MMC Predictive & Preventive Maintenance 3

Question 1

Motor current signature analysis (MCSA) is primarily used to detect:

Accepted Answer

Mechanical faults such as broken rotor bars and bearing defects

Answer

MCSA analyzes current waveform signatures to identify mechanical anomalies like broken rotor bars, eccentricity, and bearing faults without physical contact.

Question 2

Which vibration frequency is generated by a rolling element bearing with a defective outer race?

Accepted Answer

Ball pass frequency outer race (BPFO)

Answer

A defect on the outer race produces impacts at the ball pass frequency outer race (BPFO), a calculable frequency based on bearing geometry and shaft speed.

Question 3

What is the key advantage of thermographic surveys conducted during peak electrical load conditions?

Accepted Answer

Thermal anomalies are more pronounced under higher current flow

Answer

Resistance-related heating (I²R losses) increases with current, making loose connections and overloaded components easier to detect at higher loads.

Question 4

A preventive maintenance program shows high PM compliance but equipment failures have not decreased. The most likely root cause is:

Accepted Answer

PM tasks are not matched to actual failure modes

Answer

If PM tasks do not address the dominant failure modes of the equipment, completing them on schedule will not reduce failure frequency.

Question 5

In oil analysis, a high total base number (TBN) depletion rate in engine oil indicates:

Accepted Answer

Acid neutralization capacity is being consumed rapidly, suggesting contamination

Answer

TBN measures the oil's remaining alkaline reserve to neutralize acids; rapid depletion signals acid production from combustion by-products or contamination.

(MMC) Maintenance Management Certification Practice Test

(MMC) Maintenance Management Certification Practice Test

MMC Predictive & Preventive Maintenance 3