Regal Beloit is promoting its range of Marathon LT roller table motors, which are engineered to cope with the harshest operating environment found in steel-rolling mills. Further, the electrical design is very robust, enabling the motors to accommodate frequent instant drive reversals under load and to be able to sustain stall conditions for 20 minutes.
The LT motors are available in Frame sizes 100L to 315M, in 4, 6, 8, 10, 16 and 32 pole configurations. Ratings are 100kgm to 1000kgm and the safe stall time is certified to 20 minutes. The ability to create high-impulse torques has been built into the design for effective starting and reversing of large loads. Insulation is to Class F as standard, with an option to upgrade to Class H.
Modern steel-rolling tables are now almost always based on directly driven rollers, with each roller having its own motor, rather than all the rollers being driven by a large single motor through a chain or gear mechanism. The motors are expected to work very hard – usually 16–24 hours a day, seven days a week for many years – and typically, maintenance and servicing is undertaken only very occasionally. Therefore, the motors need to be robust, both mechanically and electrically, being of cast iron construction, with epoxy paint exterior and interior, and rated up to IP66. In addition, a rotating brass labyrinth shaft seal prevents water ingress at the shaft extension.
A typical working environment is likely to include high temperatures, high humidity and considerable amounts of dust. The Marathon LT roller table motors are fully enclosed to keep the dust at bay. They are naturally cooled, as the ventilation fan of a forced draught design may compromise long-term reliability. Instead, the cooling fins that aid heat dissipation are deep to increase the cooling surfaces and radial rather than longitudinal, so that dust cannot easily build up. Thermistors, thermostats or RTD temperature monitoring is also available.
The Marathon LT roller table motors have options for foot, flange and combined mounting, and the terminal box is designed for ease of use in the field. For further information, please visit www.rotor.co.uk.