You are an electrician working in an industrial plant. You are building a motor

Question

You are an electrician working in an industrial plant. You are building a motor control cabinet that contains six motor starters and six pilot lamps. All control components operate on 120 volts AC. Two of the motor starters have coil currents of 0.1 amperes each and four have coil currents of 0.18 amperes each. The six pilot lamps are rated at 5 watts each. The supply room has control transformers with the following rating (in volt-amperes): 75, 100, 150, 250, 300, and 500. Which of the available control transformers should you choose to supply the power for all the control components in the cabinet? (Choose the smallest size that will supply the power needed.)

Explanation / Answer

Power for 2 motors with 0.1A
P=2*120*0.1=24W
Power for 4motors with 0.18A
P==4*120*0.18=86.4W
power for 6 pilot lamps is 5W
so total power in watts P=24+86.4+5=115.4W
consider power factor to be 0.95
VA of transformer =PF*power in watts =115.4*0.9=109.63VA

so it is better to consider transformer with 150VA

Related Questions

Navigate

• Browse (All)
• Browse Y
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.