What is the total power factor of two single-phase motors connected in parallel, each with specific power ratings and power factors?
The total power factor of two single-phase motors connected in parallel, with given specifications, is calculated to be 0.84 lagging.
Calculation of Total Power Factor
Explanation: Firstly, let's determine the true power consumed by both the motors. The true power can be calculated using the formula: P = HP * 746/efficiency. For Motor A: PA = 0.25 * 746 / 0.60 = 311.67 Watts. For Motor B: PB = 0.5 * 746 / 0.70 = 533.14 Watts. Next, we calculate the apparent power using the formula: S = P / pf. For Motor A: SA = 311.67 / 0.70 = 445.24 VA. For Motor B: SB = 533.14 / 0.95 = 561.2 VA. The combined apparent power when the loads are connected in parallel is the summation of the individual apparent powers: S = SA + SB = 445.24 + 561.2 = 1006.44 VA. Similarly, the total real power is P = PA + PB = 311.67 + 533.14 = 844.81 Watts. Finally, the power factor, defined as the ratio of real power to apparent power, for the combination would be: PF = P/S = 844.81/1006.44 = 0.84 lagging.