Which of the following controls can optimize the operation of lighting systems?
According to the institute of Electrical and Electronic Engineers (IEEE) standard 519. "Recommended Practices and Requirements for Harmonic Control in Electrical Power Systems." the maximum total harmonic distortion (THD) for general low voltage systems less than 600 votts) should be:
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A 25-kW motor, at full load, drives a centrifugal fan that produces 160,000 liters per second (l/s) of ventilation air. If the fan speed is reduced to a flow rate of 150,000 l/s, what is the new load on the motor?
A gas-fired boiler is operating with 31.9% excess air. A feedwater economizer is used to reduce the stack temperature rise from 310°C to 160°C. Using the natural gas combustion efficiency tables in your workbook, find the energy savings from the economizer as a percentage of historical fuel consumption.
Which type of lighting control technique operates in "manual on" and "auto-off mode, and can be used in situations where there is brief occupancy that do not need lights on?
A controller has a signal output that can range from 4 to 20 mA (milli-amperes). The controller regulates the output temperature from a three-way mixing valve from 5°C to 15°C. What is the control gain?
Which electric rate tariff would best cost justify a thermal energy storage (TES) system?
What is the uniform series present worth factor (P/A, i%, n) for an annual interest rate of 15% and a lifetime of 20 years?
A hot-water boiler has a cut-in set point of 65°C on the hot water supply temperature and a differential set point of 10°C. What is the hot-water supply temperature that causes the boiler to turn off?
TESTED 19 Apr 2025
