Standards

IEC 60947-1, EN 60947-1,
IEC 60947-4-1, EN 60947-4-1,
IEC 60947-5-1, EN 60947-5-1 (auxiliary switch)

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 vacuum contactors see "Accessories and Spare Parts" > "for SIRIUS 3RT1 Contactors and SIRIUS 3RH1 Contactor Relays", for 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 more information about vacuum contactors without overload relay, see technical specifications of the applicable contactors.

For short-circuit protection of the vacuum contactors with overload relay, see the Configuration Manual "Configuring SIRIUS – Selection Data for Fuseless Load Feeders", https://support.industry.siemens.com/cs/ww/en/view/40625241.

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.

Note:

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.

Note:

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

Motor protection

3RU11 thermal overload relays or 3RB2 electronic overload relays can be fitted to the vacuum contactors for protection against overload. The overload relays must be ordered separately, see "Protection Equipment" > "Overload Relays".

Ratings of three-phase motors

The quoted rating (in kW) refers to the output power on the motor shaft (according to the nameplate).

The power rating specifications of the vacuum contactors in kW are guide values for 4-pole standard motors at 50 Hz and specified voltage (e.g. 400 V AC). The actual starting and rated data of the motor to be switched must be considered when selecting the units.

Surge suppression

The vacuum contactors can be retrofitted with varistors for damping switching overvoltages in the coil.

Note:

The OFF-delay of the NO contact and the ON-delay of the NC contact are increased if the contactor coils are attenuated against voltage peaks (varistor +2 to 5 ms)

Vacuum contactors are basically unsuitable for switching DC voltage.

SIRIUS 3RT12 vacuum contactors, 3-pole, 110 to 250 kW

AC/DC operation

The contactors can be operated with AC (50 to 60 Hz) as well as with DC.

Two types of solenoid operation are available:

• Conventional operating mechanism, version 3RT12..-.A
• Solid-state operating mechanism, version 3RT12..-.N

Withdrawable coils

For simple coil replacement, e. g. if the application is replaced, the solenoid coil can be pulled out upwards after the release mechanism has been actuated and can be replaced by any other coil of the same size.

Vacuum interrupters

In contrast with the 3RT10 contactors – the main contacts operate in air under atmospheric conditions – the contact gaps of the 3RT12 vacuum contactors are contained in hermetically enclosed vacuum interrupters. Neither arcs nor arcing gases are produced. The particular benefit of 3RT12 vacuum contactors, however, is that their electrical endurance is at least twice as long as that of 3RT10 contactors. They are therefore particularly well suited to frequent switching in jogging/mixed operation, e.g. in crane control systems.

Auxiliary contact complement

The 3RT12 vacuum contactors of sizes S10 to S12 are supplied with laterally mounted auxiliary switch blocks.

These can be fitted with up to eight lateral auxiliary contacts (identical auxiliary switch blocks for S2 to S12 of the 3RT1 contactors). Of these, no more than four are permitted to be NC contacts.

3TF6 vacuum contactors, 3-pole, 335 to 450 kW

Main contacts

Contact erosion indication with 3TF68/3TF69 vacuum contactors:
The contact erosion of the vacuum interrupters can be checked during operation with the help of 3 white double slides on the contactor base. If the distance indicated by one of the double slides is < 0.5 mm in while the contactor is in the closed position, the vacuum interrupter must be replaced. To ensure maximum reliability, it is recommended to replace all 3 vacuum interrupters simultaneously.

Auxiliary contacts

Contact reliability:
These auxiliary contacts are particularly suitable for solid-state circuits with currents ? 1 mA at a voltage of 17 V and higher.

Protection of the main current paths

An integrated RC varistor connection for the main current paths dampens the switching overvoltage rises to safe values. This prevents multiple restricting. It can therefore be assumed that the motor winding cannot be damaged by switching overvoltages with steep voltage rises.

During operation in installations in which the emitted interference limits cannot be observed, e.g. when used for output contactors in converters, 3TF68/3TF69..-.Q vacuum contactors – without connection of the main current path circuit – are recommended.

Note:

The overvoltage damping circuit is not required if 3TF68/3TF69 contactors are used in circuits with DC choppers, frequency converters or speed-variable operating mechanisms, for example. It could be damaged by the voltage peaks and harmonics which are generated. This may cause phase-to-phase short circuits in the contactors.

Solution: Order special contactor version without overvoltage damping. The Article No. must include "-Z" and the order code "A02". Without additional price.

Control circuit

Protection of solenoid coils against overvoltages:

• AC operation:
  Fitted with varistors as standard
• AC operation with rectification:
  The rectifier bridge is connected to varistors for protection against overvoltages. The built-in rectifier bridge affords sufficient protection for the solenoid coils.
• DC operation:
  Can be retrofitted with varistors

For 3TF68 and 3TF69 with DC operation in the economy circuit (also for versions with AC operation with alignment), an additional reversing contactor 3TC44 is required, which switches the installed series resistor to holding excitation.

This reversing contactor is automatically included in the scope of supply in the same packaging as the contactor. The reversing contactor is connected to the 3TF6 main contactor by means of a one-meter connecting cable with plug-in connectors.