Vector Diagram | Three Phase Vector DiagramPublished on 24/2/2012 and last updated on 3/9/2018
Pickup Level of Actuating Signal: The value of actuating quantity (voltage or current) which is on threshold above which the relay initiates to be operated. If the value of actuating quantity is increased, the electromagnetic effect of the relay coil is increased and above a certain level of actuating quantity the moving mechanism of the relay just starts to move. Three phase electrical quantities can be represented by vector diagram. The diagram represent three phase quantities is known as three phase vector diagram.
Voltages of a three phase system is shown in the figure. Phase-Sequence of the vectors, represent voltages, is shown in the figure by an arrow. The term phase sequence is used to indicate the order in which vectors are placed in relation to one another for counter-clockwise rotation. In the figure here three, phase to neutral voltages, are rotating. That means they would reach their maximum positive values in the sequence first R, then Y and then B. This sequence is referred as positive sequence. This represents the normal healthy condition of system.