YOKOGAWA wt3000 User Manual

App-22 IM 760301-01E
RLC of AC Circuits
• Resistance
Current i when AC voltage of instantaneous value u = U
m
sinωt is applied to load
resistance R [Ω] is expressed by the equation below. I
m
denotes the maximum
current.
i =
Um
R
sinωt
=I
msinωt
If expressed using rms values, the equation is I = U/R.
There is no phase difference between a current flowing through a resistive circuit and
the voltage.
R
I
U
U
I
• Inductance
Current i when AC voltage of instantaneous value u = U
m
sinωt is applied to a coil load
of inductance L [H] is expressed by the equation below.
i =
Um
XL
sin ωt – sin ωt –
p
2
=
Im
p
2
If expressed using rms values, the equation is I = U/X
L
. X
L
is called inductive
reactance and is defined as X
L
= ωL. The unit is Ω.
Inductance works to counter current changes (increase or decrease), and causes the
current phase to lag the voltage.
L
I
U
U
I
π
2
• Capacity
Current i when AC voltage of instantaneous value u = U
m
sinωt is applied to a
capacitive load C [F] is expressed by the equation below.
i =
U m
X C
sin ωt + sin ωt +
π
2
=
I m
π
2
If expressed using rms values, the equation is I = U/X
C
. X
C
is called capacitive
reactance and is defined as X
C
= 1/ωC. The unit is Ω.
When the polarity of the voltage changes, the largest charging current of the same
polarity as the voltage flows through the capacitor. When the voltage decreases,
discharge current of opposite polarity as the voltage flows. Thus, the current phase
leads the voltage.
C
I
U
U
I
π
2
Appendix 4 Power Basics (Power, Harmonics, and RLC of AC Circuits)

YOKOGAWA wt3000 Specifications

General

Brand	YOKOGAWA
Model	wt3000
Category	Measuring Instruments
Language	English