Honeywell 05701-A-0325 DC Input Card, Main 24 VDC Power Interface for System 57 Gas Detection Racks

Brand Honeywell

Model Honeywell 05701-A-0325

Product Overview

The Honeywell 05701-A-0325 is the DC Input Card of the Honeywell Analytics System 57 family, the modular gas detection and fire-and-gas control platform originally developed by Sieger and Zellweger Analytics. While the channel cards in a System 57 rack get most of the attention because they read the detectors, none of them can function without a clean, protected supply, and that is precisely the job of the Honeywell 05701-A-0325. It is the single electrical entry point through which external 24 V DC power enters the sub-rack.

From its terminals, the Honeywell 05701-A-0325 routes the incoming supply through the Engineering Card and onward to the sub-rack backplane, where it becomes the common power rail for every control card, relay card and interface card fitted in the assembly. This centralised distribution is what allows a rack holding up to sixteen gas detection channels in a 19-inch sub-rack to be energised from one managed source rather than a forest of individual feeds.

What elevates the Honeywell 05701-A-0325 above a simple terminal block is its protection and redundancy design. The card carries an onboard fuse on the main DC distribution path, a hardware-level reverse polarity protection circuit that shields backplane electronics from wiring mistakes, and low-pass RFI filtering that attenuates high-frequency interference arriving along the power cable. It also provides a separate auxiliary DC input, diode-isolated from the primary feed, so a standby battery bank can be connected in parallel with the main PSU and take over seamlessly if the primary supply fails. For a gas detection system whose entire purpose is to stay alive when everything else does not, that continuity is the whole point.

Request Price

Description

Technical Specifications

Parameter Name	Parameter Value
Product Model	Honeywell 05701-A-0325
Manufacturer	Honeywell Analytics (Sieger / Zellweger Analytics heritage)
Product Type	DC Input Card, sub-rack power input and distribution module
System Platform	Honeywell System 57 / Sieger 5701 Gas Detection Control System
Primary Function	Main DC power entry point for the sub-rack; distributes supply via the Engineering Card and backplane to all fitted cards
Nominal Input Voltage	24 V DC external supply
Input Voltage Range	18 to 30 V DC
Output Voltage	24 V DC distributed to the rack backplane
Maximum Output Current	5 A
Auxiliary Input	Auxiliary DC input for standby backup battery, diode-isolated from the primary supply
Isolation Method	Dual-diode isolation between PSU input path and AUX (battery) input path
Protection Features	Onboard fuse on the main DC distribution trace, reverse polarity protection, RFI (radio frequency interference) low-pass filtering
Field Termination	Two-part removable terminal block TB1, allowing card removal without disconnecting individual wires
TB1 Connections	PSU (+), PSU (-), AUX (+), AUX (-), GND instrumentation clean earth shield
Card Format	Standard 3U plug-in card for 19-inch and half 19-inch System 57 sub-racks
Installation Note	In racks with more than eight 5704 catalytic control cards, control cards are powered via their Quad Relay Interface Cards and this card feeds the main Engineering Card
Operating Temperature	0°C to +55°C typical industrial safety environment rating
Approximate Dimensions	100 mm x 160 mm x 25 mm card assembly
Approximate Weight	0.15 kg to 0.3 kg for the card; approximately 2 kg as shipped with packaging
Certifications	CE, with system-level UL, TUV and CSA compliance on System 57 assemblies
Country of Origin	United States / United Kingdom depending on production batch
Product Lifecycle Status	Legacy and discontinued; supplied as new surplus, tested used or refurbished spare

Main Features and Advantages

Centralised power distribution for the whole rack: Instead of feeding each gas channel card individually, the Honeywell 05701-A-0325 establishes one managed power entry point and pushes regulated 24 V DC across the backplane to every slot. This simplifies cabinet design, reduces the number of external supply terminations, and gives maintenance teams a single, clearly identified place to measure and troubleshoot rack power.

Protection that defends the safety system from its own environment: Three layers of protection sit on the card. The onboard fuse intercepts overcurrent and short-circuit conditions before they can propagate into the backplane; the reverse polarity circuit prevents a mis-wired supply from destroying connected electronics; and the RFI filtering stage attenuates the high-frequency noise that variable-speed drives, radio equipment and switching power supplies inject into plant DC networks. In a gas detection rack, where a nuisance fault can trigger a spurious alarm or mask a real one, this filtering is functional rather than cosmetic.

Redundant power paths for continuous safety coverage: The Honeywell 05701-A-0325 accepts a primary PSU feed and an auxiliary standby battery feed simultaneously, with diode isolation keeping the two sources electrically separate so neither back-feeds the other. Should the main supply fail during an incident, the gas detection system keeps monitoring, which is exactly when operators most need it. This capability is why the card is specified in high-integrity control rooms and on offshore installations where the fire and gas system must outlast a power disturbance.

Serviceability designed around uptime: The two-part removable terminal block TB1 means the card can be withdrawn and replaced without disturbing a single field wire, an important consideration in a live gas detection cabinet where re-terminating power under time pressure invites errors. Combined with the card’s simple, passive construction, this makes the Honeywell 05701-A-0325 one of the most straightforward modules in the System 57 rack to swap during an outage.

Native compatibility with the System 57 ecosystem: As a purpose-built card rather than a generic power module, the Honeywell 05701-A-0325 matches the 3U form factor, backplane pinout and power routing philosophy of the System 57 and Sieger 5701 platform. It works in concert with the Engineering Card that distributes power and manages backplane communication, so the rack behaves as one engineered system instead of a collection of modules.