Series AC Circuits #1
What is the formula to calculate total resistance in series?
R1 + R2 + R3 + ...
add them up
What is the formula to calculate series inductive reactance?
XL1 + XL2 + XL3 + ...
What is the formula for resonance in an LC circuit
1/ {2 x pi x sqaure root of (L X C)}
Decreasing the resistance in a series RC circuit will have what affect on the circuit impedance?
Decrease it
What hazaroudous condition could be created in a series resonant RLC circuit?
Volt drop across the components can become extremely high
What is the formula to calculate total inductance in series?
L1 + L2 + L3 + ...
add them up
What is the formula to calculate capacitors in series?
1/C1 + 1/C2 + 1/C3 + ...
sum of reciprocals
True or false? A power diagram for an RC series circuit would show a lagging power factor.
False
A capacitor is connected in series with a coil so that the two reactances are equal. If the uF rating of the capacitor is increased, does the current in the circuit increase or decrease?
Decrease, since Z increases
A resistor is connected in series with a coil. If the ohmic value of the resistor is increased, what happens to the phase angle for the total circuit?
Decreases
What is the total capacitive reactance if you have 3 capacitors in series that each have a reactance of 25 ohms?
75 ohms
In a purely capacitive circuit, the reactive power is 500 VAR. What is the apparent power? No Resistors
500VA
A coil and a capacitor are connected in series with the following values: coil has a resistance of 35 ohms. The coil has an inductive reactance of 48 ohms. The capacitor has a capacitive reactance of 30 ohms. What is the net reactance of this circuit?
48-30 = 18 ohms of reatance at an angle of 90 degrees
If a coil and capacitor are connected in series across an AC supply, the maximum current flows when XL and XC have what relationship?
They are equal
If the supply frequency is increased, how does affect the inductive reactance of a coil?
Increases
What is the phase angle of capacitors Xc?
-90 degrees
What is the value of true power in a purely inductive circuit? No resistors
0 W
What is the impedance of an AC circuit that has a 470 ohm resistor connected in series with a 8.8uF capacitor across a 240V, 60 Hz source?
Xc = 301.43 ohms
Pythagoras -> Z = 558.35 ohms
If a coil and capacitor are connected in parallel across an AC supply, the minumum current flows when XL and XC have what relationship?
What two components are connected in series with the start winding of a single phase motor to improve starting torque?
Phase shift capacitor and centrifugal switch
What is Power Factor?
the ratio of resistance to impedance
R/Z
What is the phase relationship between voltage and current in a purely resistive circuit?
They are in phase
zero degrees
A coil and a capacitor are connected in series with the following values: coil has a resistance of 35 ohms. The coil has an inductive reactance of 48 ohms. The capacitor has a capacitive reactance of 30 ohms. What is the total impedance of this circuit?
48-30 = 18 ohms
39.35 angle of 27.16
R, Vr and Pt are drawn in the same position on the impedance, voltage and power triangles. True or false?
True
how to derive the formula
1/( 2 x pi x sqrt (LC))
1/2 x pi x f x c = 2 x pi x f x L and solve for f