3.14 Resistive, Inductive And Capacitive Circuits Flashcards
Electrical circuits which contain capacitors and inductors are found to oppose?
Alternating current
What are the two types of reactance?
-capacitive
-inductive
In circuits with reactance, the AC voltage and AC current are found to be?
Out of phase with each other
What are LCR circuits?
Circuits that contain inductors, capacitors, and resistors
What is resistance sometimes called?
Real load
Why is resistance sometimes called ‘real load’?
To distinguish it from the imaginary load of a circuits reactance
What is reactive energy?
When energy is being pushed back and forth without being dissipated as heat by the inductor or doing any work
The induced voltage across the coil is at maximum when?
The rate of change of current is at a maximum
In a circuit with only inductive reactance how much does the current lag behind the voltage?
Quarter of a cycle or 90˚
How can you increase the inductive reactance?
-introduce an iron core to the coil
-increase the frequency
Does AC current flow through a capacitor?
No current flows through after thee initial pulse which charges the capacitor
What is reactance?
Opposes the flow of alternating current
What is reactive power?
The rate at which the reactive energy is transferred
The true power of the AC varies constantly between?
Zero and its maximum value
What are the units for true power?
Watt (W)
What are the units for an inductive reactance and a capacitive circuit?
Ohms
What is impedance in an AC circuit?
A combined measure of capacitive reactance and inductive reactance
What is the skin effect?
Where a higher current is observed to flow along the outside ‘skin’ of a wire than in its core
What causes the skin effect?
Eddy currents within the conducting wire itself
Effective resistances are between what constant values?
0Hz to approximately 1,000Hz
What is meant by impedance?
The measure of the opposition to AC in a circuit
What does impedance take into account?
Resistance and reactance of the circuit
What’s the difference between resistance and reactance?
Reactance still impedes current but no energy is dissipated
What is ‘lost’ current of a capacitor?
The small amount of current that flows between the plates of the capacitor
If a capacitor is said to have ‘lost’ current, what is the capacitor know as?
A capacitor with ‘loss’
If the inductance reactance is higher than the capacitive reactance, the circuit is said to be?
Inductive
If the capacitive reactance is higher than the inductive reactance, the circuit is said to be?
Mainly capacitive
What causes a power factor les than 1?
When theres a presence of an inductive reactance in a device or circuit
Real power is transferred to the?
Environment by the circuit or device
Reactive power is?
Stored and returned to the circuit later in the AC cycle
How are AC generators and transformers rated?
By their apparent power
What are the units for the power of AC generators and transformers?
Volt-ampere (VA)
