Description
PSMU-350-3 — Technical Overview
Product: PSMU-350-3, DIN-Rail Mountable Switching Power Supply
Manufacturer: Various (common configuration from manufacturers like Siemens, Mean Well, Phoenix Contact, etc.)
Primary Application: A compact, high-efficiency DIN-rail mountable AC/DC switching power supply designed to provide reliable, regulated 24V DC power for industrial automation systems, PLCs, sensors, relays, and other control circuitry.
1. Key Features & Functions
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Wide 3-Phase Input Range: Typically accepts 340-550V AC, 3-phase + Neutral (or a similar wide range), making it suitable for global industrial voltage standards without manual tapping.
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Regulated 24V DC Output: Provides a single, well-regulated 24V DC output at up to ~14.6A (350W / 24V ≈ 14.6A).
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High Efficiency: Modern switching designs offer high efficiency (>90%), reducing heat generation and energy costs.
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Active Power Factor Correction (PFC): Standard on units of this class to meet harmonic current emission standards (e.g., IEC 61000-3-2) and improve utilization of the supply network.
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Robust Protection:
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Output: Overload, overvoltage, and short-circuit protection.
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Input: Surge and overvoltage protection.
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Status Indication: LEDs for power (AC input present) and output status (DC OK).
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Cooling: Typically convection-cooled (fanless) for reliability, relying on a metal housing and heatsink design.
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Mounting: Standard DIN-rail (TS35/7.5 or 15) mounting for easy installation in control panels.

2. Common Technical Specifications (Generalized)
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Input Voltage: 3 AC 340-550V (or 380-480V), 45-65 Hz.
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Output:
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Voltage: 24 V DC (adjustable within a small range, e.g., 24-28V).
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Current: 14.6 A continuous at 40°C.
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Power: 350 W continuous.
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Efficiency: Typically >92%.
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Power Factor (PF): >0.95 (with active PFC).
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Protection Class: IP20 (for mounting inside an enclosure).
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Operating Temperature: 0 to +60°C (or +70°C) with derating above 40-50°C.
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Safety & EMC Standards: Compliant with UL 508, IEC/EN 62368-1, IEC/EN 61000-6-2, IEC/EN 61000-6-4.
3. System Integration & Design Considerations
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Upstream Protection: Requires appropriately rated 3-phase circuit breaker or fuse on the input side.
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Downstream Distribution: The 24V DC output is typically connected to a DC distribution block or a fuse/terminal block assembly to branch power to various loads (PLCs, I/O cards, sensors, actuators).
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Parallel Operation: Some models support redundant or current-sharing parallel operation using a dedicated interface cable to increase system availability or total current capacity.
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Derating: Always check the derating curve in the manual. Output current capacity decreases as ambient temperature increases. At 60°C, it may only deliver 60-70% of its rated current.
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Load Calculation: Ensure the total connected load (including inrush currents of solenoids and contactors) does not exceed the power supply’s rated capacity, accounting for derating.
4. Typical Applications
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Industrial Control Panels: Primary power source for PLC systems, motor starters, HMI panels, and network equipment.
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Factory Automation Lines: Powering distributed I/O stations, robotic controllers, and vision systems.
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Process Control Systems: Supplying power to valve positioners, transmitters, and process controllers.
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Packaging & Material Handling Machinery.

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