Hi, My text isn't great - can anyone help me with the following question? A waveform is represented by the following equation: e = 100 sin 314,28 tDetermine: a) the maximum value of the emf b) the rms and average values c) the frequency of the suppy d) the instantaneous value of the emf @ 12 milliseconds after passsing through the zero positively e) the form factor Thanks
Your sinusoidal wave can be generically represented as: Comparing your equation with the generic equation you can equate the following: Rearrange to get the frequency f. Substitute the value 12e-3 for t in your orginal equation to get the instantaeous voltage. The form factor is calculated as: Have a go and post up you answers if you want someone here to check your calculations. Dave
Thanks Dave, I'm at work at the moment but I'll have a crack at it tonight and post my answers tomorrow.
a) from the generic equation Emax = 100 b) Erms = 1/1.4142 x 100 = 70.71 Eave = 2/3.1428 x 100 = 63.64 e) Form factor = 70.71/63.64 = 1.11 c) 314.28 = 2 x pi x f so f = 314.28/ 6.2856 = 50Hz What happens to the (t) from the generic equation (2 x pi x f x t)? d) I'm afraid you lost me here - I couldn't figure out where you got (12e - 3) from so I did my own thing... e @ 12 milliseconds = E(max) sin (2 x pi x f x t) = 100 sin (2 x 3.1428 x 50 x 0.012) = 100 sin (3.77136) = 100 x 0.065775 = 6.5775 Is this correct? Thanks.
Q: The starting circuit of a motor has a coil with a resistance of 40 Ohm and an inductance of 0,25 henry connected in series with a capacitor of 20 microfarad. The supply is 250V, 50 Hz. Calculate: 1.1) the inductive reactance 1.2) the capacitive reactance 1.3) the impedance 1.4) the supply current 1.5) the power factor 1.6) the phase angle