Establishment of torque standards

Korea Research Institute of Standards and Science(KRISS) has developed a 100 Nm and a 2 kNm deadweight torque standard machines. The 100 Nm torque machine can generate torque from 0.1 Nm to 110 Nm. The length of its torque arm is 0.25 m for both sides. It uses continuous deadweight stack. At each side, it has three different deadweight stacks. By rotating the base plate on which the deadweight stacks are located, the machine can adjust a suitable deadweight stack of appropriate torque range. Its relative uncertainty is 5 × 10-4 from 0.1 Nm to 1 Nm and 5 × 10-5 from 1 Nm to 110 Nm. The 2 kNm deadweight torque machine uses a continuous deadweight stack at the left side and a binary type combination deadweight stack at the right side. By combining both deadweight stacks, the machine can generate torque from 10 Nm to 2200 Nm for both clockwise and counter-clockwise directions. The machine fixes its torque arm when changing the torque to maintain previous torque level. Its relative expanded uncertainty is 5 × 10-5