Electrical current that flows in one direction, either positive or negative
Alternating Current
Electrical current that changes between positive and negative directions
Frequency
The number of waveform cycles in one second
Period
The time it takes a periodic waveform to complete one full cycle before it repeats
Peake
The maximum absolute value of a waveform
Peake-to-peake
A measure of the difference between positive and negative maximum values of a waveform
Root-Mean-Square (RMS) Value
A statistical parameter representing the ffective value of a waveform
Voltage Unbalance
The unbalance that occurs when the voltages of a three-phase power supply or the terminals of a three-phase load are not equal
Single Phasing
The complete loss of one phase on a three-phase power supply
Current Unbalance
The unbalance that occurs when current is not equal on the three power lines of a three-phase system
Phase Unbalance
The unbalance that occurs when three-phase power lines are more or less that 120 degrees out of phase
Harmonic
A waveform component at an integer multiple of the fundamental waveform frequency
Total Harmonic Distortion (THD)
The ratio of the sum of all harmonic components in a waveform to the fundamental frequency component
Resistive Load
A load that keeps voltage and current waveforms in phase
True Power
Is the product of in-phase voltage and current waveforms and produces useful work
Reactive Load
An AC load with inductive and/or capacitive elements that cause the current and voltage waveforms to become out of phase
Reactive Power
The product of out-of-phase voltage and current waveforms and results in no net power flow
Power Factor
The ratio of true power to apparent power and describes the displacement of voltage and current waveforms in AC circuits
Apparent Power
A combination of true and reactive power and is given in units of volt-amperes (VA)
Inverter
A device that converts DC power to AC power
Line-Commutated Inverter
An inverter whose switching devices are triggered by and external source
Self-Commutated Inverter
An inverter that can internally control the activation and duration of its switching
Rectifier
A device that converts AC power to DC power
Transformer
A device that transfers energy from one circuit to another through magnetic coupling
DC-DC converter
A device that changes DC power from one voltage to another
Maximum Power Point Tracker (MPPT)
A device or circuit that uses electronics to continually adjust the load on a PV device under changing temperature and irradiance conditions to keep it operating at its maximum power point
Inverter Efficiency
Is the effectiveness of an inverter at converting DC power to AC power