The SC-542 Automatic Tension Controller meter as examines the parttake the tensity sensor, the magnetic powder brake or the magnetic powder coupling is the functional element, composes the permanent tensity control system. Receives, puts the volume material through the tensity sensor examination the tensity, carries on the comparison withthe hypothesis tensity value, thus the automatic control magnetic powder brake or the magnetic powder coupling excitation circuit maintains the volume material in to receive puts in the volume process the tensity to be constant. standard