Description
Product Introduction & Engineering Value
Unreliable or undersized 24 V power is one of the most common causes of intermittent FBM communication faults and unexpected module resets. The FPS400-24 (P0922YU / P0914YZ) is the standard 400 W supply qualified by Foxboro for 200 Series equipment.
It accepts a wide-range input of 85–265 V AC (47–63 Hz) or 108–145 V DC and delivers a tightly regulated 24.0 V DC output at up to 16.7 A. High efficiency, power-factor correction, dual-stage current limiting, and overvoltage protection safeguard both the supply and the connected modules. The unit is convection-cooled (no fans), sealed for G3 environments, and certified for Class I Division 2 / Zone 2 applications. A form-C relay alarm contact reports supply status back to the control system.
Technical Specifications
Output Voltage: 24.0 V DC ±0.2 V (factory set)
Maximum Output Power / Current: 400 W / 16.7 A
Input Voltage Range (P0922YU): 85–265 V AC or 108–145 V DC
Input Frequency: 47–63 Hz
Efficiency: 77 % minimum at 85 V AC; typically 85 % at 120 V AC; typically 92 % at 230 V AC
Inrush Current: 20 A peak at 110 V AC; 40 A peak at 220 V AC (cold start)
Cooling: Convection (fanless)
Protection Features: Dual-stage current limiting, overvoltage shutdown (~28 V), internal fuse
Isolation: 3000 V AC input-to-output; 1500 V AC input-to-chassis; 500 V AC output-to-chassis
Alarm Output: Form-C relay status contact
Environmental / Hazardous Area: ISA Class G3; Class I Div 2 / Zone 2 certified
Mounting: DIN rail (horizontal or vertical), bracket, or wall
Field Application & The “Trench” Experience
A Gulf Coast chemical plant experienced recurring baseplate power dips when a remote FBM cabinet was fully loaded. The existing supply could not maintain 24 V under peak current. An FPS400-24 P0922YU was installed with proper convection clearances. The wide-range input accepted the local 480 V / 277 V-derived 120 V AC feed without additional transformers. After connection to the redundant power bus and verification of the alarm contact, the cabinet ran at full load with stable voltage and no further communication dropouts.
Typical niche applications:
- Primary or redundant 24 V power for standard 200 Series FBM baseplates
- Powering mixed FBM, FCM, and FCP loads in field or remote enclosures
- Installations requiring Div 2 / Zone 2 certification and G3 environmental rating
FPS400-24 P0922YU (P0914YZ)
FPS400-24 P0922YU (P0914YZ)
Transparency SOP: QA & Testing
- Visual inspection of housing, connectors, labeling (P0922YU / P0914YZ), and sealing.
- Power-up across the full input voltage range (AC and DC where applicable).
- Output voltage, regulation, and ripple measurement under light-to-full load.
- Verification of current-limit and overvoltage protection thresholds.
- Form-C alarm contact functional test.
- Elevated-temperature soak at rated load to confirm thermal stability and convection cooling performance.
The Veteran’s Tech Trap Guide
⚠️ Convection clearances are mandatory. The FPS400-24 is fanless. Blocking airflow above or below the unit will force thermal derating or cause shutdown under high ambient temperature or full load.
PRO TIP: When using multiple supplies for redundancy, follow Foxboro parallel or diode-isolation guidelines. Direct paralleling without proper current sharing can produce uneven loading and nuisance trips.
⚠️ Check derating curves. Available output power decreases at lower input voltages and higher ambient temperatures. Do not assume the full 400 W is available under every plant condition.
Dynamic FAQ
Q: What is the difference between P0922YU and P0914YZ? A: P0922YU is the current and most commonly referenced part number for the 120/240 V AC or 125 V DC input version of the FPS400-24. P0914YZ appears in some older documentation or inventory listings as a related or earlier identifier for the same family of power supplies. Always confirm the exact hardware revision when ordering.
Q: What input voltages does the FPS400-24 accept? A: 85–265 V AC (47–63 Hz) or 108–145 V DC.
Q: What is the maximum continuous output? A: 24 V DC at up to 16.7 A (400 W), subject to input voltage and ambient temperature derating.
Q: Is this supply qualified for 200 Series FBMs? A: Yes. The FPS400-24 series is the only power supply family tested and qualified by Foxboro for use with standard 200 Series Fieldbus Modules and baseplates.
Q: Are New Surplus (P0914YZ) units original Foxboro product? A: Yes. Units are original OEM material that have passed full electrical, protection, and thermal testing.
Q: What warranty is provided? A: 12-month warranty against defects in materials and workmanship from the date of shipment for both New Surplus and fully tested refurbished units.
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