Switching Duties

Vacuum contactors are suitable for operational switching of alternating-current consumers in indoor switchgear

Switching of three-phase motors in AC-3 or Ac-4 operation

eg in conveying and elevator systems, compressors, pumping stations, ventilation and heating)
Vacuum contactors are especially suitable for frequent operation of motors. As the chopping currents of the contactors are ≤ 5 A, no unpermissibly high overvoltages are produced when started motors are switched during normal operation. However, when high-voltage motors with starting currents of ≤ 600 A are stopped during start-up, overvoltages may arise. The magnitude of these overvoltages can be reduced to harmless
values by means of special surge limiters.

Switching of transformers

e.g. in secondary distribution switchgear, industrial distributions)
When inductive currents are interrupted, current chopping can produce overvoltages at the contact gap. Such overvoltages can be controlled with a protective circuit composed of 3EF surge limiters.

Switching of capacitors

(e.g. in power factor correction systems, capacitor banks)
3TL vacuum contactors can interrupt capacitive currents up to 250 A up to the rated voltage of 12 kV without restrikes, and thus without overvoltages.

Switching of reactors

(e.g. in industrial distribution systems, DC-link reactors, power factor correction systems)

Switching of resistive consumers

(e.g. heating resistors, electrical furnaces)