CT power contactors – Revolution in handling DC and AC electric arcs

Single and double pole NO contactors for AC and DC (bidirectional). Rated insulation voltage up to 4,800 V; conventional thermal current up to 1,100 A.

Single pole NO contactors for AC and DC (bidirectional). Ui = 1,500 V, Ith = 400 A.
Single pole make contact contactors for AC and DC (bidirectional). Ui = 3,000 V, Ith = 1,100 A. Heat sink on both main connections.
Double pole NO contactor for AC and DC (bidirectional). Ui = 1,500 V, Ith = 400 A.
Double pole NO contactor for AC and DC (bidirectional). Ui = 3,000 V, Ith = 1,100 A. Heat sink on both main connections.

The outstanding feature of the CT range is the unprecedented combination of electromagnetic and permanent-magnetic blowout in one device. In contrast with power contactors with only electromagnetic blowout, the electric arcs are ignited in strong permanent-magnetic blowout fields at the moment of shutdown.

The dwelling times of the electric arcs in the contact zones are thus kept to an absolute minimum. This leads to a significant reduction in shutdown combustion residue. This less wear on the contact surfaces allows for extended maintenance intervals.

The CT concept can be flexibly adjusted to the requirements of customers; e.g. the number of poles, auxiliary contact design or connection technology. The product family of the single and two-pole CT contactors covers a large number of different designs for a wide number of areas of application.


Regardless of the direction of the current

Thanks to the mirror-image design the CT contactor functions regardless of the direction of the current. Unidirectional or bidirectional direct current or alternating current can be switched with the same device.

Low-wear, compact design

The arcs dwell for an extremely short time in the contact zones because they are already ignited in a powerful permanent magnetic field. Burn-up on the contacts is thus kept to a minimum.

The arc itself activates the electromagnetic fields that blow it into the arc chute. Thus the coils only need to feed high current for a minimal amount of time and can therefore be relatively lightly constructed. No additional mechanical or electrical elements are required (advanced contacts, wires, etc.). Thus wear-sensitive components can be omitted and the design remains relatively straightforward and compact.

No critical current range

The CT range also shows its strengths in the reliable shutdown of smaller currents at higher voltages. With smaller currents, the magnetic field of the electromagnets does not suffice. By using permanent magnets, the electric arc is pushed into the electric arc chamber regardless and extinguished. The critical current range typical for purely electromagnetic blowout concepts is not available in the CT.

Power switches in rail and industry

CT contactors are used in various railway networks around the world. However, they are also valued as safety power switches in industry:

  • Test benches for high-voltage systems of electric vehicles (main contactor)
  • Energy store: disconnection of the intermediate circuit (two-pole CT)


Type of voltageDC (bidirectional), AC (f < 60 Hz)
Contact configuration1 x SPST-NO or 2 x SPST-NO
Nominal voltage Un1,500 V or 3,000V
Rated operating voltage Ue1,800 V or 3,600V
Rated insulation voltage UNm3,000 V or 4,800V
Rated impulse withstand voltage UNi15 kV or 30 kV
Pollution degree / Overvoltage categoryPD3 / OV3
Conv. thermal current Ith400A, 800A oder 1,100A
Component categoryA2
Short-circuit making capacityseries-specific, see catalogue
Contact material main contactsAgSnO2
Aux. contact1x S870&nbsp;(a1), 1x S870&nbsp;(b0), 2x S826 or 4x S826
Coil voltage Us24, 36, 72, 110 V DC
Coil tolerance Us-30% ... +25%
Coil power consumptionseries-specific, see catalogue
Coil suppressionSuppressor diode / double coil controller (DCC)
Mechanical enduranceseries-specific: 300.000 min. / 2.000.000 max. operating cycles
Vibration / Shock (IEC 61373)Category 1, class B
Mounting orientationhorizontal / vertical
IP rating (IEC 60529)IP00
Temperature range-40 °C ... +70 °C
Storage temperature-40 °C ... +85 °C
Weightseries-specific, see catalogue

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CT – power contactors for AC and DC (bidirectional) up to 4.8 KV and 1,100 A