Starting Current Laminations

Owing to the large currents drawn when motors are started direct on line, it is necessary for some limitations to be imposed to avoid disturbances to the supply system. These disturbances not only cause an annoying flicker to lights, and problems with TV sets, but in extreme cases may cause sensitive relays to operate, or cause disruption to essential machinery or medical equipment.

Therefore, all supply authorities restrict the starting currents to a maximum allowable level, and the restrictions of all the larger authorities are calculated on a similar basis. The maximum currents are stated in supply authority regulations. Some variations do exist in rural areas and in special circumstances. Please check with your supply authority and refer to the Australian standard.

The starting current limitation leads us to consider the next aspect of this paper.