Formulas for unit 63

Question	Answer
Apparent Power	Voltage x current
Xl	2πfL
Xc	1/(2πfC)
STAR VOLTAGE	Vp=Vl/√3
STAR CURRENT	IP=IL
DELTA VOLTAGE	VP=VL
DELTA CURRENT	Il=Ipx√3
True Power	V x I x cos (Ө)
Watts in 1 horse power	746 watts
Temperature coefficient of resistance formula	R=R0(1+α(T1-T0))
Connections of an auto transformer	Image: 90770fe2-875b-47b7-8fd5-2b8f0cd9a079.gif (image/gif)
Slip speed of a motor	((Ns-Nr)/Ns) x 100
What are the benefit of a wound-rotor induction motor?	Reduced starting current Increased available torque Is good for large initial loads
How do you calculate stator speed?	NS=f/p (p= pairs of poles)
What is the resonant frequency?	When Xl=Xc
What is a high pass filter?	A filter that passes high frequencies but blocks low frequencies
What is a low pass filter?	A filter that blocks high frequencies but allows low frequency signals
What is the bandwidth of a circuit?	The difference between the half power points either side of the resonant frequency. Image: dec610b2-4d54-48bb-8c75-f77b25f7df5e.gif (image/gif)
Efficiency	Output/Input x 100

Resource summary

	Created by giannini.chambers about 10 years ago