Power Quality Analysis Glossary - Power Quality Analysis Real Power (P)
Real power is the power generated if a voltage is placed over a purely resistive load and current is allowed to flow. This is also called active power and is usu- ally measured in watts (W) or kilowatts (kW).
Energy
Energy is the generation or use of elec- tric power over a period of time. This is usually expressed in kilowatt-hours (kWh).
Reactive Power (Q) Reactive power is the power that is generated by reactive components (e.g. inductors, capacitors) to create a mag- netic field. This is usually measured in Volt-Ampers reactive (VAr).
Apparent Power (S)
Apparent power is the perceived power from a load that has both resistive and reactive components. Apparent power is the vector sum of both real and reactive power and is usually measured in Volt- Amperes (VA).
Power Factor
Power factor is a measure of a power system’s efficiency and is the ratio of real power (Watts) to apparent power (Volt-Amperes).
Fundamental frequency
The fundamental frequency is the low- est and most predominant frequency in a power system (e.g. the fundamental frequency of the mains voltage in the EU is 50 Hz). The fundamental frequency is also called the first harmonic of the sys- tem.
Harmonics Harmonics are a integer frequency mul- tiplication of the fundamental frequency (e.g. with a fundamental of 50 Hz, the 2nd harmonic is 50 x 2 = 100 Hz, 3rd
harmonic
is 50 x 3 = 150 Hz). Harmonics can be in the form of current harmonics or voltage harmonics and can be caused by a vari-
4. 2 Inrush current
As a motor begins the current needed to start the motor can be 10 to 15 times the normal operating current. This initial surge of current can cause dips in volt- age and can be hard to analyse with nor- mal test instruments, for this reason an analyser with a fast logging function is required.
Flickers
Defined by the IEEE std 59 “Flicker is the impression of unsteadiness of visual sensation induced by a light stimulus whose luminance or spectral distribution fluctuates with time”. It is thus a notice- able and repeated dip or change in volt- age of a power system. This has many causes and many results including the surges in motors, problems to people with epilepsy, unpredicted responses of electronic circuits and displays to flicker.
ety of modern day equipment including resonating transformers, switch-mode power supplies, IT equipment, etc. Har- monics can cause a variety of system problems including overheating, false tripping of protective devices, excessive current draw and power fluctuations.
Interharmonics
Interharmonics are harmonics that are not an integer multiplication of the fun- damental frequency. The main sources of interharmonic waveform distortion are static frequency converters, induc- tion motors and arcing devices.
Total Harmonic Distortion (THD) This is the ratio of a wave’s harmonic content (for voltage or current) to its fundamental component. Note: this is expressed as a percentage and is also called the “harmonic factor”.
Transients
A transient is a short surge of current or voltage, which often occurring before steady-state conditions have become established.
Part No.
INPUTS
Number of current measuring inputs Number of voltage measuring inputs MEASUREMENTS
TRMS Current measurement (Min., Max., Avg.) TRMS Voltage measurement (Min., Max., Avg.) Scope function
On-line harmonics measurement Frequency measurement Power measurement (W, VA, VAr) THD and harmonics analysis Interharmonics analysis Power Factor and cos ϕ
Registration of voltage events (sags, swells, interruptions)
Statistical evaluation Current in neutral conductor Phase diagram Unbalance
EN 50160 Analysis Flicker measurement Transients measurement
Waveform recording Inrush currents
Energy measurement Signalling Temperature measurement Integration period COMMUNICATION PORTS USB
RS232
GPS time sinhronisation Remote instruments control GENERAL
Graphical LCD with backlight On-site analysis of recorded data Built-in power supply for flexible clamps Maximal recording time Memory module size PC Sofware
Maximal test voltage – interphase value Maximal test voltage – between phase and PE conductors Frequency range
Over voltage category
AC power supply Built-in battery charger Rechargeable batteries (NiMH) Battery life (tipically) Weight
Dimensions (mm)
Accessories: page 4.22
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