Why is three-phase power most often used by large HVACR equipment operators?
What will be an ideal response?
Individual line current for a three-phase load is approximately 58% of a similarly sized single-phase load. Since wire is sized by current draw, reducing the line current also reduces the wire size and voltage drop. There is less power loss to transformers in using it.
Three phase motors are smaller, less expensive, more reliable, and more efficient than single phase. They do not require special capacitors to increase their starting torque.
Some three phase motors have an ability to correct the phase shift caused by some other inductive loads. Large commercial consumers of electric power are often faced with a surcharge that is applied to their base electrical rate when their power consumption is out of phase. Three phase motors can reduce or eliminate this surcharge by correcting the phase angle.
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Goats were in America when the first settlers arrived
Indicate whether the statement is true or false
Which of the following statements is true?
A. The change in internal energy of an ideal gas can be calculated using the equation dU = CPdT, even if the pressure of the gas isn’t constant. B. The change in enthalpy of a supercritical fluid can be calculated using the equation dH = CPdT, even if the pressure of the fluid isn’t constant. C. The expression CP = CV + R was derived for ideal gases, but is frequently applied to liquids and solids as well. D. The properties tabulated in the steam tables are all state properties, but none of them are extensive properties. E. WEC = -PV, so U - WEC is equal to H.
If the base current increases, ________
A) the collector current increases and the emitter current increases B) the collector current increases and the emitter current decreases C) the collector current increases and the emitter current does not change D) the collector current decreases and the emitter current decreases
Considering the dimensions of a block face to be 15 5/8" long and 7 5/8" wide and assuming mortar joint width to be 5/16" for both bed joints and head joints, what is the length in inches of 5 block faces and 4 mortar joints?
What will be an ideal response?