Introduction
When a single power supply unit (PSU) isn't enough to meet your system's demands, you have two primary options: Parallel Connection or Redundant Configuration. While they look similar on paper, their goals and technical requirements differ significantly.
Parallel vs. Redundant: What’s the Difference?
- Parallel Connection: The primary goal is Current Boosting. By linking multiple PSUs, you combine their outputs to support a larger load that a single unit couldn't handle.
- Redundant Configuration: The primary goal is Reliability. In a redundant setup (like 1+1 or N+1), the extra PSU acts as a backup. If one unit fails, the others take over seamlessly.
Crucial Note: Standard parallel PSUs often lack reverse current protection. If one unit fails in a simple parallel setup, it could become a load for the others, potentially crashing the whole system. For true redundancy, always use a PSU with built-in redundancy functions or implement an external Redundancy (ORing) Module.
7 Essential Requirements for Parallel Connections
To ensure stable operation and even current sharing, follow these technical guidelines:
- Unified Control Wiring: Using models like the PSP series, you must connect the P (LP/CS) terminals together. This allows the units to "communicate" and balance the load. Ensure all inputs and outputs are connected in parallel before connecting to the AC source or the load.
- Minimize Voltage Variance: The output voltage difference between units should be as small as possible—typically less than 0.2V. Large differences cause the unit with the higher voltage to shoulder the entire load, leading to premature failure.
- Heavy-Duty Wiring: Use short, large-diameter cables for paralleling. Connect the units to each other first to create a common bus, then run the connection to the load. This minimizes wiring impedance differences.
- The 90% Rule: To account for minor imbalances and heat, the total system load should not exceed 90% of the combined rated power.
- Minimum Load Awareness: If the total load drops below 10% of an individual PSU's rating, monitoring signals (like Power Good, Pok, or Alarm signals) and LED indicators may flicker or malfunction.
- Limit the Scale: To maintain effective current sharing and stability, it is generally recommended to parallel no more than 4 to 6 units at a time.
- Voltage Sensing: In specific models, utilize the +S and -S (Remote Sense) terminals. These help compensate for voltage drops across cables and reduce unstable voltage pulsations.
Application Scenarios
- Parallel Application: High-power industrial machinery, large-scale LED displays, or battery charging stations where the total wattage exceeds 3000W.
- Redundant Application: Servers, telecommunications, and mission-critical medical equipment where "zero downtime" is the priority.
Conclusion
Parallel connections are an excellent way to scale power, provided you pay strict attention to wiring impedance and voltage matching. However, if your goal is system "insurance" rather than just "more power," a dedicated redundant module is a non-negotiable requirement.
If you have any technical issues, feel free to contact our team at contact@wellforces.co.nz. We provide professional support and a wide range of solutions.
