Siemens Automation and Drives (A&D) is introducing a new series of high-performance torque motors for drive applications with high torques or low speeds of rotation. The motors from the HT-direct series are based on permanent-magnet technology and exhibit compactness, ease of installation and maintenance, reduced noise emissions and up to 3 per cent greater efficiency compared to geared alternatives. Moreover, the low-maintenance design of the motors substantially increases availability.
The use of direct drives is often advantageous, especially where high torques and low speeds are involved. Typical examples are presses and rollers in paper machines, cutters, edgers, winders and small rolling installations in the steel industry, as well as pumps and fans, plastic extruders, sugar centrifuges and gear testing benches. Direct drives for high torques can best be implemented with synchronous machines based on permanent magnet technology. In contrast to induction machines whose reactive power requirement grows as the number of poles increases, a high-pole design for synchronous machines that are excited by permanent magnets can be created easily. The high-pole version of a synchronous machine excited by a permanent magnet is characterised by short winding heads as well as by thin stator yokes. The result is a compact, space-saving construction.
The Siemens A&D HT-direct motors are designed for high availability. For example, the rare-earth magnets are dimensioned for multiple protection against demagnetisation. They are also made of a low-corrosive alloy and are additionally protected by a special coating. The long storage life of over 60,000 hours ensures long maintenance intervals and high availability values.
HT-direct high-performance torque motors can handle speeds of up to 800rpm and a torque range of up to 42kNm. This corresponds to an output of 2100kW. The low-voltage HT-direct motor, which has a solid shaft, is available either with air cooling in a grey cast iron housing or with water-jacket cooling in a steel housing. Sealing to IP55 is standard. The motors are designed for operation with frequency converters and, with the Sinamics devices from Siemens A&D, form an integral drive system with very high efficiency levels.