) when the 05704-A-0145 is driving an inductive load. For high-current applications, use the card’s relay to drive a larger interposing industrial relay rather than wiring the load directly to the System 57 backplane.
3. Configuration via Control Card
The behavior of the relays (e.g., Latching vs. Non-Latching, Energized vs. De-energized) is defined in the configuration of the 05704-A-0144 Control Card. The relay card itself has no onboard firmware; it simply executes the commands passed from the master control module.
Frequently Asked Questions
Can I use the 05704-A-0145 with the 05701 single-channel cards?
No. The 05704-A-0145 is specifically keyed and wired for the Quad Channel (4-channel) architecture. Single-channel modules use the 05701-A-0301 (Non-Relay) or 05701-A-0302 (Relay) interface modules, which have a different pin-out and form factor.
What happens to the relays if the Control Card is removed?
If the 05704-A-0144 Control Card is unplugged from the rack, the associated 05704-A-0145 Relay Card will lose its drive signal. Depending on how you have wired the contacts (NO/NC) and the configured fail-safe state, this will typically result in a “Fault” state for the connected safety loops.
Is it possible to have “Voting Logic” between channels on this card?
Voting logic (e.g., requiring 2-out-of-4 channels to alarm before a relay trips) is not handled by the relay card hardware. This must be configured in the System 57’s master engineering software or through external hard-wiring of the relay contacts in series/parallel.
| Honeywell 05701-A-0302 Single-Channel Control Card |
| Honeywell 05704-A-0144 System 57 Quad Control Card |
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| Honeywell CC-PWRR01 – Redundant Power Supply Module |
