Recent content by fred2028

PF is P / S in general. If the transformer is running at 80.1% of full load, the PF should stay the same right since PF = 0.801P / 0.801S = P / S since if the transformer is running at 80.1% full load, the output S and output P would both be 80.1% right? So basically, no matter what load...

Question basically asks to find the parameters of a transformer via an open circuit and closed circuit test. We were taught that for OCT, V = (I * cos(theta)) * R V = (I * sin(theta)) * X To find the core losses. This makes sense, since we are only using the component of the current that...

Thanks, so in this case, the pumping would require more power than the amount of power the condenser and boiler would save? Thanks for the reply!

In a Rankine cycle such as a steam power plant, why does the liquid (water) have be condensed before being reheated first? Isn't the Q just extracted during the condensation stage, wasted into a nearby reservoir, and then re-added in the boiler? Could this water not be fed straight to the...

Oh, so what exactly does closed ckt test give you? R, or X? And open ckt? Thanks!

Does impedance not include resistance (Z = R + X)? I'm logically thinking that the closed circuit test gets the impedance because all of the I flows back to the source, and any resulting V drop would be due to the impedance (real and imaginary) in the transformer right? How about the open...

The questions in this pre-lab are pretty basic and conceptual, and have not yet been taught in class. However, I'd like to complete this prelab early since I will be busy later on. Because it is pretty conceptual, I don't have any attempt at them except Googling around. Quick explanations or...

OK thanks!

This is more of a concept question, so the template is not followed. Say you're given T(x,y,z) = xy-z And z = x+y Basically, T is a function of x, y, and z while z is a function of x and y. If we substitute z into T, would T become T(x, y) or stay T(x, y, z)?

I know that a 2nd order homo ordinary differential equation's solution is in the form of \[f(x) = {C_1}{e^{{a}t}} + {C_2}t{e^{{a}t}}\] for repeated real roots of the characteristic equation, and that the solution for a single complex root (and its conjugate) involves a cosine. I'm curious...

But the Heaviside function merely states that it equals a constant (1) when greater than t = a and another constant (0) when less, so can't you treat it like a constant?

Oh thanks! My mistake in LaTeX for the 3rd question. I meant \[f(t)u( - t + 1)u(t - 1)\] so it only turns on when t < -1 and t > 1 at the same time, which is never. Then the graph would just be a constant 0 right?

that depends on the value of a. This isn't the part I am confused about, it's been explained to me already. I need help with my last 2 questions.

This just means that when integrating a function times a Heaviside the Heaviside can be pulled out.

Oh OK thanks, that makes my life a lot easier in many situations. Could you shed some light on my last 2 questions? Thanks!