How to Judge Whether an Over-Voltage and Under-Voltage Protector Needs Replacement?

As the usage time of overvoltage and undervoltage protectors increases, their performance gradually declines, thereby affecting the protection effect on electrical appliances. So how to determine whether the protector needs to be replaced? Below we will introduce several common situations to help you understand the signs that the protector may need to be replaced.

Signals of Declining Protection Performance

1. Frequent Tripping

If the over-voltage and under-voltage protector trips frequently without a clear reason, then attention is needed. Occasional tripping during significant voltage fluctuations is a normal phenomenon, but if it trips frequently under normal voltage conditions, it may be that the internal components of the protector have failed.

2. Physical Damage or Wear

Physical examination is a simple and effective method for judging the health status of protectors. Look for signs such as cracks, discoloration or burning points on the shell. These usually point to overheating or arc discharge inside the equipment.

• Cracks or deformations: Moisture seeps in, damaging the internal circuits
• Discoloration: usually indicates overheating of the component
• Burning point: Indicates excessive current or short circuit
• Corroded terminals: Affect connection quality and performance

3. Abnormal Output Voltage

Using a multimeter to measure the output voltage shows 0 V, or the voltage is extremely low, indicating that the internal detection or drive circuit has failed, and the protector cannot close normally.

4. Extended Reset Delay

The set reset time was 10 s, but the actual reset time exceeded 10s, possibly due to aging of the internal timer component or capacitor leakage.

5. Inability to Reset or Constant Disconnection

After the protector trips, it should be able to reset automatically or manually. If it consistently cannot return to the working state, it indicates that the internal mechanism may be damaged.

6. Age and Service Life Considerations

Most overvoltage and undervoltage protectors have a recommended service life, usually 5 to 10 years, depending on the model and usage conditions. If your protector has approached or exceeded this range, it is recommended to replace it even if it is still working at present. Because after the critical period, the probability of device failure will increase significantly.

Daily Maintenance and Inspection of Over-Voltage and Under-Voltage Protectors

Daily Inspectionl

• Connection Tightness: Check all screws and wire clamping screws for looseness to prevent malfunction or local overheating due to poor contact.
• Casing and Environment: Confirm the casing is free of cracks, moisture, and dust accumulation; maintain ventilation and dryness to prevent corrosion and insulation aging.
• Load Status: Observe whether the connected load is operating normally; if the load is abnormal (such as frequent tripping), further inspection of the protector is needed, as load abnormality is often an early warning signal from the protector.

Weekly Inspection

• Voltage Setting Verification: Use a multimeter or voltmeter to measure the input voltage, confirming it is within the rated range.
• Function Test: Manually or using an adjustable power supply, lower the voltage below the under-voltage threshold and observe whether the protector cuts off the load; then adjust back to normal voltage and confirm whether the protector automatically resets after the set delay.
• Terminal Cleaning: Use a clean soft brush or compressed air to remove dust from the terminals.

Monthly Inspection

• Output Voltage: With the protector in the closed state, use a multimeter to measure the output voltage, requiring the error from the rated voltage to be ≤ 5%. If it exceeds the error range, calibration or replacement is needed.
• Relay Action Time: Use an oscilloscope or timer to record the total time from under-voltage/over-voltage trigger to disconnection, and then to power restoration. Refer to the product technical manual; exceeding the time indicates aging of internal components.
• Contact Resistance: Use a megohmmeter to measure the contact resistance of the main contacts, requiring it to be ≤ 0.1 Ω. Exceeding the standard indicates contact wear, requiring cleaning or replacement.
• Protective Function: Check whether the lightning protection, moisture protection, and dust protection seals are intact (whether screws and gaskets are aged). Replace sealing components immediately if damage is found.

Quarterly Inspection

• Internal Component Inspection: After disconnecting the upstream circuit breaker, remove the protector casing and check the circuit board, coil, spring, and relay contacts for burning, oxidation, or looseness. Replace any damaged components found.
• Calibration and Reset: Use the calibration instrument provided by the manufacturer or professional calibration services to recalibrate the under-voltage/over-voltage thresholds and delay parameters.
• Recording and Reporting: Fill in all measurement data and maintenance/replacement situations from this inspection into the maintenance log to form a traceable record.

Annual Inspection

• Life Assessment: Judge whether to replace in advance based on the cumulative number of uses (e.g., if it is close to 50,000 mechanical life cycles).
• Environmental Assessment: Check whether the installation environment still meets the product's working temperature, humidity, and ventilation requirements; reassess if any changes have been made.

Conclusion

Understanding when overvoltage and undervoltage protectors need to be replaced helps maintain the safe operation of electrical systems. The factors mentioned earlier, such as frequent tripping, appearance damage, equipment aging and working environment, can all serve as references for determining whether replacement is needed.

Through regular daily maintenance and inspection, the service life of the protector can be extended, and potential hazards can be detected in time before problems occur. Regular inspection of equipment status and testing of protection functions are both effective preventive measures.

If any abnormal condition of the protector is found, it is recommended to contact a professional electrician for inspection. Replacing the protector requires a small investment and can prevent significant losses caused by voltage issues.