This electric arc is physically plasma at very high temperatures, which, besides maintaining the electrically closed circuit, wears down the contacts, greatly reducing their lifespan.
Several technologies exist to eliminate the electric arc created between contacts in DC circuits. Among these, compact contactors with contacts housed inside chambers filled with noble gases or in a vacuum have become popular. This gas prevents the formation of the electric arc, but it presents a problem. When high currents flow due to short circuits, overloads, or high operating conditions, the contacts heat up, transferring this heat to the gas. This effect can increase the gas pressure to such an extent that it could cause the contacts to burst.
SCHALTBAU, a contactor manufacturer with over 70 years of experience in DC voltages, possesses extensive know-how in arc-quenching techniques. Since high DC voltages have been used in the railway industry since its inception, system safety is vital to prevent explosions or failures in vehicles carrying hundreds of passengers. Therefore, SCHALTBAU has developed different technologies and opts for air-cooled switching instead of gas-cooled chambers.
Contactors for the railway environment require extremely robust mechanical characteristics and a very high number of switching cycles.
For applications in renewable energy, energy storage, and e-mobility, SCHALTBAU has developed a new family of air-commutated contactors. In this case, the mechanical requirements are not as stringent, and the number of switching cycles is geared towards use as a safety contactor. With the technology employed, it can be used as a bidirectional contactor, enabling safe switching of a DC circuit using only one pole.
The CS310 contactor family is launched for Ith currents of 150, 300, and 500 Amps on a normally open (NO) contact. Depending on the operating voltage, contact covers are used (for voltages up to 60Vdc) or arc-quenching chambers are used for voltages up to 1500V. This allows operation with peak currents of up to 3000 Amps/1 sec for opening, enabling short-circuit conditions to be withstood using slow-blow fuses without damaging the contactor. Switching currents can reach up to 2500 Amps, eliminating the need for contactors or pre-charge circuits to limit starting currents in highly capacitive systems. The use of auxiliary contacts is recommended for effective monitoring.
The benefits of this new family of DC contactors from SCHALTBAU, distributed by KOLBI, are:
• Safe switching of DC circuits up to 1500V.
• Bidirectional contactor that allows safe switching in applications where current flows in both directions, such as energy storage systems.
• High inrush current (up to 2500 Amps) eliminates the need for pre-charging circuits.
• Zero minimum critical current. Safely opens both large and small currents.
• High breakout current.
• Withstands high current spikes and overloads.
• Compact size.
