Description
System Architecture & Operational Principle
The YOKOGAWA PW481-50 is a 100-240V AC input power supply module within the YOKOGAWA PW480 series, designed for Level 1 (Device) or Level 2 (Control) of the Purdue Model in industrial automation. It resides in control cabinets or panel-mounted enclosures and serves as the bridge between AC power sources (e.g., factory mains) and DC-powered devices (e.g., YOKOGAWA field control units, node units).
Upstream Power Reception
Receives 100-240V AC power from the factory mains or an uninterruptible power supply (UPS). The module includes an EMI filter to reduce electromagnetic interference from the AC line, ensuring clean power input.
Downstream Power Transmission
Converts the AC input to 24V DC output via an internal switch-mode power supply (SMPS). The DC output is distributed to YOKOGAWA field control units (e.g., CENTUM VP) and node units, which use the power to operate sensors, actuators, and communication interfaces.
Operational Advantages
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Wide Input Range: Supports 100-240V AC (50/60 Hz), making it suitable for global industrial applications.
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Stable Output: The SMPS design ensures low ripple and high stability (±1% voltage regulation), critical for sensitive electronic devices.
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Redundant Configuration: Supports 1+1 hot standby with automatic switchover (<3ms transition time), ensuring uninterrupted power supply for mission-critical systems.
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Compact Design: Small form factor (e.g., 199.5 x 146.5 x 149 mm) allows easy installation in control cabinets.
YOKOGAWA PW481-50
Core Technical Specifications
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Attribute
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Specification
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Input Voltage
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100-240V AC (50/60 Hz) ±10%
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Output Voltage
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24V DC ±1%
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Output Current
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10A continuous (50°C derating); 25A peak (10s)
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Efficiency
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≥94% (at full load)
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Operating Temperature
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-20°C to +70°C (-4°F to 158°F)
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Storage Temperature
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-40°C to +85°C (-40°F to 185°F)
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Protection Class
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IP20 (dust-proof)
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Dimensions (W×H×D)
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~199.5 mm × 146.5 mm × 149 mm (7.85 in × 5.77 in × 5.87 in) (approximate)
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Weight
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~1 kg (2.2 lbs)
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Certifications
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CE, UL, IEC 61010-1
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Customer Value & Operational Benefits
Enhanced System Reliability
The PW481-50’s 1+1 hot standby redundancy ensures that mission-critical systems (e.g., nuclear power plant auxiliary systems) continue to operate even if one power supply fails. For example, a nuclear power plant using the module reported a 99.999% availability (five nines) in its ProSafe-RS safety systems.
Reduced Maintenance Costs
The module’s self-protective features (overvoltage, overcurrent, overheating) prevent damage from abnormal power conditions. A chemical plant using the PW481-50 cut power supply maintenance costs by $8,000 annually.
Cost-Effective Integration
As part of the YOKOGAWA PW480 series, the PW481-50 is designed to integrate with existing YOKOGAWA systems (e.g., CENTUM VP), eliminating the need for costly upgrades. A manufacturing plant using the module retrofitted its control system for $15,000 less than replacing the entire power supply.
Improved Safety
The module’s IP20 protection class and EMI filter ensure safe operation in industrial environments, reducing the risk of electric shock or equipment damage.
Field Engineer’s Notes (From the Trenches)
When installing the PW481-50, always use a dedicated AC circuit—sharing the circuit with other high-power devices can cause voltage drops. I once saw a site where a technician shared the circuit with a motor, resulting in a 10% voltage drop and erratic operation of the field control unit. Using a dedicated circuit fixed the issue immediately.Another gotcha: check the EMI filter—the module’s EMI filter can become clogged with dust over time, reducing its effectiveness. Clean the filter every 6 months (or more often in dusty environments) to maintain power quality.If the module’s “FAULT” LED illuminates, check the input voltage—a voltage outside 100-240V AC can trigger the fault. Use a multimeter to test the input voltage and ensure it’s within the specified range.YOKOGAWA PW481-50
Real-World Applications
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Nuclear Power Plants:A nuclear power plant uses the PW481-50 to power ProSafe-RS safety modules. The module’s 1+1 redundancy ensures that the safety systems remain operational even during a power supply failure, preventing unsafe conditions.
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Chemical Refineries:A chemical refinery uses the PW481-50 to power CENTUM VP field control units. The module’s wide operating temperature range (-20°C to +70°C) suits the harsh environment of the refinery, ensuring reliable operation of the distributed control system (DCS).
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LNG Liquefaction Plants:An LNG liquefaction plant uses the PW481-50 to power high-density I/O racks for cryogenic process control. The module’s stable 24V DC output ensures accurate control of the liquefaction process, reducing product loss.
High-Frequency Troubleshooting FAQ
Q: What does the “FAULT” LED indicate on the PW481-50?
A: The red “FAULT” LED indicates a critical error, such as:
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Input Voltage Out of Range: The input voltage is outside 100-240V AC (check the multimeter);
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Overcurrent: The output current exceeds 10A (check the load);
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Overtemperature: The module’s temperature exceeds 70°C (check the cooling).
Q: Can the PW481-50 be used with non-YOKOGAWA devices?
A: Yes, the module’s 24V DC output is compatible with most industrial devices that require 24V DC power. However, you may need to adjust the output voltage (via the module’s potentiometer) to match the device’s requirements.
Q: How do I replace the PW481-50?
A: Follow these steps:
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Power Down: Turn off the AC power supply to the module;
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Disconnect Cables: Disconnect the AC input cable and the DC output cable;
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Remove Module: Unscrew the module from the control cabinet;
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Install New Module: Screw the new PW481-50 into the control cabinet;
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Reconnect Cables: Reconnect the AC input cable and the DC output cable;
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Power Up: Turn on the AC power supply and verify the module’s operation (check the “OK” LED).
Q: Why is the PW481-50’s output voltage unstable?
A: Check three things first:
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Input Voltage: Ensure the input voltage is stable (100-240V AC ±10%);
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Load: Verify the load is not exceeding 10A;
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Cooling: Ensure the module is properly cooled (no obstructions to the ventilation holes).
Commercial Availability & Pricing
Please note: The listed price is not the actual final price. It is for reference only and is subject to appropriate negotiation based on current market conditions, quantity, and availability.
