1. The rotational speed of a pump shaft is 19.5 Hz. The frequency spectrum of accelerometers placed on inboard and outboard bearings in the vertical direction generally indicate shaft imbalance at a frequency of
A. 19.5 Hz.
B. 39 Hz.
C. 9.75 Hz.
D. Always a sub-synchronous value of shaft speed.
2.A ceiling fan has a rotational speed of 600 RPM and has five blades. The blade pass frequency at this speed is
A. 60 Hz.
B. 50 Hz.
C. 30 Hz.
D. 10 Hz.
3. The oil whirl phenomenon in a sleeve bearing (journal bearing), with a shaft frequency of fr , occurs approximately at the following frequency.
A. 0.45 x fr.
B. 1 x fr.
C. 2 x fr.
D. 2.45 x fr.
4. The coherence function between two detector signals is given by
A. 1/10.
B. ½.
C. 0.0
D. infinity.
5. The coherence function between two detector signals is given by
A. 1/10.
B. 2/11.
C. 0.0
D. infinity.
6. The rotational speed of a turbine shaft is 3600 RPM. A non-synchronous frequency of the shaft rotational speed is
A. 240 Hz.
B. 216 Hz.
C. 50 Hz.
7.The rotational speed of a turbine shaft is 3600 RPM. A sub-synchronous frequency of the shaft rotational speed is
A. 240 Hz.
B. 216 Hz.
C. 50 Hz.
8. The rotational speed of a turbine shaft is 3600 RPM. A harmonic frequency of the shaft rotational speed is
A. 240 Hz.
B. 216 Hz.
C. 50 Hz.
9. A shaft in a vibration testing equipment is supported by two bearings. The shaft imbalance generally shows up at the following frequency and accelerometer position
A. (2 x shaft speed, axial)
B. (1 x shaft speed, radial)
C. (2 x shaft speed, radial)
D. (1 x shaft speed, axial)
10. In a ball bearing (outer race fixed), the Ball Pass Frequency of the Outer race (BPFO) is
A. Greater than the fundamental train frequency
B. Less than the ball pass frequency of the inner race
C. Less than the ball spin frequency
D. All the above
11. The property of the basic component in an accelerometer that converts force into electrical current is called
A. Electro-magnetic effect
B. Electro-static effect
C. Piezo-electric effect
D. Piezo-acceleration effect
E. Piezo-magnetic effect
12. The frequency bandwidth of a high-quality piezo-electric accelerometer, with stud mounting on the bearing housing has the range
A. Less than 100 Hz.
B. Less than 1 kHz and is better than a hand-held accelerometer
C. Up to 20 kHz and is better than a hand-held accelerometer.
D. Up to 20 kHz, but is not as good as a magnetically mounted accelerometer