What requirements do relays in e-mobiles have to fulfill

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FAULHABER Antriebssysteme

MEV Elektronik Service GmbH

RECOM Power GmbH

TE Connectivity

The dielectric resistance of new contactors is normally in the region of several hundred giga ohms. After the normal lifetime of the BDU (10 cycles/day for 15 years), the dielectric resistance must not fall below a defined minimum value. In the event of overload or malfunction, the precharge or main contactors must be capable of disconnecting the entire load between the battery and electrical system or the DC rapid charge contactor (DC-LS) between the on-board charge module (OBCM) and the battery. The high energy arcs occurring during disconnection cause vaporization of the contact material, which deposits on the inner walls of the contact cavity. This can lead to a reduction of the dielectric resistance and strength.

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ISO 6469-3 specifies a minimum dielectric resistance of 500 Ω/V for AC voltages and 100 Ω/V for DC voltages. Reference is also often made to LV124. The dielectric resistance specified here is considerably higher and is about 5 MΩ for DC systems. The dielectric strength of the contactor must be maintained after conditioning and load tests; the test voltage required for the basic insulation is calculated using the equations (2 Umax + 1000) [VAC] and (2 Umax + 1000) 1.41 [VDC].

New developments are designed with appropriately dimensioned clearances and creepage distances in particular for the insulation requirements of DC voltages in electric vehicles. They also fulfill the specific battery management overload requirements and are therefore particularly suitable for the applications described above.

TE Connectivity also offers an extensive relay portfolio for virtually all areas of application as well as highly qualified technical support by the application department for customer-specific product modifications and new developments.

* Dr. Mihail Brezeanu works as Application Engineer at TE Connectivity in Berlin

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