Very Compact Thyristor Modules

26th November 2006

Semikron Ltd

ES Admin

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SEMIKRON has introduced its SEMiSTART family of anti-parallel uninsulated thyristor modules, which has been designed specifically for use in soft-start devices. The modules are extremely compact. For example, a 400kW soft-starter featuring SEMiSTART is only one-sixth of the volume of the same device using conventional capsule thyristors. In addition, by using pressure contact technology and double-sided chip cooling, these new modules can withstand overload currents of up to 3000A for up to 20s

SEMiSTART is available in three different module sizes and five different current classes. The smallest module sizes are for overload currents of up to 560A, while the largest can withstand up to 3000A with an overload duration (during start-up phase) of 20 seconds. The maximum blocking voltages are 1400V and 1800V.

The much lower thermal resistance Rth(j-s) in these modules is achieved by directly pressing the thyristor chips between two heat sinks using pressure-contact technology. This allows for highly-compact designs and robust and reliable systems with optimised chip cooling. The heat sinks also double as electrical connectors. The new modules have fewer contact layers overall, meaning that they have less thermal contact resistance than conventional solutions – for example, the thermal contact resistance between the flat thyristor case and heat sinks in conventional solutions. The total thermal contact resistance in these modules is less than half that of insulated semiconductor modules with similar-sized thyristor chips, because there is no electrical insulation to hinder heat dissipation from the chip to the heat sinks.

SEMiSTART modules are easily mounted, because the mounting clamps needed for capsule thyristors and the thermal paste used in semiconductor modules are not necessary.

This new product family is compliant with the provisions of the RoHS and WEEE EU Directives.