Siemens Mini Contactor 3TF2 sample

Brief introduction of Siemens micro contactor 3TF2

This type of Siemens contactor has three different types of connection methods: screw terminals, 6.3mm plug-in terminals and solder pin connections for soldering to printed circuit boards, and the 3TF2 miniature contactor has a climate protection function and meets the IEC60529 standard.

◆Executive standards

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

Specifications of Siemens Micro Contactor 3TF2

◆Connection type

1. Flat connector 6.3x0.8mm;

2. Screw terminals;

3. The solder pin connection of the printed circuit board.

◆Type of control power supply voltage

1. DC;

2. 50Hz (60Hz) AC;

3. 50Hz/60Hz AC;

4. 50Hz/60Hz AC (United States + Canada).

◆Rated control power supply voltage

12V DC;

24V AC/50Hz and 29V/60Hz;

24V AC/50 or 60Hz;

24V DC;

42V AC/50Hz and 50V/60Hz;

48V AC/50Hz and 58V/60Hz;

48V DC;

52V DC/with varistor;

60V DC;

110V AC/50 or 60Hz;

110V AC/50Hz and 132V/60Hz;

110V DC;

120V AC/60Hz and 110V/50Hz;

220V AC/50 or 60Hz;

220V DC;

230V AC/50 or 60Hz;

230V AC/50Hz and 277V/60Hz;

230V DC;

240V AC/60Hz and 220V/50Hz;

◆Auxiliary contacts

1NC, 1NO, 1NO+1NC, 2NO+2NC.

Siemens micro contactor 3TF2 surge suppression

RC elements, varistors, diodes or diode components (combination of diodes and Zener diodes for short break time) can be inserted into all Siemens contactors 3TF2 and auxiliary switch blocks, with screw terminals on the front end to suppress open circuits in the coil surge. Note: If the contactor coil is attenuated for voltage peaks (suppression diode 6x to 10x; diode assembly 2x to 6x; varistor +2 to 5ms), the OFF delay time of the NO contact and the ON delay time of the NC contact increase.

Siemens mini contactor 3TF2 auxiliary switch

All 3TF2 miniature contactors have an integrated auxiliary contact 1NO or 1NC. Siemens contactors with screw terminals can be expanded to include snap-on auxiliary switch blocks. They also provide pre-installed auxiliary switch blocks.

Contactors with screw terminals with NO contacts (ID 10 in accordance with EN 50012) can be expanded to miniature contactors with 2, 4 and 5 auxiliary contacts, in accordance with EN 50012, using auxiliary switch blocks. The identification numbers 11, 22, 23 and 32 on the coded auxiliary switch block apply to the complete miniature contactor (see figure below). These auxiliary switch blocks cannot be used in combination with the miniature contactor with identification number 01.

All miniature contactors with screw terminals and identification numbers 10 or 01 can be expanded to Siemens contactors with 3 or 5 auxiliary contacts, in line with EN 50005. Using auxiliary switch blocks 40, 31, 22, 20, 11, and 02, auxiliary switch blocks are only applicable to connected auxiliary switches.

Siemens Mini Contactor 3TF2 FAQ

Question: How many auxiliary contacts can be connected in series on the control and auxiliary circuits of Siemens contactors?

Answer: There is a greater risk of potential failure when multiple contacts are used in series, because each contact has a specific transition resistance. The total voltage drop caused by these contacts in series may reach one that will affect the load. Or the value of the input signal. When multiple contacts need to be connected in series in the application (for example: enable or emergency stop circuit), appropriate measures should be taken to limit the number of contacts directly connected in series. For example, on the controller, the contacts on a loop can be distributed to multiple input terminals, or the number of contacts can be increased in another way. Therefore, it is difficult to specify the maximum allowable number of series contacts as an accurate number. Because this is related to many factors, such as current, voltage or other environmental conditions. Based on the experience and feedback provided by the on-site engineer, a series of less than 10 contacts can be used. In addition, two contacts can be used in parallel to improve the reliability of the contacts.

Question: How will the current carrying capacity change when Siemens contactor contacts are used in series or in parallel? How to choose?

Answer: When the contactor contacts are used in series, a certain amount of current is allowed to pass, and the voltage value can be increased (contactor technical sample data description). The reason is that the arc of the contactor is divided into a certain number of small arcs, and the specific situation depends on how many poles the actual contactor is connected in series. Series contactor contacts can also reduce contact erosion, thereby increasing the service life of the contacts, and are generally used for DC loads.

The parallel connection of equipment contacts will not close or open at the same time due to poor mechanics. The contacts of the parallel contactor will neither increase the closing capacity nor the opening capacity of the contactor. The connection mode given in the following examples is the upper limit of the increase in contactor contact closing or opening capacity. Connecting contactors in parallel can be used to increase the continuous (thermal) current of the contactor.

The contactor AC-1 increases the current as follows:

-Two poles in parallel: IeAC-1x1, 8.

-Three poles in parallel: IeAC-1x2, 5.

In order to avoid current imbalance, we recommend only connecting adjacent lines in parallel.

For example, using two three-level contactors to connect each phase in a three-phase system in parallel:

Phase L1: Connect the L1 and L2 levels of the first contactor.

Phase L2: Connect the L3 level of the first contactor and the L1 level of the second contactor.

Phase L3: Connect the L2 and L3 levels of the second contactor.

Question: How to calculate the power loss of Siemens contactor 3TF?

Answer: The thermal power consumption of the contactor can be calculated in the following way.

－DC operation contactor: the holding power of magnet coil.

－AC operation contactor: magnet coil holding power × power factor.

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