Soft starter feature new torque technology

Edited by the Engineeringtalk editorial team Aug 15, 2007

TFTC offers the advantage of providing a practically linear speed ramp during the entire motor starting process, avoiding torque peaks that can produce abrupt accelerations

WEG has developed a new technology known as TFTC - Totally Flexible Torque Control (TFTC) - for its new generation SSW-06 soft starter.

Employing the same vector and direct torque control concepts used largely in WEG's variable frequency drives, TFTC offers the advantage of providing a practically linear speed ramp during the entire motor starting process, obviating torque peaks that, depending on the type of load, can produce abrupt accelerations.

The torque control function of WEG SSW-06 Soft-Starter is called TFTC because it offers the flexibility of selecting the type of torque control desired according to the type of load applied to the motor; as, for example, constant loads, quadratic loads, or loads with lower or higher initial torques.

The combination of TFTC and, the same 32 bit DSP employed in WEG's variable frequency drives, means that torque estimation by the SSW-06 soft-starter is very true to the real torque developed by a motor during its entire starting process, allowing the implementation of more advanced control techniques.

These techniques provide for the adjustment of the torque curve developed by the motor to the torque curve required by the load during the starting process.

As a result, it is possible to have a constant accelerant torque, which will produce a practically linear speed ramp.

This flexibility to choose the desired torque curves, combined with all the protection required for an induction motor, makes the system suitable for any type of load that does not require speed variation after starting.

In addition to TFTC, and its 32-bit control capability, the SSW-06 offers maximum convenience and cost saving with its ability to fit into the Delta connection of existing motor starters (six leads).

This offers the advantage that the soft starter can be 43% smaller than one used in the standard connection mode with three leads.

As a further aid to competitiveness, the SSW-06 is designed with a by-pass contactor (85A to 365A) that offers the advantages of reducing the installation envelope of the soft starter, and increases energy savings.

Other features include a kick-start function for heavy loads and loads requiring high starting torque; a pump control function which avoids water hammer; multi-motor starting capability; electronic motor protection; an electronic thermal relay; and a detachable HMI, which offers easy operation for programming and troubleshooting.

The HMI is multi-language, which is an advantage for OEMs who can choose language options such as German, Spanish, English and Portuguese in order to adapt the soft starter for use anywhere in the world.

In addition, the intelligent interface also incorporates a copy function that permits copying of the parameters in one soft starter to another, allowing faster and more reliable programming in OEM applications where serial machines are involved, and greater back-up security generally for the SSW-06 user.

A range comprising 28 different models means that the SSW-06 soft starters can cater for the majority of motor starting requirements, in the power range from 22kW to 475kW.

Conveniently for OEMs, all the models in the range are rated for both 50Hz and 60Hz operation, with the choice of 11 supply voltages from 220V to 575V (85A - 365A).

The soft starters meet all the requirements of UL 508,cUL, IRAM and C-tick for industrial control equipment, IEC 60947-4-2 and the European EMC directive 89/336/EEC.