Page 92 - Rotating Machinery Pratical Solutions to Unbalance and Misalignment

Rotating Machinery: Practical Solutions

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90

e

b
b r
Y
c
a ▲
X

Figure 5-17. Determining the Vector Angle

Example (5.4) (Cont’d)

Step 4. Calculate the following additional vectors from the mea-
sured values. First, the measured values will be assigned new
names.
A = N0 > N1 = 6.3 mils @ 198 degrees.
Aa = F0 > F1 = 2.1 mils @ 7 degrees.
B = F0 > F2 = 7.1 mils @ 121 degrees.
Bb = N0 > N2 = 3.3 mils @ 281 degrees.
The following calculations are now performed:

a = (Aa/A) mils @ (Aa – A) degrees = (2.1/6.3) @ (7 – 198)
degrees.
a = .3 mils @ 171 degrees.

b = (Bb/B) mils @ (Bb – B) degrees = (3.3/7.1) @ (281 – 121)
degrees.

b = .5 mils @ 160 degrees.
Na = (N0 × a) mils @ (N0 + a) degrees = (7.1 × .3) mils @ (60
+ 171) degrees.

Na = 2.1 mils @ 231 degrees.