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What is the equation for inductive reactance? XL |
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What is the equation for capacitive reactance? |
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| Describe the relationship between voltage and current in an inductuve circuit. |
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Voltage leads current by 90 degrees in an inductive circuit. (ELI the ICE-man) |
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| What is the equation for impedance in and R-L circuit. |
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What is the equation for resonance frequency? (Fres) |
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What is the equation for impedance in a series R-C-L circuit? |
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What is the equation for impedance for a parallel R-C-L circuit? |
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Definition
ZT=VT/IT IT=√(IR2+(IL-IC)2) |
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| Given a parallel R-C-L circuit at resonance, DESCRIBE the net reactance of the circuit. |
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Definition
| Net Reactance (X) is at zero and the series resistance of the circuit determines circuit current output. |
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| Describe the characteristics of inductors when they are placed in and AC circuit. |
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| Because of a constantly changing current, a constantly changing EMF is produced. Becuase this EMF flows in a direction opposite the normal current it is measured in ohms.The value of the self induced EMF varies as a sine wave and lags the current by 900. |
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| 19. Given a parallel R-C-L circuit at resonance, DESCRIBE the circuit output relative to current. |
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Definition
| Net Reactance (X) is at MAXIMUM and circuit current output is minimum. |
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Given an AC single-phase or three-phase circuit, describe the characteristics of the power generated in the circuit. |
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Definition
AC power components are not in phase and as a result not all power can be used to perform work. Reactive power must be considered and removes some of the apparent power. The remaining power is true power and is the only component that may be used in real work. |
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- Describe the relationship between apparent, true (real), and reactive power using a power triangle.
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Apparent power (generator output) is the hypotenuses. True power (WATTS) is adjacent to the hypotenuse and forms angle θ. Reactive power (VARS) is the opposite angle from |
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| Define leading power factor |
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Power factor associated with capacitive circuits (ice man in eli the ice man) |
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| Define lagging power factor. |
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Power factor associated with inductive circuits |
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- State the reason three phase systems are used in the industry.
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Definition
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- Three-phase circuits weigh less than single-phase circuits of the same power rating.
- They have a wide range of voltages and can be used for single-phase loads.
- Three-phase equipment is smaller in size, weighs less, and is more efficient than single-phase equipment.
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| What is the equation for true power? |
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What is the equation for reactive power? |
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| What is the equation for apparant power? |
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| What is the equation for power factor? |
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| State the indications of an unbalanced load in a three-phase power system |
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Unbalanced three-phase circuits are indicated by abnormally high currents in one or more of the phases |
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