Power contactor AC-3 40 A 18.5 kW/400V 3RT1035-3AD20

Power contactor, AC-3 40 A, 18.5 kW / 400 V 42 V AC, 50 / 60 Hz, 3-pole, Size S2, Spring-type terminal !!! Phased-out product !!! Successor is SIRIUS 3RT2

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Power contactor, AC-3 40 A, 18.5 kW / 400 V 42 V AC, 50 / 60 Hz, 3-pole, Size S2, Spring-type terminal Successor is SIRIUS 3RT2 3RT10353AD20_datasheet_en



IEC/EN 609471, 
IEC/EN 6094741, 
IEC/EN 6094751 (auxiliary switches)

The SIRIUS 3RT12 and 3TF68/3TF69 vacuum contactors are suitable for use in any climate. They are finger-safe according to IEC 60529.

Terminal covers may have to be fitted onto the connecting bars, depending on the configuration with other devices. Terminal covers for 3RT12 and 3TF6 vacuum contactors, see “Accessories and Spare Parts” → “for SIRIUS 3RT12 and 3TF6 Vacuum Contactors”.

Connection method

The vacuum contactors are available with screw terminals (box terminals).

Contact reliability

If voltages ≤ 110 V and currents ≤ 100 mA are to be switched, the auxiliary contacts of the vacuum contactors or 3RH contactor relays should be used as they guarantee a high level of contact reliability.

These auxiliary contacts are especially suitable for solid-state circuits with currents ≥ 1 mA at a voltage of 17 V and higher.

Short-circuit protection

For short-circuit protection of the vacuum contactors with or without overload relays, refer to the Manuals and Configuration Manuals, see Technical specifications.

Electromagnetic compatibility (EMC)

The contactors with solid-state operating mechanism comply with the international standards IEC/EN 60947-1, IEC/EN 60947-4-1.

These contactors have been developed for environment A.


Environment A refers to private low-voltage or industrial networks/locations/plants, including high-grade sources of interference.

Environment A corresponds to devices of Class A with CISPR 11, EN 55011.


In connection with converters, the control cables must be routed separately from the load cables to the converter.


Normal operating conditions

The standard contactors 3TF68 ..-.C.. and 3TF69 ..-.C.. for AC operation are fitted with an electronically controlled solenoid operating mechanism with a high interference immunity. The solenoid coil is connected to varistors for protection against overvoltages.

Electromagnetic compatibility


Rated control supply voltage Us

Overvoltage type
(IEC 60801)

Degree of severity
IEC 60801

Overvoltage resistance


110 V … 132 V



2 kV
6 kV


200 V … 277 V



4 kV
5 kV


380 V … 600 V



4 kV
6 kV

Operation with AC control supply voltage that is particularly subject to strong interference

Contactors 3TF68 ..-.Q.. and 3TF69 ..-.Q.. for AC operation are envisaged for operation in systems with AC control supply voltage that is particularly subject to strong interference. The solenoid systems of these contactors are configured in the DC economy circuit with rectification. The rectifier bridge is connected to varistors for protection against overvoltages.

Such interference can be caused, for example, by the following:

  • Periodic overvoltages are injected into the control level of the contactors in the vicinity of operating frequency converters.
  • High-energy individual pulses from switching operations and atmospheric discharges are carried over the control cables.

To reduce interference caused by frequency converters, the manufacturer recommends the provision of, for example, input filters, outputs filters, grounding or shielding in the plant.

Other measures that have to be taken for overvoltage damping:

  • Contactors supplied via control transformers in accordance with EN 60204 – not supplied directly from the grid
  • Use of surge arresters, if applicable.

If operating conditions are such that high levels of interference are created and no measures have been taken to reduce the interference injection into the control voltage level, use of the 3TF68..-.Q and 3TF69..-.Q contactors is especially recommended.

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