The fuses that are designed for EVs are important because they serve as a backup to the circuit breaker, and are usually made with an average conversion of at least two fuses for safety. Like circuit breakers, these fuses will serve as a protection when there’s a short circuit or power overload. You can get a replacement of these fuses at about $30 a piece.
What’s interesting about fuses is that they’re like a sacrificial device. Once they’re used up or broken, you have to replace or rewire them, depending on the type. These fuses are essential safety devices at the onset of electrical engineering, and are still vital in the safe running operations of electric vehicles. This safety security won’t be a problem since there are many regulatory bodies already that monitor the normal running operations of these electrical installations. These regulations include the BS 7671 UK wiring regulations, the IEC 60364 IEC international standard, the Canadian Electrical Code (CEC) and the U.S. National Electrical Code (NEC).
It’s useful, too, to know the difference between fuses from circuit breakers. For starters, fuses are much less costly, but can be less convenient that circuit breakers that are easily just resettable when there’s a faulty electric charge. There’s a bit of harm, too, in replacing a fuse without properly isolating the switches for each fuse. It’s dangerous, and particularly so, when the issue is a short circuit problem.
There’s more maintenance in circuit breakers compared to fuses. Fuses just rely on their natural melting processes and will require no mechanical operation on your part even if they’re under faulty conditions. There is another option, for example, that the other parts of a multiple set of fuses can still be operating if just one fuse is actively in use. Circuit breakers will not be able to do something like this.
There is what is called a current-limiting fuse, which operates so quickly that it can limit the total “let-through” that passes into the circuit. When this happens, there is a protection system that takes place and that will protect the downstream equipment from any type of damage. The fuses only open in less than one cycle of the complete AC power frequency, which is a rate speed that no circuit breaker can match today.
While fuses vary, there’s a uniform set of rule-of-thumb ratio to follow when several fuses are being connected to the power distribution system in a fuse series. This installation process to form the series of fuses for an EV is what is called a “coordination” or “discrimination”. The mix of these different types of fuses in a series will allow for a minor branch of the fuse to disconnect its circuit when the major fuse starts to melt. This system allows for a better protection mechanism that lengthens the complete lifespan of an EV.
Fuses have what is called a fuse protector or what is called a “self-resetting” feature that will use a thermoplastic conductive element technically called a Polymeric Positive Temperature Coefficient (PPTC) thermistor. What this feature does is it impedes the circuit running the EV during instances of an overcurrent.