Safe networks

Contactors are used as remote-controlled switches to frequently switch high currents and voltages. They are used to galvanically isolate electrical circuits and to protect circuits from overloads.

Because they may be heavily loaded, contactors have special design requirements; e.g., they must have a high making and breaking capacity, be capable of conducting high conventional thermal current, have high contact-temperature ratings and be able to safely break a short circuit. When the current is interrupted, an arc is formed, which must be quickly extinguished.
Switching off high DC voltages is particularly challenging. It is precisely in this field that our many years of experience with railway applications have enabled us to become specialists. Mastery of the electrical arc is one of our core competencies.

Schaltbau's contactors have additional features, such as:

high quality and performance
a wide range of coil voltage tolerance (from +25 to -30 %)
excellent coil suppression, standard feature using varistors
designed for harsh environments
high shock and vibration resistance
optional auxiliary contacts available

Compact contactors

Our compact contactors are used to switch to battery or fuel-cell backup circuits when electronic data processing systems lose power. More

Switching high DC voltages

When breaking under load, an arc is formed that can reach temperatures of up to 10,000 °C. This arc must be quickly extinguished (less than ten milliseconds) to prevent contact platings from melting. The zero-crossing that occurs every half cycle with an AC voltage is useful in this regard. Since there is no zero-crossing for DC voltages, other techniques must be employed.

An arc is essentially electrical current flowing through ionized air. Permanent magnets are used to stretch the arc and thereby extinguish it. Arc-chutes are required for higher voltages. These stretch, cool and disperse the arc. Most arc chutes are made using small metal plates and additional blowout magnets.

Follow the links for further information about Schaltbau's contactors