Electric Vehicle Fuse Applications

What Are EV Fuses?

Electric Vehicle (EV) and Hybrid Electric Vehicle (HEV) fuses protect electrical circuits, electrical equipment and batteries in an electric vehicle from electrical faults such as overloads and short circuits. The electrical circuits in Electric vehicles utilise direct current (DC) voltage. EV fuses often feature 500Vdc or 1000Vdc ratings. Like regular fuses, the voltage rating of an EV fuse is the maximum voltage for which the fuse is designed to operate. It will still work correctly in voltages below the maximum voltage rating.

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Difference Between EV Fuses and Standard DC Fuses

Electric vehicle fuses differ from common DC voltage fuses in several important ways;

EV fuses are built to be more robust to withstand vibration, g-forces, humidity etc. by constructing the fuse body using melamine laminated glass fibre rather than using ceramic casings commonly used for regular fuses.
The elements inside EV fuses are designed to achieve the required opening speeds and in-rush current handling demands of electric vehicles. This includes coping with thermal stresses and continuous current fluctuations. Fuses are specifically selected to ensure reliability and suitable protection.

Fuse Applications for Electric Vehicles

Fuses are required to protect electrical circuits in all types of vehicles regardless of whether they have petrol or electric engines. Components like lights, radio, electric windows etc. can be protected using standard automotive fuses.

Electric vehicles also require special purpose fuses for the protection of high capacity battery packs, electric motors, power conversion devices & battery charging equipment etc. These EV fuses are specially designed to ensure safe and reliable operation of the electric vehicle. The following image illustrates the type of fuses used in the power distribution unit and auxiliary systems of the vehicle.

Fuse Applications for Electric Vehicle Charging Stations

Battery operated electric vehicles require charging stations to recharge the batteries contained within the vehicle. These charging stations are also known as Electric Vehicle Supply Equipment (EVSE). EVSE devices require circuit protection devices to ensure that any potential overload or short circuit does not pose a risk to the vehicle, charging station or user. EV Charging Stations are generally categorised into 3 levels. The fusing requirements of each varies due to the voltage and current capabilities as shown below.

Level 1 Charging Station

Voltage:	Single Phase AC 120V
Peak Current:	16A
Charge Times:	6h to 24h

Level 2 Charging Station

Voltage:	Single or Three Phase AC 240V
Peak Current:	80A
Charge Times:	2h to 8h

Level 3 Charging Station

Voltage:	Direct Current DC 200V – 600V
Peak Current:	400A
Charge Times:	10min to 30min

Level 1 charging stations are typically a small adapter that charges the vehicle from a standard household power outlet. This type of charger takes many hours to fully charge the vehicle due to it's low current output. Level 2 and level 3 charging stations facilitate faster charging times using higher voltages and current.

Depending on voltage and current requirements of each charging station, different types of fuses are required. These fuses may range from 250VAC to 600VDC with peak current handling of 16A to 400A or more. One or more fuses may be located in the AC power input circuit and the DC power output circuits. Fuses protecting DC circuits are commonly very fast acting fuses to protect sensitive semiconductor components located in the circuit.

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