Allen‑Bradley 1797‑PS2N2 FLEX Ex I/O Intrinsically Safe Explosion‑Proof Power Supply Module

Allen‑Bradley 1797‑PS2N2 FLEX Ex I/O intrinsically safe explosion‑proof power supply module is designed for distributed I/O control systems deployed in hazardous areas. 1797‑PS2N2 delivers 24V DC intrinsically‑safe output and integrates four independent intrinsic‑safety limiting channels. Built‑in galvanic isolation eliminates the need for additional intrinsic safety barriers. 1797‑PS2N2 supports removal‑and‑insertion‑under‑power, enabling module replacement and wiring modification without system shutdown within explosion‑hazardous zones. Conformal coating protects the unit against corrosive gas in field environments. It widely interfaces with various digital and analog FLEX Ex I/O modules to provide controlled and safe power supply for Zone 1, Zone 22 and Class I/II/III Div1 hazardous operating conditions. This product has reached end‑of‑life status.

Technical Specifications

Product Series: FLEX Ex I/O (Bulletin 1797) 

Device Type: Fieldbus I/O, intrinsically‑safe explosion‑proof power supply 

Input Supply Voltage: 19‑32V DC 

Per‑channel Output Power: 8.5W, four independent galvanically‑isolated intrinsic‑safety output channels 

Operating Temperature Range: ‑20℃ ~ +70℃ 

Explosion‑Proof Certification Rating: Class I, II, III / Div1, Zone 1, Zone 22 

Protection Process: Full‑module conformal coating 

Mechanical Features: Hot‑swap capable, 1‑inch NPT conduit threaded ports 

Certifications: ATEX, IECEx intrinsic‑safety certification 

Module Lifecycle Status: Discontinued, engineering‑replacement spare part

Core Advantages

Built‑in complete galvanic isolation removes extra intrinsic safety barriers during project deployment. It reduces cabinet‑mount hardware quantity and simplifies on‑site cabling work.

1797‑PS2N2 can be installed close to field explosion‑protected controlled equipment, cutting construction costs for long multi‑core cables, conduits and sealing fittings.

Advanced real‑time diagnostic functions quickly locate faults in power supply loops and individual channels, shortening fault‑troubleshooting time inside hazardous locations.

Hot‑swap hardware architecture allows module replacement while the system remains running, mitigating production downtime losses for chemical explosion‑risk sites.

Dual‑path input feeding supports power supply input redundancy configuration. Four channels feature independent intrinsic‑safety current limiting, so faults on one single channel will not interfere with remaining output loops.

Full‑unit conformal coating extends module service life in humid and corrosive industrial operating sites.

Product Features

Four independent Ex‑rated DC output channels with dedicated energy‑limiting for each channel to guarantee intrinsic‑safe loop performance.

Multiple configuration options are supported to fit FLEX Ex I/O stations with different I/O point densities.

On‑board hardware status LED indicators work together with host‑side diagnostics to retrieve real‑time status including channel overload, undervoltage and communication abnormalities.

No on‑site disassembly‑and‑repair is permitted for the complete unit. Opening the enclosure will invalidate intrinsic‑safety certification credentials. Faulty units shall be fully replaced with spare modules.

Module outputs can only connect to FLEX Ex series intrinsically‑safe I/O modules. Direct connection to ordinary non‑intrinsically‑safe field devices is prohibited.

Equipped with 1‑inch NPT conduit inlet and outlet ports to satisfy installation standards for explosion‑proof conduit wiring.

Application Areas

Explosion‑proof remote I/O stations for petrochemical facilities, explosion‑classified pharmaceutical manufacturing workshops, signal acquisition for oil and gas production sites, instrument power supply for chemical storage tank farms, Zone 22 dust‑explosion hazardous conditions, power feeding for transmitters and NAMUR sensors in hazardous locations, supporting power supply for explosion‑proof valve actuators, distributed intrinsic‑safety fieldbus control systems.

