Mixed Deck — All CMRT Topics Flashcards

A technician is completing corrective maintenance on a 480V motor control center bucket. Before closing the compartment door and re-energizing, the FINAL verification step should be:

Answer: Confirm all tools are removed, connections are torqued to spec, and the compartment is clear of foreign material

Foreign material intrusion (tools, hardware, wire scraps) inside energized switchgear is a leading cause of arc flash events and equipment damage.

What is 'over-greasing' a bearing and why is it harmful?

Answer: Applying excessive grease that causes elevated temperatures, churning, and premature bearing failure

Over-greasing packs the bearing housing with excess grease, causing the rolling elements to churn the lubricant, generating heat, and ultimately leading to premature bearing failure.

Ferrography (analytical ferrography) in oil analysis provides information that routine spectroscopy does NOT, specifically by:

Answer: Allowing visual examination of wear particle morphology and size

Analytical ferrography separates and deposits wear particles on a substrate for microscopic examination, revealing particle shape, size, and surface features that identify the wear mechanism.

What is a key concept in equipment reliability?

Answer: Routine checks and early detection

A key concept in fostering equipment reliability is the systematic execution of routine checks and the ability to detect issues early. Through consistent inspections and condition monitoring, potential problems can be identified and addressed in their initial stages. This proactive maintenance strategy is fundamental to minimizing unexpected downtime, optimizing asset performance, and reducing overall operational costs.

When establishing PdM inspection route frequencies, the primary factor that should drive how often a machine is monitored is:

Answer: The P-F interval (time between a detectable fault and functional failure)

The P-F interval defines the detection window available; inspection frequency must be set at no more than half the P-F interval to reliably catch faults before functional failure.

Which measure describes the probability that a failed system will be restored to operating condition within a specified time?

Answer: Maintainability

Maintainability is the probability that a failed item will be restored to a specified condition within a given time when maintenance is performed.

Infrared thermography on an indoor low-voltage switchgear panel is most effective at identifying which type of defect?

Answer: Loose or corroded electrical connections causing resistive heating

Loose or corroded connections increase contact resistance; IR thermography detects the resulting heat signature before the connection fails, making it the primary electrical PdM tool for connection integrity.

What is the primary goal of maintenance practices?

Answer: To extend equipment life and reliability

The primary goal of maintenance practices is to extend the operational life and enhance the reliability of equipment. By performing regular inspections, servicing, and repairs, maintenance prevents unexpected breakdowns and ensures machinery functions optimally. This approach minimizes downtime, reduces repair costs, and maximizes productivity.

The MAIN purpose of a post-repair functional test before returning equipment to service is to:

Answer: Confirm the equipment operates within its designed specifications after the repair

A functional test verifies that the corrective repair resolved the failure mode and that the equipment meets its required performance parameters before operators depend on it.

When performing laser shaft alignment, an angular misalignment condition is corrected by:

Answer: Adding or removing shims under the feet to change the shaft angle

Angular misalignment (shaft centerlines not parallel) is corrected by shimming under the feet of the moveable machine to change the shaft's angle relative to the driver.

During corrective maintenance documentation, a technician should record 'as-found' conditions BEFORE making any repairs because:

Answer: As-found data provides the baseline for root cause analysis and prevents recurrence

As-found measurements and observations capture the failure state needed to identify root causes and implement changes that prevent the same failure from recurring.

Resonance in a mechanical structure is most likely to occur when:

Answer: A forcing frequency coincides with the structure's natural frequency

Resonance is a condition where an external forcing frequency matches the natural (resonant) frequency of the structure, causing amplified vibration response.

What is the purpose of 'maintenance kitting' in a planned work order?

Answer: Packaging all required parts and materials at the storeroom before the job starts so technicians do not waste time searching for materials

Kitting pre-stages all parts, consumables, and materials for a specific job so that when the technician arrives, everything needed is ready, eliminating travel and search time.

A corrective maintenance work order is typically initiated when:

Answer: Equipment fails or its performance drops below acceptable standards

Corrective maintenance is triggered by an actual failure event or a detected degradation that renders the equipment unable to meet its required function.

What is a key concept in equipment reliability?

Answer: Routine checks and early detection

To maintain high equipment reliability, routine checks and early detection are indispensable. Consistent monitoring of equipment health through scheduled inspections and condition-based techniques enables the identification of potential failures at their nascent stages. This proactive intervention prevents catastrophic breakdowns, reduces repair complexity, and ensures continuous, efficient operation.

What is a key concept in troubleshooting and analysis?

Answer: Routine checks and early detection

In troubleshooting and analysis, routine checks and early detection are crucial for identifying the root cause of problems efficiently. By regularly monitoring system performance and detecting anomalies early, technicians can pinpoint issues before they become complex failures. This proactive approach streamlines the diagnostic process, reduces repair time, and prevents recurrence.

Schedule compliance (also called schedule adherence) is a KPI that measures which of the following?

Answer: The percentage of work orders completed on the day they were scheduled

Schedule compliance measures the percentage of scheduled work orders that were completed on the planned date, indicating how well the maintenance organization follows its plans.

Which root cause analysis tool uses a series of 'why' questions to drill down to the underlying cause of an equipment failure?

Answer: 5 Whys analysis

The 5 Whys technique iteratively asks 'why' until the physical, human, and latent root causes of a failure are identified.

What does 'interference fit' (press fit) mean when installing a bearing or coupling hub on a shaft?

Answer: The hub or bearing bore is slightly smaller than the shaft diameter, requiring force or heating to assemble

An interference fit (press fit) means the bore is smaller than the shaft diameter so the component must be pressed or thermally expanded for installation, creating a tight grip that transmits loads without slipping.

The Ball Pass Frequency Outer Race (BPFO) bearing defect frequency is determined by which set of parameters?

Answer: Number of rolling elements, shaft speed, and contact angle

BPFO = (N/2) × shaft speed × (1 − (Bd/Pd) × cos α), where N is the number of rolling elements, Bd is ball diameter, Pd is pitch diameter, and α is the contact angle.