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135A / 450Vdc Contactor for EV and Transportation Systems

June 16, 2017

Fuji Electric Co., Ltd. has released a high-voltage contactor capable of delivering the highest current overload capacity in the industry for more reliable vehicle operation. Capable of handling 450Vdc, the SVE135 is rated for 135A. Its breaking performance is 400A / 450Vdc (50 times) and is symmetrical with equal breaking performance in both directions. It has an overload capacity of 20kA for 50ms.

The SVE135 was designed for use in next-generation automobiles (e.g. electric vehicles, hybrid vehicles, plug-in hybrid vehicles, fuel cell vehicles) and in transportation equipment mounted with secondary batteries (e.g. forklifts, construction equipment, automated guided vehicles).

Electric and hybrid vehicles are becoming increasingly popular around the world. Because these next-generation automobiles are equipped with high-voltage, high-capacity batteries, maintaining and improving their safety is a critical concern. Meanwhile, automakers are demanding more compact, lightweight vehicle body structures to help boost fuel efficiency and extend cruising range.

Conductors are devices that open and close the electrical circuits that link the battery to the inverter and the motor. Fuji Electric forecasts that global market for automotive contactors would grow at least 30% a year and sales would reach at least JPY 70 billion by 2020.

Fuji’s factory in Kounosu, Saitama Prefecture is equipped with Japan’s leading short-circuit breaking test equipment. This gives the company the ability to better support customer product development, since it is able to carry out high-current short-circuit withstand capability tests and breaking tests for battery charge/discharge circuits that include the SVE135 high-voltage contactor.

When a vehicle breaks down or gets into an accident that results in a short circuit and overcurrent, magnetic forces (electromagnetic repulsion) cause the contact of the contactor to be lifted, which may generate a massive arc (discharge phenomenon) of several thousand or even several tens of thousands of amperes. The SVE135, however, features a unique contact structure that compensates electromagnetic repulsion-allowing it to deliver an industry-leading 20,000 amperes of withstand capability. The result is a contactor with significantly reduced risk of rupture and/or fire.

Although an arc is generated when the circuit is interrupted (when contact points open), the structure of the SVE135 features sealed contact block that prevent sparks from the arc from shooting out of the device while also preventing dust contamination. It also includes a gas that boosts breaking performance within the sealed contact block, making distance required for electrical interruption shorter than it would be with an air circuit breaker and allowing for the kind of compact design required in today’s automotive applications.

Magnetic force from a permanent magnet installed in contactors lengthen arcs generated during breaking in order to extinguish them, but in the past, there was an issue with these devices having different breaking performance depending on the direction of the current (charging vs. discharging). Fuji has been able to achieve equal breaking performance in both directions with design that improves permanent magnet configuration, for example. This brings flexible installation to battery charge/discharge circuits, which in turn allows for easier circuit design customization.

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