generator guide bearing indicate a shaft deflection of 0.006 inch at 30º from No. 1 rotor arm. The 0.006 inch is the magnitude of vibration amplitude and the 30º counterclockwise is the location (direction). Using a scale (such as one-fourth inch equals 0.001 inch), draw the deflection as a vector. The 0.006 inch at 30º has been scaled as vector OA. Point O is the tail of the vector and point A is the head. Note that the arrowhead always points in the direction that the vector Note that the term "graphical sum" has been stressed. Vectors cannot be added in the usual sense without complicating this discussion. Thus, 0.005 plus 0.006 equals 0.011 in ordinary addition; however, graphical vector addition yields:
0.005 /150º + 0.006 /30º = 0.0056 /82º
The notation 0.005 /150º describes a vector having magnitude 0.005 inch and in a direction 150º from some reference line or axis.