Soft starts give near-linear speed ramp and no torque peaks

WEG Electric Motors (UK) Ltdvisit website


WEG says it has developed a new technology known as Totally Flexible Torque Control (TFTC) for its new 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 the WEG SSW-06 Soft-Starter is called Totally Flexible Torque Control 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.

Furthermore, 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.

Market leader

This flexibility to choose the desired torque curves, combined with all the protection required for an induction motor, makes the application of the SSW-06 soft-starter possible on practically any type of load that does not require speed variation after starting. It also makes the WEG SSW-06 soft-starter one of the most advanced soft-starters available on the market today.

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 per cent smaller than one used in the standard connection made 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. This integrated feature is complemented by many others in the overall SSW-06 package, including: a kick-start function for heavy loads, and loads requiring high starting torques; a pump control function that avoids water hammer; multi-motor starting capability; electronic motor protection; an electronic thermal relay; and a detachable HMI that offers easy operation for programming and troubleshooting.

Easy programming and copying

The HMI is multi-language unit, 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 in other countries. In addition, the intelligent interface also incorporates a copy function that permits copying of the parameters from 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 SSW-06 users.

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 22-475kW. 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 220-575V (85–365A). 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.

14 August 2007

WEG Electric Motors (UK) Ltdvisit website
See all stories for this company
© Copyright 2006-14 Damte Ltd.