Same‑Brand Product Comparison

Compatible Matching Products

Compatible I/O Modules

1797‑IBN16 (16‑point NAMUR digital input module), 1797‑IE8 (8‑channel analog input module), 1797‑OE8 (8‑channel analog output module), 1797‑IRT8 (8‑channel RTD / thermocouple temperature module), 1797‑OB4D (4‑point digital output module)

Compatible Terminal Bases

1797‑TB3, 1797‑TB3S (FLEX Ex intrinsically‑safe terminal base units)

Compatible Communication Adapter

1797‑ACN15 ControlNet Ex adapter

FAQ High‑Frequency Q&A Section

Q: Can brand‑new 1797‑PS2N2 units still be ordered?

A: This model was officially discontinued on December 31, 2017. No brand‑new mass‑produced stock is available. Purchasers can only source salvaged or surplus spare units. New projects are advised to evaluate alternative engineering replacement solutions.

Q: Can the 1797‑PS2N2 directly replace older 1797‑PS2N for drop‑in installation?

A: Direct replacement is not allowed. Entity parameters have been modified between these two models. System‑wide intrinsic‑safety entity parameters must be re‑validated after replacement, otherwise explosion‑proof safety conditions will be compromised.

Q: Is on‑site disassembly and repair allowed for a faulty 1797‑PS2N2 module?

A: On‑site enclosure opening and repair is strictly forbidden. Dismantling the housing voids ATEX and IECEx intrinsic‑safety certifications. Faulty assemblies require full spare‑unit replacement; component‑level internal repair is prohibited.

Q: How many FLEX Ex I/O modules can one 1797‑PS2N2 unit drive at maximum?

A: Capacity is not determined purely by module quantity. Total power consumption of all connected I/O modules needs to be calculated. Aggregate power across four channels cannot exceed the rated power budget of the power supply. Always validate total load using official power consumption calculation worksheets. Overload will trigger module power dropout and intermittent communication failures.

Q: Can standard 1794‑series regular FLEX I/O modules connect to output channels on the 1797‑PS2N2?

A: This configuration is unsupported. Output loops of 1797‑PS2N2 are energy‑limited intrinsically‑safe circuits intended exclusively for Bulletin 1797 FLEX Ex I/O hardware. Connection of non‑intrinsically‑safe 1794 modules is forbidden.

Q: Can hazardous‑area power wiring and intrinsic‑safety loop cables run inside one shared conduit for 1797‑PS2N2 installation?

A: Shared conduit routing is prohibited. Hazardous‑side power cabling and intrinsic‑safety output cables must maintain physical separation, even inside control enclosures. Follow explosion‑proof wiring specifications from the installation manual.

Q: Will hot‑swap operation of 1797‑PS2N2 damage the FLEX Ex backplane bus?

A: Hot‑swap functionality is built into hardware design. Execute insertion and removal with smooth steady motion to avoid bent base pins. Bent pins on the terminal base may take the entire I/O station offline.

Q: 1797‑PS2N2 shows zero output and all indicator LEDs are off. Which items should be checked first?

A: First verify stable 19‑32V DC input power. Inspect conduit sealing and protective grounding connections. Next confirm total downstream I/O load stays within rated power budget. Excessive load activates protective shutdown and cuts off power output.

Same‑Brand Series Product Models

1797‑IBN16, FLEX Ex 16‑Point NAMUR Input Module 

1797‑IE8, FLEX Ex 8‑Point Analog Input Module 

1797‑IE8H, FLEX Ex 8‑Point HART Analog Input Module 

1797‑OE8, FLEX Ex 8‑Point Analog Output Module 

1797‑OE8H, FLEX Ex 8‑Point HART Analog Output Module 

1797‑IRT8, FLEX Ex 8‑Point RTD / Thermocouple Module 

1797‑OB4D, FLEX Ex 4‑Point Digital Output Module 

1797‑IJ2, FLEX Ex Frequency Counter Input Module 

1797‑TB3, FLEX Ex Intrinsically‑Safe Terminal Base 

1797‑TB3S, FLEX Ex Safety‑Enhanced Terminal Base 

1797‑ACN15, FLEX Ex ControlNet Communication Adapter 

1797‑PS1N, FLEX Ex AC‑Input Intrinsically‑Safe Power Supply 

1797‑PS2E2, FLEX Ex DC‑Input Intrinsically‑Safe Power Supply