Application Scenarios:
Picture a mid-size municipal wastewater treatment plant running an aeration, digester and disinfection process train: hydrogen sulfide and chlorine off-gassing from the headworks and contact tanks infiltrate the control room, and the integrator has already lost two generations of standard I/O chassis to copper-trace corrosion within three years of commissioning. The engineering pain points are painfully familiar — intermittent backplane faults that appear only during humid weather, connector contact resistance creeping up over months, unplanned controller reboots traced to corroded backplane pins, and a maintenance budget that keeps growing with every spare-chassis changeout. The 1756-A7K was engineered precisely for this class of environment: the conformal coating isolates the backplane traces and connector seats from the corrosive atmosphere, while the robust 1756 platform carries the same controller, I/O and communication module ecosystem as the standard chassis — so the protection upgrade happens at the rack level without disrupting the existing ControlLogix design.rockwellautomation.com+1
Because the 1756-A7K preserves the standard 7-slot footprint, backplane current ratings and mounting envelope of the 1756-A7, migration from a corroded standard chassis is essentially a slot-for-slot replacement: controllers, power supplies, EtherNet/IP bridges and I/O cards lift out and drop in without re-engineering the panel layout or re-wiring the I/O harness. That is the value proposition that keeps the 1756-A7K on the engineering standard list of OEMs and EPCs specifying ControlLogix for corrosive-gas duty worldwide.com.ua+1
Parameter:
| Main Parameters | Value / Description |
|---|---|
| Product Model | 1756-A7K (Bulletin 1756, ControlLogix) |
| Manufacturer | Allen-Bradley – Rockwell Automation |
| Product Category | 7-slot conformally coated ControlLogix chassis (back-panel mounting rack) |
| Number of Slots | 7 (any ControlLogix / GuardLogix module may occupy any slot) |
| Backplane Current, Chassis Max @ 1.2 V DC | 1.5 A |
| Backplane Current, Chassis / Slot Max @ 3.3 V DC | 4 A / 4 A |
| Backplane Current, Chassis / Slot Max @ 5.1 V DC | 15 A / 6 A |
| Backplane Current, Chassis / Slot Max @ 24 V DC | 2.8 A / 2.8 A |
| Power Dissipation (Chassis) | 4.5 W max |
| Coating | Conformal coated for ISA G3 corrosive-gas environments |
| Dimensions (W × H × D) | 367.6 × 158 × 145 mm (14.5 × 6.2 × 5.7 in) |
| Weight | ~1.10 kg (2.4 lb) |
| Minimum Enclosure Size (H × W × D) | 50.8 × 60.9 × 20.3 cm (20 × 24 × 8 in) |
| Mounting | Horizontal only, back-panel; open-style enclosure |
| Operating / Storage Temperature | 0–60 °C (32–140 °F) / −40 to +85 °C (−40 to 185 °F) |
| Relative Humidity | 5–95% noncondensing |
| Vibration / Shock | 2 g @ 10–500 Hz (operating); 30 g operating, 50 g non-operating |
| Grounding | Functional earth 8.3 mm² (8 AWG); protective earth 2.1 mm² (14 AWG) |
| Certifications | c-UL-us (UL File E65584; Class I Div 2 Groups A,B,C,D File E194810); CSA (LR54689C, LR69960C); FM Class I Div 2; CE (EMC 2004/108/EC, EN 61326-1, EN 61000-6-2/-4, EN 61131-2); C-Tick; ATEX II 3 G Ex nA IIC T6 Gc X; KC |
| Temperature Codes | T5 (North America), T6 (IEC) |
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