Delmar’s Standard Textbook of Electricity 7th. Edition by Stephen L. Herman | 9781420093568 | 1337900346

Basic Electrical

Delmar’s Standard Textbook of Electricity

2 SOLVED PROBLEMS

104 SOLVED PROBLEMS

Question: 11.2

Can Type THHN insulation be used in wet locations? ...

Verified Answer:

Locate Type THHN insulation in the second column. ...

Question: 21.3

An AC oil-filled capacitor has a voltage rating of 300 WVDC. Will the voltage rating of the capacitor be exceeded if the capacitor is connected to a 240-V, 60-Hz line? ...

Verified Answer:

The DC voltage rating of the capacitor indicates t...

Question: 18.2

In this circuit, one resistor is connected in parallel with two inductors (Figure 18–12). The frequency is 60 Hz. The circuit has an apparent power of 6120 VA, the resistor has a resistance of 45 Ω, the first inductor has an inductive reactance of 40 Ω, and the second inductor has an inductive ...

Verified Answer:

Impedance Before it is possible to calculate the i...

Question: 8.2

Both of the preceding circuits were solved by first determining which parts of the circuit were in series and which were in parallel. The circuits were then reduced to a simple series or parallel circuit. This same procedure can be used for any combination circuit. The circuit shown in Figure 8–9 ...

Verified Answer:

The first step is to reduce the top part of the ci...

Question: 20.4

Three capacitors with values of 10 μF, 30 μF, and 15 μF are connected in series to a 480-V, 60-Hz line (Figure 20–11). Find the following circuit values: XC1—capacitive reactance of the first capacitor XC2—capacitive reactance of the second capacitor XC3—capacitive reactance of the third capacitor ...

Verified Answer:

Because the frequency and the capacitance of each ...

Question: 20.5

Three capacitors having values of 50 μF, 75 μF, and 20 μF are connected in parallel to a 60-Hz line. The circuit has a total reactive power of 787.08 VARs (Figure 20–14). Find the following unknown values:XC1—capacitive reactance of the first capacitor XC2—capacitive reactance of the second capacit ...

Verified Answer:

Because the frequency of the circuit and the capac...

Question: 8.1

Solve the combination circuit shown in Figure 8–5. ...

Verified Answer:

The first step in finding the missing values is to...

Question: 7.3

In the circuit shown in Figure 7–19, three resistors are connected in parallel. Resistor R1 is producing 0.075 W of heat, R2 is producing 0.45 W of heat, and R3 is producing 0.225 W of heat. The circuit has a total current of 0.05 A. ...

Verified Answer:

Because the amount of power dissipated by each res...

Question: 7.2

In the circuit shown in Figure 7–15, three resistors are connected in parallel. Two of the resistors have values of 900 Ω and 1800 Ω. The value of Resistor R2 is unknown. The total resistance of the circuit is 300 Ω. Resistor R2 has a current flow of 0.2 A. Find the missing circuit values. ...

Verified Answer:

The first step in solving this problem is to find ...

Question: 32.4

A 15-hp three-phase motor is connected to 480 volts. The motor has a locked rotor code J. What is the approximate starting current for this motor? ...

Verified Answer:

The chart in Figure 32–42 lists that the approxima...

Question: 32.3

An 800-hp, three-phase squirrel-cage motor is connected to 2300 V. The motor has a code letter of J. What is the starting current of this motor? ...

Verified Answer:

Table 430.7(B) of the NEC gives a value of 7.1 to ...

Question: 10.15

Determine the ohms-per-mil foot at 75°C for a copper conductor. ...

Verified Answer:

Use the formula

{\mathsf{R}}={\mathsf{R}}_{...