The Allen-Bradley 1771-P7, also cataloged as the 1771-P7 Power Supply, operates as a dedicated hardware component for chassis backplane power distribution within Allen-Bradley PLC-5 control systems.
Hardware Specifications
Parameter
Specification
Model
1771-P7
Brand
Allen-Bradley
Origin
USA
Weight
4.25 lbs (1.93 kg)
Dimensions
Stand-Alone Chassis Form Factor
Operating Temp
0 to 60 deg C (32 to 140 deg F)
Power Consumption
108 W (Real Input Power), 176 VA Max (Apparent Power)
Module Type
Stand-Alone AC Power Supply
Nominal Input Voltage
120 VAC / 220 VAC
Input Voltage Range
97-132 VAC / 195-264 VAC
Input Frequency
47 to 63 Hz
Backplane Output Current
16 A @ 5 VDC (5.06 VDC nominal output)
Max Transformer Load
270 VA
Internal Fuse
3 A, 250 V, Normal-Blow
Paralleling Capability
None (Strictly Stand-Alone)
Backplane Bus & Power Isolation Execution
The 1771-P7 converts 120/220 VAC line power into a regulated 5.06 VDC backplane supply, delivering up to 16 A to power 1771 Universal I/O chassis backplanes and PLC-5 processors. Utilizing external D-shell cable interfaces (1771-CP1, 1771-CP2, or 1771-CP3), the supply maintains electrical isolation between line-side AC sources and low-voltage logic circuitry, ensuring stable power delivery across high-density I/O configurations.
Frequently Asked Questions
Q: Can two 1771-P7 power supply units be connected in parallel to increase chassis output current?
A: No, the 1771-P7 is designed strictly as a stand-alone unit. Attempting to connect units in parallel can cause voltage instability, processor memory loss, and system shutdown.
Q: What power cable options connect the 1771-P7 power supply to a 1771 I/O chassis?
A: The supply uses the 1771-CP1 local cable (for mounting on the left side of the chassis) or 1771-CP2 / 1771-CP3 remote cables (5 ft / 5.5 ft max distance).
Field Installation Guidelines
Physical Mounting: Mount the 1771-P7 directly onto the panel on the left side of the 1771 I/O chassis. If mounted as a separate standalone unit, maintain at least 6 inches (152 mm) of vertical clearance for convection airflow.
Jump Setting: Configure the chassis jumper to the "N" position prior to applying power when utilizing an external 1771-P7 power supply.
Power Cable Connection: Connect the D-shell power cable (1771-CP1, 1771-CP2, or 1771-CP3) between the power supply output connector and the chassis backplane power socket. Secure retaining screws.
Line Voltage & Grounding: Wire AC mains supply to the input terminals, ensuring the panel safety ground conductor terminates at the dedicated frame ground stud to mitigate high-frequency EMI.
ESD & Hot-Swap Restrictions: Never connect or disconnect the power supply cable while AC line voltage is applied to avoid arcing and damage to backplane connector pins.
