Electrical Systems & Power Quality Flashcards
7 cards from real EMP practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Electrical Systems & Power Quality flashcards as text
What is the primary benefit of implementing power factor correction in an industrial facility?
Answer: It reduces reactive power demand from the utility, improving system efficiency and lowering utility charges
Power factor correction reduces the reactive power demand from the utility, which improves the efficiency of the electrical distribution system and can eliminate or reduce power factor penalty charges on utility bills.
What does 'peak shaving' refer to in the context of facility energy management?
Answer: Reducing recorded peak demand by discharging stored energy or curtailing loads during high-demand periods
Peak shaving reduces the peak demand recorded by the utility by discharging stored energy (batteries, thermal storage, etc.) or temporarily curtailing non-critical loads during high-demand periods.
What transformer winding configuration is most commonly used in US commercial and industrial facilities to step down medium voltage to utilization voltage?
Answer: Delta-Wye with grounded neutral on the secondary
The Delta-Wye configuration with a grounded secondary neutral is the predominant choice in US commercial and industrial distribution because it provides a stable neutral reference, isolates primary from secondary, and supports ground fault protection.
What is the 'demand interval' as used in utility metering and billing?
Answer: The time window (typically 15 or 30 minutes) over which average power is measured to determine peak demand for billing
The demand interval is the measurement window—typically 15 or 30 minutes—during which the utility meter averages power consumption to calculate the peak demand value used for demand charge billing.
Which of the following best describes an advantage of advanced metering infrastructure (smart meters) for facility energy management?
Answer: Smart meters enable real-time energy monitoring and provide interval-based time-of-use consumption data
Smart meters transmit interval-based (typically 15-minute) consumption data in near real time, allowing energy managers to analyze usage patterns, respond to time-of-use rates, and identify anomalies promptly.
What is the primary purpose of an Uninterruptible Power Supply (UPS) system in a critical facility?
Answer: To provide seamless backup power during utility outages and condition power to protect sensitive equipment from power quality disturbances
A UPS provides instant backup power when utility power fails and also conditions the power supply by filtering surges, sags, and harmonics, protecting sensitive equipment from power quality disturbances.
What is a 'ratchet clause' in a utility rate schedule, and why is it significant for energy managers?
Answer: A billing mechanism where a single high peak demand event can set minimum demand charges for 11 to 12 subsequent months
A ratchet clause stipulates that monthly demand charges must be at least a specified percentage (e.g., 80%) of the highest peak demand recorded in the previous 11–12 months, meaning one unusually high peak can inflate bills for a full year.