Page 94 - Rotating Machinery Pratical Solutions to Unbalance and Misalignment

Rotating Machinery: Practical Solutions

0
330 30

300 60

270 90

240 120

210 150
180

Figure 5-19. Example (5.4) Determining the C and D Vectors

Measuring the length and angles of these vectors yields:

C = 5.6 mils @ 258 degrees.
D = 3.2 mils @ 24 degrees.

Step 6. Again additional values need to be calculated.
ab = (a × b) units @ (a + b) degrees = (.3 × .5) units @ (171 + 160)
ab = .2 units @ 331 degrees.

Note: The ab vector is expressed in units not in mils. This will
become clear further into this example.

Step 7. The next step is to use a new polar graph and plot a unity
vector UV. The unity vector will be one unit in length at zero (0)
degrees. This new plot should use a different scale from the other
plots, allowing the unity vector to be as large as practical. For this