How to Use Overvoltage and Overcurrent Protection?
08 Oct 2025
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In electronic experiments, equipment testing, or circuit maintenance, the overvoltage (OVP) and overcurrent (OCP) protection functions of DC regulated power supplies are the core safeguards for equipment safety and reliable operation. These two functions automatically respond to abnormal voltage or load faults, preventing load burnout, power supply damage, and safety accidents. This article explains the principles, application scenarios, and parameter setting procedures of these two protection functions.
I. Overvoltage Protection (OVP): The "Voltage Safety Valve" for Loads
Overvoltage protection targets abnormal increases in output voltage. When the voltage exceeds the preset upper limit, it immediately cuts off or limits the output to prevent excessive voltage from breaking down capacitors, burning out integrated circuits, and other precision components.
1. Core Role and Application Scenarios
- Core Value: Avoids voltage hazards caused by "incorrect voltage adjustment" or "power supply voltage regulation circuit failure". For example, when powering a microcontroller rated at 5V, if the voltage accidentally rises to 12V, OVP can instantly cut off the output to prevent chip damage.
- Typical Scenarios:
- Capacitor charging: Electrolytic capacitors have a fixed voltage rating (e.g., 16V). Overvoltage can cause leakage or explosion, and OVP limits the maximum voltage.
- Precision testing: Sensors and operational amplifiers are sensitive to voltage; OVP ensures the power supply stays within the safe threshold.
2. Practical Setting Steps and Parameter Recommendations
The OVP value is recommended to be 1.2 times the maximum operating voltage of the load (e.g., 14.4V for a 12V-rated load), balancing safety and false trigger prevention. The steps are as follows:
- Power-off Preparation: Disconnect the power supply from the load, keeping only the power supply connected to the mains.
- Voltage Adjustment: After turning on the power, use the "VOLTAGE" knob to adjust the output voltage to the protection threshold (e.g., 14.4V).
- Protection Point Calibration: Use a flathead screwdriver to adjust the recessed "OVP" potentiometer on the panel until the power supply emits a prompt beep or the output light turns off (protection triggered).
- Reset Verification: Turn off the power, adjust the voltage back to the normal operating value (e.g., 12V), and restart the power supply. The output should resume, indicating successful setting.
II. Overcurrent Protection (OCP): The "Current Barrier" for Power Supplies and Loads
Overcurrent protection monitors the output current. When the current exceeds the set value, it automatically enters current-limiting mode or cuts off the output, preventing current surges caused by load short circuits or incorrect wiring, and protecting the power supply's switching tubes, rectifier bridges, and other components.
1. Core Role and Application Scenarios
- Core Value: Resolves issues such as "load short circuits" and "incorrect current matching". For example, if the positive and negative terminals are accidentally shorted during wiring, OCP can quickly limit the current to prevent overload burnout of internal power supply components.
- Typical Scenarios:
- Circuit debugging: New circuits may have hidden short circuits; OCP triggers during power-on to prevent fault expansion.
- Battery charging: When charging lithium batteries, if the current exceeds the tolerance limit, OCP timely limits the current to avoid battery swelling and fire.
2. Practical Setting Steps and Parameter Recommendations
The OCP value is generally set to 1.2 times the rated current of the load (e.g., 2.4A for a 2A-rated load). The operation is divided into two cases:
- Power Supplies with a "Limit" Key:
- After turning on the power, press and hold the "Limit" key; the ammeter displays the current current-limiting value.
- Turn the "CURRENT" knob to adjust the value to the target protection value (e.g., 2.4A).
- Release the "Limit" key; the ammeter resumes displaying the actual output current, and the setting is complete.
- Basic Power Supplies Without a "Limit" Key:
- Disconnect the load and short-circuit the positive and negative output terminals of the power supply with a wire.
- After turning on the power, adjust the "CURRENT" knob to make the ammeter display the target protection value (e.g., 2.4A).
- Remove the short-circuit wire, turn off the power, and the parameters are saved automatically.
Conclusion
Overvoltage and overcurrent protection are key safety guarantees for DC regulated power supplies. Their settings and use directly affect equipment lifespan and operational safety. Beginners should remember the core principles of "matching parameters to the load, reserving safety margins, and checking status regularly". Give full play to the role of these protection functions in practice to avoid risks and develop standardized operating habits. For special scenarios (e.g., medical or aerospace power supply), it is recommended to select high-end power supplies with hierarchical protection and fault recording functions, and configure parameters accurately according to the manufacturer's manual.
Product Recommend
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