Deck 8: Ac Parallel Circuits

Question 1

Before the power factor of a motor can be corrected, what must be determined first?

Answer 1

Before the power factor of a motor can be corrected, it must first be determined how much out of phase current and voltage are with each other.

Question 2

In ____________________ circuits, the current triangle is divided by the reference vector V to obtain the impedance triangle.

Answer 2

parallel

Question 3

What are two important differences between series and parallel circuits, which can be seen by looking at the magnitudes of the currents and impedances?

Answer 3

1. The current is at a maximum in a series resonant circuit and at a minimum in a parallel resonant circuit.
2. The impedance is at a minimum in a series resonant circuit and at a maximum in a parallel resonant circuit. These factors make parallel resonance a useful feature in tuned circuits.

Question 4

In ____________________ circuits, the voltage triangle is divided and multiplied by current to obtain the impedance and power triangles, respectively.

Question 5

How do we know that a voltage vector is a reference vector?

Question 6

The power factor of the circuit is found by the use of the expression: PF = P + VI.

Question 7

The amount of reactive power or VARs (volt-amperes-reactive) can be determined using the formula: VARs = P/VA.

Question 8

The voltage across any branch circuit in a parallel arrangement is the same as the ____________________ voltage.

Question 9

Before you can calculate the amount of capacitance that is needed, what must you first determine?

Question 10

In a series circuit at the ____________________ point, the effects of inductive reactance and capacitive reactance cancel each other.

Question 11

What are the advantages of unity power factor?

Question 12

Nearly all commercial, industrial, and residential power circuits are connected in parallel.

Question 13

The apparent power or volt-amperes of the circuit can be determined by multiplying the applied voltage by the total current.

Question 14

The current in a series circuit reaches its maximum value at ____________________.

Question 15

The total (line) current for an ac parallel circuit may not be equal to the arithmetic sum of the current in each of the branch circuits.