Parallel Power Supplies: A Complete Guide to Increasing Current Capacity and Reliability

Introduction

In many test and industrial applications, a single power supply may not provide enough current to meet system demands. Connecting power supplies in parallel is a practical solution that allows users to increase available current while maintaining a stable voltage. This technique can also improve system redundancy, reducing the risk of downtime due to power failures.

In this guide, we’ll explore the fundamentals of parallel power supply operation, key considerations for successful implementation, and examples of Tektronix power supplies that support parallel configurations.

What Are Parallel Power Supplies?

Parallel power supplies refer to a configuration where multiple DC power supplies are connected in parallel to increase total output current. Each power supply shares the current load, ensuring that no single unit is overloaded.

Key Benefits of Parallel Operation:

• Higher Current Output – Allows for increased power delivery by combining the output of multiple units.
• Redundancy & Reliability – If one power supply fails, others can continue providing power.
• Scalability – Expandable configurations allow for flexible current increases as needed.
• Load Balancing – Distributes electrical stress across multiple power supplies, extending longevity.

How to Connect Power Supplies in Parallel

1. Choose Compatible Power Supplies

   For optimal performance, use power supplies of the same model with identical voltage and current ratings. Differences in internal resistance or response times can cause imbalances, leading to one supply shouldering more current than others.

   While the above is true for many power supplies, EA's 10000 series products allow the user to combine different power levels in parallel. The only requirements are that they must have the same voltage rating, and they must be the same family. Examples are pairing PSB with PSBE or PUB and PSI with PS or PU.

   Recommended Tektronix Power Supplies for Parallel Operation:

   • Keithley 2231A-30-3 – A triple-output DC power supply that can be combined to increase total current.
     
     
   
   • EA-PSI 9000 Series – High-power bidirectional DC supplies capable of parallel configuration.
     
     

2. Use Load Sharing or Current Balancing Features

   Some power supplies include built-in current-sharing capabilities, ensuring that each unit contributes evenly. Tektronix’s Keithley 2260B Series includes automatic master-slave operation, simplifying the parallel setup.

3. Connect Outputs with Proper Wiring

   To wire power supplies in parallel:

   • Connect all positive terminals together.
   • Connect all negative terminals together.
   • Use thick, low-resistance wiring to minimize voltage drops and ensure even current distribution.

4. Enable Current Sharing Mode

   If the power supplies support a master-slave configuration, set one as the master and others as slaves. This mode allows the master supply to control and distribute the current evenly.

5. Monitor and Adjust as Needed

   Use measurement tools like oscilloscopes and digital multimeters to verify voltage stability and current distribution. Tektronix's Keithley DMM6500 provides high-precision measurements to ensure balance.

Applications of Parallel Power Supplies

Parallel operation is widely used in industries requiring high-current solutions, including:

• Battery Charging & Testing – Used in EV battery research and industrial applications.
• Power Electronics Development – Essential for validating high-power semiconductor devices.
• Aerospace & Defense Testing – Ensures robust testing environments for mission-critical electronics.

Conclusion

Using parallel power supplies effectively can help engineers and researchers achieve higher current capacity, system redundancy, and better load distribution. By choosing Tektronix’s, 2231A-30-3, or EA-PSI 9000 Series, users can build scalable and reliable power solutions for demanding applications.