Deck 11: Power Factor

Question 1

Why are capacitors useful in power factor correction?

Answer 1

It is common practice in many industrial installations to use banks of capacitors for power factor correction. A capacitor is a device that has a leading current and, therefore, a leading power factor. When capacitors are connected in a circuit with inductors, the leading VARs of the capacitors act to cancel the lagging VARs of the inductors. In this way, power factor can be corrected.

Question 2

The is a rotating electrical machine that has no electrical or mechanical loads connected to it.

A) synchronous motor
B) dc motor
C) ac generator
D) synchronous condenser

Answer 2

D

Question 3

A dielectric test set must be used while testing capacitors. This device is often referred to as a because of its ability to produce a high voltage or high potential.

A) DIVOLT
B) DIPOT
C) HIPOT
D) HIVOLT

Answer 3

C

Question 4

A pure element causes the voltage and current to be in-phase with each other.

A) conductive
B) resistive
C) inductive
D) capacitive

Question 5

Most capacitors used in industry, especially for power factor correction, are called capacitors.

A) conducting
B) dc
C) polarized
D) nonpolarized

Question 6

When current begins to flow through a(n) , a magnetic field expands around the .

A) conductor
B) resistor
C) inductor
D) capacitor

Question 7

When testing capacitors, how is an ohmmeter used?

Question 8

Assume that an inductor has an inductive reactance of 100 ohms and the wire has a resistance of 10 ohms. What is the impedance?

A) 10.5
B) 100.5
C) 110
D) 1000

Question 9

When two parallel feeders are installed to each of the synchronous condensers, the conductors can be sized for the value of the required ampacity.

A) one-quarter
B) half
C) double
D) four times

Question 10

In a three-phase circuit, the apparent power can be computed using this formula: VA = volts times times the square root of three.

A) amps
B) resistance
C) inductance
D) capacitance

Question 11

A capacitor does not require a separate disconnect means if it is connected to the side of the motor overload protective device.

A) switch
B) fuse
C) starter
D) load

Question 12

Apparent power is generally called .

A) volt amps
B) current voltage
C) circuit current
D) capacitance

Question 13

When the power factor of the plant is 1.0 (unity), the kilovarmeter reads .

A) 0
B) 50
C) 100
D) infinity

Question 14

Conductors in capacitor circuits must be rated no less than percent of the current rating of the capacitor.

A) 90
B) 100
C) 120
D) 135

Question 15

When testing capacitors, if the capacitor is good, the microammeter should indicate current.

A) zero
B) high
C) low
D) oscillating

Question 16

In a pure inductive load the current will lag the voltage by degrees.

A) 45
B) 60
C) 90
D) 180

Question 17

What rules apply when you are using parallel feeders?

Question 18

How can you determine the power factor of a system?

Question 19

The amount of capacitance needed can be determined by connecting a(n) , ammeter, and voltmeter to the circuit.

A) coulometer
B) megohmmeter
C) wattmeter
D) ohmmeter