Configured for redundant power delivery to a PLC-5 I/O chassis, the Allen-Bradley 1771-P4R (1771P4R Power Supply) provides backplane power from an AC input source. The supplied data identifies the unit as a one-slot, 8 A redundant power supply with a 5 VDC output.

Model Identification

The supplied catalog information identifies 1771-P4R as a redundant PLC-5 power supply. The listed variants are 1771-P4R/A, 1771-P4R/B, and 1771-P4R/C. No functional suffix differences are specified in the supplied data, so these revision designations are not assigned additional electrical characteristics.

Electrical and Mechanical Data

PLC-5 Backplane Power Characteristics

The 1771-P4R is specified as a redundant power supply occupying one slot and providing 5 VDC for the associated PLC-5 chassis backplane. The supplied data lists a backplane current of 420 mA.

The input specification identifies 120 VAC at 50/60 Hz, while a separate parameter lists 0-24 VAC as an AC operating voltage. Because the supplied data does not define the relationship between these two values, the 0-24 VAC entry should not be interpreted as the rated input range without confirmation from the applicable Allen-Bradley documentation.

For PLC-5 installations, backplane current loading must remain within the applicable chassis and power-supply limits. Redundant configurations should also be evaluated as a complete power architecture rather than treating the unit as an isolated AC-to-DC converter.

Ordering Information

• 1 x Allen-Bradley 1771-P4R redundant power supply
• 1 x PLC-5 compatible power supply module
• No external redundancy accessory or mounting kit is identified in the supplied data

Installation and Electrical Guidelines

Chassis Installation

• Install the module in a compatible PLC-5 chassis position.
• Confirm the chassis backplane connector is clean before installation.
• Remove power before inserting or removing the module unless the applicable system documentation explicitly permits energized replacement.
• Verify that the module is mechanically seated before applying input power.
• Do not force the module into the chassis connector.

AC Input and Grounding

• Verify the available AC source against the specified 120 VAC, 50/60 Hz input.
• Provide protective grounding and cabinet bonding according to the applicable electrical installation standard.
• Keep AC input conductors separated from low-level signal and communication wiring.
• Route power conductors to minimize unnecessary coupling into I/O and communication circuits.
• Inspect terminal connections for mechanical security before energization.

Backplane Loading

• Calculate the total chassis backplane load before installation.
• The supplied specification identifies 420 mA backplane current for the power supply.
• Do not exceed the applicable chassis power budget.
• Verify redundant supply arrangements using the correct PLC-5 system documentation.
• Do not assume hot-swap operation unless explicitly supported by the applicable hardware documentation.

Frequently Asked Questions

• What PLC family is the 1771-P4R designed for?

  The supplied information identifies the 1771-P4R as a redundant power supply for the Allen-Bradley PLC-5 platform.

• What is the specified AC input?

  The product information specifies 120 VAC at 50/60 Hz. A separate 0-24 VAC value is also supplied but is not sufficiently defined to establish an input range.

• What DC voltage does the unit provide?

  The product information specifies a 5 VDC output for the PLC-5 chassis power system.

• What is the rated current?

  The product description identifies the unit as an 8 A power supply. The supplied data separately lists 420 mA as the backplane current.

• How many slots does the 1771-P4R occupy?

  The supplied product information specifies a one-slot configuration. Physical installation should use a compatible PLC-5 chassis position.

• Is the power supply redundant?

  Yes. The product information explicitly identifies the 1771-P4R as a redundant power supply. Specific redundancy switching behavior is not provided.

• Is hot-swapping supported?

  Hot-swapping is not confirmed by the supplied specifications. Installation or removal should be performed with power removed unless the applicable PLC-5 documentation explicitly permits energized replacement.

• What environmental conditions are specified?

  Operating temperature is 0 deg C to +60 deg C, storage temperature is -40 deg C to +85 deg C, and humidity is 5-95% RH, non-condensing.