Upon tripping, the PTC heats up, increasing its resistance and effectively breaking the circuit. This allows only a minimal leakage current to pass through, significantly less than the 3A that could potentially be allowed by a short. Once the short is removed, the PTC resets, allowing the regular flow of current up to 250mA. This makes the PTC an effective resettable fuse that can protect your system, particularly beneficial for battery-powered devices that require protection against high-current accidental discharges.
The effectiveness of the PTC can be visually demonstrated through thermal imaging. In a normal state, a voltage regulating circuit maintains a regular temperature. However, when shorted, the PTC significantly heats up as it works to limit the damaging current flowing through the circuit. This visual representation clearly shows the protective function of the PTC in action, effectively preventing potential harm to your electronic system.
For more detailed information, consult the PTC RXE025 document provided by Sparkfun.