obtain the rotational losses of a universal motor if you are only given the impedance, RPM, voltage,poles, frequency, current and pf? Basically I need to solve for the shaft torque and efficiency but can't get my Pout value without the rotational losses. I've already solved for the Power Developed but need the rotational loss to get my Pout. Here are the parameters: 110V, 60 Hz, 2 pole, operating at 12,500 RPM at full load and draws a current of 5A at pf .74 lagging. Rs = .5 ohms, Xs = 2.235, Ra = 5.2, Xa = 12.563.