Recently, at a customer’s special request, our 20PTMOV150/S (thermally protected MOV), rated at Uc/MCOV 150VAC, was subjected to an abnormal overvoltage of 1000VAC. Under this extreme electrical stress far beyond its rated conditions, the 20PTMOV still tripped as designed, and the built-in Prosurge patented technology successfully extinguished the resulting arc, demonstrating a safe failure mode under severe fault scenarios.

Test Procedure and Key Observations

During the 1000VAC application, the MOV chip inside the 20PTMOV conducted due to overvoltage and quickly heated up. The thermal disconnector activated in a timely manner. At the moment of tripping, a brief arc appeared across the MOV circuit, but the built-in thermal mechanism promptly interrupted the circuit and extinguished the arc. No housing rupture, fire, or sustained short circuit occurred.

At 0.05 seconds into the test video, the clamp meter (measuring current) showed a momentary flicker, indicating that current briefly passed through the MOV chip during the tripping event. Immediately afterward, the current reading dropped to zero, confirming that the thermal disconnector had completely opened the internal circuit of the 20PTMOV. This phenomenon is critical – incomplete disconnection would allow the fault current to rise continuously, eventually leading to a short circuit and burnout of the SPD, or even a more serious safety incident.

Technical Significance

This test simulated an abnormal overvoltage far exceeding the SPD’s rated Uc/MCOV, placing high demands on the device’s thermal trip response speed, arc suppression capability, and fault isolation performance. The 20PTMOV’s ability to achieve complete disconnection under 1000VAC (approximately 6.7 times Uc/MCOV) fully validates:

Reliable operation of the thermal disconnector under extreme overvoltage conditions;

Effectiveness of the arc extinction design under high-energy discharge;

Achievement of a “fail‑open” safe state after a fault, preventing fire and secondary damage to the system.

Customer Value

For SPD manufacturers and end users, the “safe failure” feature of the 20PTMOV means that even in rare and severe electrical faults, the device actively disconnects itself from the circuit, minimizing risks. This provides a higher level of protection redundancy for applications such as power systems, industrial automation, renewable energy, and telecommunications base stations.

For more information about PTMOV products or safe failure testing, please contact our technical team via the company website.