There is no single motor size for a paddy line; the pre-cleaning screen, destoner, husker, whitener, polisher and elevators each carry a different load. The power and speed of every machine are taken from its own nameplate or from the old motor's label, and then husk dust and the operating hours over the season are taken into account.

DRG-132S-6 3 kW 1000 rpm cast iron frame DRG three-phase motor – paddy processing machine motor

Load behaviour by machine

  • Husker: The gap between the rubber rolls and the feed rate set the load. As the rolls wear the setting shifts, and the current drawn by the motor fluctuates with it.
  • Whitener and polisher: They work by friction in a stone or screen chamber; restarting with a full chamber is the hardest moment.
  • Elevator and screw conveyor: When the buckets or the screw trough stay full, the motor has to start under full load.
  • Screen and destoner: Usually low power, but the eccentric or vibrating mechanism wears the bearings and the foot fixings.

Husk dust and cooling

Husk is light and fibrous; it packs between the frame fins and weakens IC411 cooling, in other words heat removal by the air that the motor's own fan blows over the frame surface. IP55 protection limits dust getting inside the motor, but cleaning the build-up on the outside belongs in the plant's maintenance plan. If dust extraction is poor, motor temperature climbs. Where the area is classified as an explosive atmosphere because of dust density, a certified product is required; motors of that type are not part of the DRG standard range.

Speed and pulley calculation

Most paddy machines are belt driven. Machine shaft speed is found with n_machine = n_motor × D_motor / D_machine; a husker set up for a 1500 rpm motor cannot take a 3000 rpm motor without changing the pulleys. To check the ratio you can use the pulley and belt calculator.

Information to collect before ordering

  1. The power value on each machine's old motor label or machine nameplate
  2. Pulley diameters or coupling details, shaft diameter and length
  3. Foot or flange mounting and the shaft height
  4. Daily operating hours in season and whether the machine starts loaded

With this information you can compare the machines on your line with the examples on the agricultural machinery motors page and filter the right power by output and speed in the three-phase motor shop.