Definitions - Samlexpower Evolution Series Owner's Manual

SECTION 1.2 |

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 periodically). 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 inductive 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, inductances 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 current 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 ), Capacitive Reactance (X ) and Reactance (X): Reactance is the opposition of a
L C
circuit element to a change of electric current or voltage due to that element's inductance or capacitance. Inductive
Reactance (X ) is the property of a coil of wire in resisting any change of electric current through the coil. It is
L
proportional to frequency and inductance and causes the current vector to lag the voltage vector by Phase Angle
(φ) = 90°. Capacitive reactance (X ) is the property of capacitive elements to oppose changes in voltage. X is
C C
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 and X
is "Ohm" - also denoted as "Ω". The effects of inductive
L C
reactance X to cause the current to lag the voltage by 90° and that of the capacitive reactance X to cause the
L C
current to lead the voltage by 90° are exactly opposite and the net effect is a tendency to cancel each other.
Hence, in a circuit containing both inductances and capacitances, the net Reactance (X) will be equal to the
difference between the values of the inductive and capacitive reactances. The net Reactance (X) will be inductive
if X > X and capacitive if X > X .
L C C L
SAMLEX AMERICA INC. | 9