1746-OBP8 8-Channel High-Current Output Module Allen-Bradley

1746-OBP8 8-Channel High-Current Output Module

Product Introduction

The 1746-OBP8 from Allen-Bradley provides eight high-current DC sourcing outputs in a compact SLC 500 form factor. This output module delivers 2A continuous current per point at temperatures up to 60°C, with a total module current of 8A. Operating within a 20.4-26.4V DC range, it directly drives solenoids, horns, pilot lamps, and motorized actuators. Fast turn-off response of just 2ms makes it suitable for precision timing applications. Additionally, front-panel e-fuse LEDs provide clear visual status indication for each output. This module occupies a single slot in SLC 500 fixed or modular chassis and requires an external DC supply for output power.

Key Technical Specifications

The 1746-OBP8 features eight output points arranged in two groups of four points each. Each point delivers 2A continuous current across the full 0-60°C operating range, with a module total of 8A. Surge current capability reaches 4A for 10ms, providing margin for inrush loads. The on-state voltage drop measures a maximum of 1V at 2A, ensuring efficient power delivery. Off-state leakage current stays below 1mA, preventing unintended load activation. Backplane current consumption is only 0.135A at 5V DC, making this output module exceptionally power-efficient.

Signal delay times are notably fast: 1ms for turn-on and 2ms for turn-off under resistive loads. The step response measures 60ms for turn-on and 2.5ms for turn-off. Minimum load current is 1mA, ensuring compatibility with high-impedance devices. Heat dissipation totals 3.08W, with 0.300W per point and a minimum of 0.675W.

Group Configuration and Isolation

The 1746-OBP8 organizes its eight outputs into two electrically isolated groups, each containing four points. This group isolation allows you to power different loads from separate external DC supplies, offering greater flexibility in system design. The isolation voltage between I/O terminals and logic circuitry is rated at 1500V, providing robust protection against electrical faults. Each group shares a common return terminal, simplifying wiring for multiple loads within the same voltage domain.

E-Fuse LEDs and Diagnostics

Front-panel e-fuse LEDs on the 1746-OBP8 provide immediate visual feedback for each output channel. These indicators help you quickly identify which outputs are active or faulted, significantly reducing troubleshooting time. However, please note that this output module does not include electronic protection circuitry. Therefore, external fusing or circuit breakers are strongly recommended for each output to protect against short circuits and overload conditions. Proper external protection ensures reliable operation and extends module lifespan.

Environmental and Mechanical Ratings

Operating temperature for the 1746-OBP8 ranges from 0°C to 60°C, while storage permits -40°C to 85°C. Humidity tolerance spans 5% to 95% non-condensing, accommodating diverse factory environments. Vibration resistance includes 0.015 inch peak displacement at 5-57 Hz and 2.5g acceleration at 57-2000 Hz. Operating shock rating is 30g. This output module holds UL listing, CE compliance, and meets NEMA standard ICS 2-230 for noise immunity. Its open-type enclosure mounts directly into the SLC 500 chassis.

Installation and Configuration

Installing the 1746-OBP8 is straightforward. Slide the module into any available slot within an SLC 500 fixed or modular chassis. The backplane supplies 5V DC power automatically, but you must connect an external 20.4-26.4V DC power supply to generate output power. Field wiring connects via the front-facing terminal block, with each output point clearly labeled. Recommended signal wire size is up to 2 mm² (14 AWG). Configuration occurs through your programming software, where you map the outputs to your control logic. For optimal performance, mount this module away from high-heat sources and ensure adequate airflow.

Driving AC Loads with Interposing Relays

While the 1746-OBP8 provides DC outputs only, you can still control AC loads by using interposing relays. Connect the relay coil to the DC output of this module, and wire the relay contacts to handle the AC voltage circuit. When the module energizes the coil, the relay contacts close or open accordingly. This approach also provides additional isolation between the SLC 500 system and high-voltage AC circuits, enhancing overall system protection. Interposing relays are a cost-effective solution for mixed-voltage control panels.

Typical Applications

This output module excels in high-current DC switching applications. For instance, it directly drives solenoids in hydraulic systems, motorized valve actuators, and clutch/brake controls. It also powers sounding devices such as horns, sirens, and buzzers, plus indicating devices like pilot lamps and alarm annunciator panels. Common industries include automotive manufacturing, packaging machinery, material handling, and conveyor systems. The 1746-OBP8 is compatible with stand-alone, expanded, or remote I/O SLC 500 topologies, offering deployment flexibility across various system architectures.

Packaging List

• 1 x Allen-Bradley 1746-OBP8 output module

• 1 x Removable terminal block (installed)

• 1 x Slot filler label

• 1 x Quick-start guide (printed)

Note: External DC power supply, interposing relays, fuses, and programming software are sold separately.

Shipping Information

All orders ship via FedEx, UPS, or DHL with full tracking and insurance coverage. Expedited shipping options are available upon request. Domestic deliveries typically arrive within 2–3 business days, while international shipments take 5–7 days depending on customs clearance.

Frequently Asked Questions (FAQ)

Q1: Does the 1746-OBP8 include internal short-circuit protection?
No. This output module does not feature electronic protection. You must install external fuses or circuit breakers on each output to safeguard against overloads and short circuits.

Q2: Can I use the 1746-OBP8 with AC loads?
Not directly. This module provides DC sourcing outputs only. However, you can control AC loads by connecting interposing relays between the module outputs and the AC circuits.

Q3: What is the difference between the 1746-OBP8 and the 1746-OB8?
The 1746-OBP8 offers higher current capacity (2A per point vs. 1A), faster turn-off response (2ms vs. 2.5ms), and includes e-fuse LEDs for diagnostics. The OB8 lacks these features and has lower current ratings.

Q4: How do I interpret the e-fuse LEDs on the front panel?
Each output has a corresponding e-fuse LED. When the LED is illuminated, the output is active. If the LED is off, the output is inactive or no external power is present. These LEDs provide real-time visual status for quick troubleshooting.

Q5: What is the maximum wire size I can use with the 1746-OBP8?
The recommended maximum wire size is 2 mm² (14 AWG). Using larger wires may not fit properly in the terminal block and could damage the connectors. Always use copper conductors rated for 60°C or higher.