Search

Premium Membership

Study specialized technical articles, papers & courses in low/high voltage areas. Save 50% on all courses with the Enterprise Plan.

Formulas

For a balanced star connected load with line voltage Vline and line current Iline:

Vstar = Vline / Ö3

Istar = Iline

Zstar = Vstar / Istar = Vline / Ö3Iline

Sstar = 3VstarIstar = Ö3VlineIline = Vline2 / Zstar = 3Iline2Zstar

For a balanced delta connected load with line voltage Vline and line current Iline:

Vdelta = Vline

Idelta = Iline / Ö3

Zdelta = Vdelta / Idelta = Ö3Vline / Iline

Sdelta = 3VdeltaIdelta = Ö3VlineIline = 3Vline2 / Zdelta = Iline2Zdelta

The apparent power S, active power P and reactive power Q are related by:

S2 = P2 + Q2

P = Scosf

Q = Ssinf

where cosf is the power factor and sinf is the reactive factor

Note that for equivalence between balanced star and delta connected loads:

Zdelta = 3Zstar

NOTATION
The symbol font is used for some notation and formulae. If the Greek symbols for alpha beta delta do not appear here [ a b d ] the symbol font needs to be installed for correct display of notation and formulae.
B
C
E
f
G
h
I
j
L
P
Q
susceptance
capacitance
voltage source
frequency
conductance
h-operator
current
j-operator
inductance
active power
reactive power
[siemens, S]
[farads, F]
[volts, V]
[hertz, Hz]
[siemens, S]
[1Ð120°]
[amps, A]
[1Ð90°]
[henrys, H]
[watts, W]
[VAreactive, VArs]
Q
R
S
t
V
W
X
Y
Z
f
w
quality factor
resistance
apparent power
time
voltage drop
energy
reactance
admittance
impedance
phase angle
angular frequency
[number]
[ohms, W]
[volt-amps, VA]
[seconds, s]
[volts, V]
[joules, J]
[ohms, W]
[siemens, S]
[ohms, W]
[degrees, °]
[rad/sec]

Premium Membership

Get access to premium HV/MV/LV technical articles, advanced electrical engineering guides, papers, and much more! It will help you to shape up your technical skills in your everyday life as an electrical engineer.
More Information

Leave a Comment

Tell us what you're thinking. We care about your opinion! Please keep in mind that comments are moderated and rel="nofollow" is in use. So, please do not use a spammy keyword or a domain as your name, or it will be deleted. Let's have a professional and meaningful conversation instead. Thanks for dropping by!

6  ×    =  six

Learn to Design Power Systems

Learn to design LV/MV/HV power systems through professional video courses. Lifetime access. Enjoy learning!

Subscribe to Newsletter

Subscribe to our Weekly Digest newsletter and receive free updates on new technical articles, video courses and electrical guides.