8 | SAMLEX AMERICA INC.
SAMLEX AMERICA INC. | 9
SECTION 2 |
General Information
2.1. DEFINITIONS
The following definitions are used in this manual for explaining various electrical
concepts, specifications and operations:
Peak Value:
It is the maximum value of electrical parameter like voltage / current.
RMS (Root Mean Square) Value:
It is a statistical average value of a quantity that varies
in value with respect to time. For example, a pure sine wave that alternates between
peak values of Positive 169.68V and Negative 169.68V has an RMS value of 120 VAC.
Also, for a pure sine wave, the RMS value = Peak value ÷ 1.414.
Voltage (V), Volts:
It is denoted by “V” and the unit is “Volts”. It is the electrical force
that drives electrical current (I) when connected to a load. It can be DC (Direct Current
– flow in one direction only) or AC (Alternating Current – direction of flow changes peri-
odically). The AC value shown in the specifications is the RMS (Root Mean Square) value.
Current (I), Amps, A:
It is denoted by “I” and the unit is Amperes – shown as “A”. It is
the flow of electrons through a conductor when a voltage (V) is applied across it.
Frequency (F), Hz:
It is a measure of the number of occurrences of a repeating event per
unit time. For example, cycles per second (or Hertz) in a sinusoidal voltage.
Efficiency, (
η
):
This is the ratio of Power Output ÷ Power Input.
Phase Angle, (
φ
):
It is denoted by “
φ
” and specifies the angle in degrees by which the
current vector leads or lags the voltage vector in a sinusoidal voltage. In a purely induc-
tive load, the current vector lags the voltage vector by Phase Angle (
φ
) = 90°. In a purely
capacitive load, the current vector leads the voltage vector by Phase Angle, (
φ
) = 90°. In
a purely resistive load, the current vector is in phase with the voltage vector and hence,
the Phase Angle, (
φ
) = 0°. In a load consisting of a combination of resistances, induct-
ances and capacitances, the Phase Angle (
φ
) of the net current vector will be > 0° < 90°
and may lag or lead the voltage vector.
Resistance (R), Ohm,
Ω
:
It is the property of a conductor that opposes the flow of cur-
rent when a voltage is applied across it. In a resistance, the current is in phase with the
voltage. It is denoted by "R" and its unit is "Ohm" - also denoted as "Ω".
Inductive Reactance (X
L
), Capacitive Reactance (X
C
) and Reactance (X):
Reactance is the
opposition of a circuit element to a change of electric current or voltage due to that
element's inductance or capacitance. Inductive Reactance (
X
L
) is the property of a coil
of wire in resisting any change of electric current through the coil. It is proportional to
frequency and inductance and causes the current vector to lag the voltage vector by
Phase Angle (
φ
) = 90°. Capacitive reactance (
X
C
) is the property of capacitive elements to
oppose changes in voltage.
X
C
is inversely proportional to the frequency and capacitance
and causes the current vector to lead the voltage vector by Phase Angle (
φ
) = 90°. The
unit of both
X
L
and
X
C
is "Ohm" - also denoted as "Ω". The effects of inductive reac-