Useful Formulas for Power System Analysis
& Power Factor Correction

Programs

Harmonic Analysis Program


Formula Symbols

C	Capacitance (farads)
fs	System Frequency
f	Frequency (Hertz)
I	Current (amps)
I1, I2	Currents of bank or stages being switched and of bank or stage already energized
Imax peak	A peak value calculated without damping. In practical circuits it will be about 90 percent of this value
Ih	RMS current (amps) at harmonic (h)
Kvar	Reactive Power (kvar)
kVAtx	Three-phase transformer rating
Ztx	Nameplate impedance (%)
kVAr	Three-phase capacitor bank rating
KVA	Total Power (kVA)
kV	kilovolts (kv)
KW	Real Power (kw)
Leq	Total equivalent inductance per phase between capacitor banks or stages, in microhenrys
PF	Power Factor (no unit)
P	Real Power (KW)
Q	Reactive Power (kvar)
S	Total Power (KVA)
Subscript I	Initial
Subscript d	Desired
Subscript	Three Phase
Subscript	Single Phase
Subscript LN	Line to Neutral
Subscript LL	Line to Line
Subscript SC	Short Circuit
Th	Single Frequency TIF at harmonic (h)
Vn	Harmonic Voltage magnitude
Vrms	Root mean square (rms) value of voltage
VLL	Rated maximum voltage in kilovolts
I rms	Root mean square (rms) value of current
Isc	Symmetrical rms short-circuit current, in amperes
Vpk	Peak magnitude
Xc	Capacitive Reactance (ohms)
XC	Capacitive reactance (W)
XL	Inductive reactance (W)
R	Resistance (W)
Xn	Filter inductor - reactance (W)
n	Harmonic at which filter is tuned
q	Power factor angle

A) Capacitors Connected in Parallel
B) Capacitors Connected in Series
C) Capacitive Reactance
D) Capacitance
E) Capacitor Kilovars
F) Power Factor
G) Kilovars Required to Change Power Factor
H) Equations for Total Power Factor
I) Total Power
J) Reactive Power
K) Voltage Rise
L) Released System Capacity for Power Factor Improvement
M) Loss Reduction for Correcting Power Factor
N) Capacitor Current
O) Total Harmonic Distortion
P) Root Mean Square, RMS
Q) Displacement Power Factor, DPF
R) Total Power Factor, TPF
S) Resonant Frequency, h
T) I*T Product
U) Quality Factor, Q
V) Crest Factor, CF
W) Inrush Current Calculation for Single Capacitor Bank Switching
X) Inrush Current Calculation for Back-To-Back Capacitor Bank Switching

Formulas

	A) Capacitors Connected in Parallel
	B) Capacitors Connected in Series
	C) Capacitive Reactance Xc
	D) Capacitance C
	E) Capacitive Kilovars
	F) Power Factor
	G) Kvars Required to Change Power Factor     where:  = Initial Power Factor Angle  = Final Power Factor Angle
	H) Equations for Total Power good for both 3 phase and single phase calculations
	I) Total Power
	J) Equations For Reactive Power
	K) Approximate Voltage Rise for Addition of Capacitors where:
	L) Released System Capacity for Power Factor Improvement
	M) % Loss Reduction for Correcting Power Factor
	N) Capacitor Current
	O) Total Harmonic Distortion
	P) Root Mean Square, RMS
	Q) Displacement Power Factor
	R) Total Power Factor, TPF
	S) Resonant Frequency
	T) I*T Product
	U) Quality Factor, Q
	V) Crest Factor, CF
	W) Inrush Current and Frequency Calculation for Single Capacitor Bank Switching
	X) Inrush Current and Frequency Calculation for Back-To-Back Capacitor Bank Switching

Northeast Power Systems, Inc.
66 Carey Road
Queensbury, New York 12804
Phone: 518-792-4776
Fax: 518-792-5767

        E-mail: sales@nepsi.com
        Website: http://www.nepsi.com/