Understanding the 1746-P1 Power Supply in Industrial Automation
In modern manufacturing environments, reliable power delivery is critical for programmable logic controllers (PLCs) to maintain uptime and process integrity. The Allen-Bradley 1746-P1 is a SLC 500 power supply designed to provide stable backplane power to modules within a 1746 chassis. This component ensures that attached I/O and processor modules receive consistent voltage, supporting continuous operation in demanding industrial settings.
Key Technical Specifications of the 1746-P1
The 1746-P1 operates with a nominal input voltage of 120/220 Volts AC and accepts a frequency range of 47 to 63 Hertz. It delivers an internal current capacity of 2 Amps at 5 Volts DC and 0.46 Amps at 24 Volts DC, with an output voltage range of 18 to 30 Volts DC. The power supply has an input power rating of 42 Watts and an inrush current of 20 Amps, ensuring robust startup performance.
Physical dimensions are 5.5 x 2.3 x 5.7 inches, and the unit weighs 2 pounds (0.9 kilograms). The operating temperature range is 0 to 60 degrees Celsius, with current capacity derated by 5% when temperature exceeds 55 degrees Celsius. Fuse protection is provided via a 1746-F1 or equivalent fuse, safeguarding against short-circuit hazards.
Application Scenarios and Use Cases
The 1746-P1 is commonly deployed in SLC 500 control systems for applications such as conveyor line management, packaging machinery, and material handling. In a typical setup, it powers a chassis containing analog input modules, digital output modules, and a processor, enabling coordinated automation tasks. Its ability to supply both 5VDC and 24VDC backplane currents makes it suitable for mixed-module configurations.
For example, in a batch processing plant, the 1746-P1 can support a rack with temperature control modules and discrete I/O, ensuring stable operation even during voltage fluctuations. The CPU hold-up time of 20 ms at full load and 3000 ms at no load allows the controller to maintain program scanning briefly during power dips, enhancing system resilience.
Compatibility and Integration with SLC 500 Systems
The 1746-P1 is designed exclusively for use with 1746 chassis, which house SLC 500 controllers and I/O modules. It installs at the leftmost slot of the chassis, whether in a main, expansion, or remote I/O rack. Only one power supply is required per chassis, simplifying system design. The input jumper must be set before applying power to avoid hazardous voltage exposure on exposed pins.
For user-power overcurrent conditions, the behavior varies by manufacturing origin: Series A units made in Japan undergo a power supply shutdown and CPU fault, requiring a user program reload for recovery. Units made in Malaysia experience a 24VDC user shutdown while the CPU continues, with recovery achieved by correcting the overcurrent condition. Undervoltage scenarios allow the power supply to continue operating controllers briefly, with operations resuming once normal input voltage is restored.
Comparison with Similar Power Supply Modules
When evaluating power supplies for SLC 500 systems, the 1746-P1 can be compared to other models in the same series. Below is a comparison based on available specifications:
| Parameter | 1746-P1 | 1746-P2 (typical) |
|---|---|---|
| Input Voltage | 120 to 220 VAC | 120/220 VAC |
| Internal Current (5VDC) | 2 A | 5 A |
| Internal Current (24VDC) | 0.46 A | 0.86 A |
| Input Power | 42 Watts | 90 Watts |
| Weight | 2 lb (0.9 kg) | 3 lb (1.36 kg) |
Note: The 1746-P2 data is provided for reference only; always verify specifications from official documentation. The 1746-P1 offers a compact, lower-power option suitable for smaller chassis configurations.
Frequently Asked Questions About the 1746-P1
What is the input voltage range for the 1746-P1 power supply?
The 1746-P1 has a nominal input voltage of 120/220 Volts AC, with a line voltage requirement of 85 to 132 Volts or 170 to 265 Volts AC, at a frequency of 47 to 63 Hertz.
What is the CPU hold-up time for the 1746-P1?
The CPU hold-up time is 20 milliseconds at full load and 3000 milliseconds at no load, allowing the controller to continue scanning briefly during power interruptions.
How does the 1746-P1 handle overcurrent conditions?
The power supply includes fuse protection via a 1746-F1 or equivalent. For user-power overcurrent, Series A units made in Japan cause a power supply shutdown and CPU fault, while units made in Malaysia result in a 24VDC user shutdown with CPU continuation.
What is the operating temperature range for the 1746-P1?
The operating temperature range is 0 to 60 degrees Celsius. Current capacity is derated by 5% when the temperature exceeds 55 degrees Celsius.
Conclusion
The Allen-Bradley 1746-P1 remains a dependable power supply solution for SLC 500 systems, offering essential backplane power with built-in protection features. Its compatibility with 1746 chassis and support for both 5VDC and 24VDC currents make it a versatile choice for various industrial automation applications. Please verify current lifecycle status and availability with Petro Auto Tech before ordering.
