For patch fuses with the same current and volume, is the voltage at which they quickly break higher than that at which they slowly break?

In electronic circuit design, selecting the appropriate patch fuse is a fundamental and critical task. Many engineers have discovered an interesting phenomenon: under the same rated current and physical volume conditions, the rated voltage value of fast break surface mount fuses is often higher than that of slow break fuses. This is not accidental, as it contains a profound consideration of the circuit protection characteristics.
To understand this phenomenon, we first need to understand that the core function of patch fuses is to safely and reliably cut off the circuit in the event of abnormal current. The process of "cutting off" is essentially the melting, gasification, and arc generation of the fuse element under the heat generated by overcurrent, and ultimately extinguishing the arc to complete the circuit breaker. The rated voltage is the indicator for measuring the safe arc extinguishing ability of surface mount fuses.
The main difference between fast break and slow break patch fuses lies in their melt structure. The melt design of fast breaking surface mount fuses is narrow and extremely sensitive to current changes, and can quickly melt when overload current occurs. This rapid action means that the arc is generated at a lower energy level and needs to be extinguished more quickly. Therefore, in order to ensure instantaneous and safe arc extinguishing even in high voltage environments, and to avoid reignition or arc pulling, the internal arc extinguishing material (such as quartz sand) and melt structure of fast break surface mount fuses are designed to withstand higher voltage stress.
In contrast, slow break surface mount fuses, also commonly known as delay fuses, typically have a more complex structure in their fuses, such as connecting high-quality solder joints at narrow points. This design allows it to withstand brief current surges (such as surge currents during device startup) without melting. However, when a truly sustained overload occurs, it takes longer to accumulate enough heat to achieve a circuit breaker. This longer melting process means that the arc energy may be higher and the duration may be longer. Under the same physical volume constraints, designing a high-voltage structure that can safely and reliably extinguish this potentially more "stubborn" arc is technically more challenging. Therefore, manufacturers usually set a relatively conservative and lower rated voltage value for slow break surface mount fuses of the same specifications.
In summary, the rated voltage is directly related to the arc extinguishing ability of the surface mount fuse. The quick break type has a fast action and relatively low arc energy, making its structure easier to achieve reliable breaking under high voltage; However, the slow break type is limited by its delay characteristics and potential higher arc energy. Under the same volume, the setting of its voltage rating will be more cautious. Therefore, when choosing a patch fuse for your circuit, not only should you pay attention to the current value, but you must also combine the working voltage and load characteristics of the circuit to comprehensively judge the fast break and slow break types, in order to ensure the best protection effect and system safety.