Mixed Circuits Electrical Power Principles of Engineering Review

Mixed Circuits & Electrical Power Principles of Engineering

Review • • IT + VR 1 IT - IR 1 + VT - IR 2 IR 3 RT VR 3 + VR 2 - + + + IR 2 VR 1 VT + VR 2 - - IR 3 + VR 3 - - 2 RT

Mixed Circuit • Combine Elements & Simplify

Mixed Circuit •

Mixed Circuit •

Solve Components • Find V 1 • V= IR . 67 A 6. 67 V • Find V 2 • V 2=10 V-V 1 = 3. 33 V • Find I 2 • I 2=V 2/R 2 =. 33 A • Find I 3 • I 3= V 3/R 3

Ohm’s Law Chart Cover the quantity that is unknown. V I R Solve for V V=IR

Electrical Power Electrical power is directly related to the amount of current and voltage within a system. Power is measured in watts

Power Derivations •

Electrical Power Measurements • Power = Watt • 1 Watt = 1 VA (Electrical) • 1 Watt = 1 Joule/Sec (mechanical rate of doing work) • Energy is cannot be created or destroyed, only transformed

Direct Current • Direct Current (DC) • Voltage is constant polarity • Current Flow is one direction

Alternating Current • Alternating Current (AC) • Voltage Polarity is sinusoidal • Current flow oscillates

Where is it used? • DC • • • AC Cars Electronics & Computers Small motors Battery powered things • Power Distribution • Larger appliances • Big motors

Why AC • Transformation • Not that kind…but this • Electrical Transformers • Step Voltage up or down • Require AC waveform • POWER DOESN’T CHANGE • V then I

Remember Distribution 115, 000 Watts on 1Ω wire 1150 V*100 A = 115, 000 Watts on 1Ω wire 115, 000 V*1 A = 115, 000 Watts • Power lost to resistance • Plost = I 2 R • Plost = 100 A 21Ω =10, 000 Watts • Efficiency = 91% • Plost = I 2 R • Plost = 121Ω=1 Watt • Efficiency = 99. 1%