An electric vehicleís circuit breaker is primarily the safety switch used to switch off the mechanisms in the electric vehicle in the event of a short-circuit or an accident. This serves as an important component when a vehicle is operating, and should always be double-checked if itís running properly. The generic function of these circuit breakers also help remove power from a faulty system, which is often abbreviated as an OCPD (Over Current Protection Device). Without such a safety component, there is a risk for an EV to undergo a battery overload. However, what makes the modern circuit breakers today different from the fuses is the fact that theyíre not resettable.
There are many modern standards today on what circuit breakers should have, do or render. According to modern standards on IEC 60364-7-72, EV circuit breakers should have every connection point (plug sockets) fit the standard own residual current operated protective device (RCD) that has a residual current rate of I∆n ≤ 30 mA. That said, there also has a safety precautionary procedure to protect the case of the smooth DC residual currents of these circuit breakers, especially when they have a higher than 6 mA rating.
The circuit breakers available in the EV market today are known for their varying designs, sizes and brands. From small devices to large EVs, these circuit breakers make the difference in protecting the voltage circuits that may lessen the complete lifespan of EVs. Similarly, there are multiple types of these circuit breakers, based on their voltage class, structural features, interrupting type and the type of construction they have.
The low-voltage types of circuit breakers have about less than 1,000 VAC and are commonly found in domestic, commercial and industrial settings. These circuit breakers include the Miniature circuit breakers (MCB), which have a current rating of up to 125 A and a set of trip characteristics that you canít easily adjust. Theyíre also typically operating in a thermal-magnetic system.
The Molded Case Circuit Breaker (MCCB) is a low-voltage type thatís available in the market and has a current rating of about 1,600 A. Itís still made to run under a thermal or thermal-magnetic set-up. Thereís another type of circuit breaker today thatís called a solid-state circuit breaker, which is more popularly called a digital circuit breaker. Being called as technologically innovative, the promise of these circuit breakers is that theyíre able to serve the circuit in fractions of microseconds and will provide a better monitoring of circuit loads and longer lifetimes to any EV that uses it.
We should mention that the magnetic circuit breakers today are using a solenoid electromagnet design. Whatís interesting about this type is that it offers a pulling force that increases the current of the EV even if itís held close by a latch. The interaction between the solenoid and the rating of the circuit breaker makes the function of this circuit breaker even more ideal in settings that require EVs to even be more heavy duty, such as in industrial settings in the United States.