Valhalla Scientific Inc., manufacturers of Digital Power Analyzers, Digital Wattmeters, Harmonic Ppower Analyzers, Wideband Spectral Power Analyzers, ATC Ohmmeters, Micro-Ohmmeters, Milli-Ohmmeters, Digital Ohmmeters, HI-LO Comperators, Igniter Testers, Current Calibrators, AC DC Active Current Shunts, Hipot Testers, Body Comp Scale.


'Manufacturers of Digital Power Analyzers, Digital Wattmeters, Harmonic Power Analyzers, Wideband Spectrum Power Analyzers, ATC Ohmmeters, Micro-Ohmmeters, Milliohm-Meters, Digital Ohmmeters, Igniter Testers, Current Calibrators, AC-DC Active Current Shunts, Hipot Testers, Body Comp Scales and more…'

Power Related Topics & Parameters
Some important concepts in the discussion of Power Analysis are related to Power Factor, Apparent Power and Reactive Power. The following diagrams are helpful for understanding these advanced topics. Power Factor, VA and VARs Diagrams
	Figure A shows the pythagorean vector relationship real power shares with apparent power(VA) and reactive power (VARs).
	Figure B shows the pythagorean relationship a distorted current waveforms rms level shares with its fundamentalfrequency component and its total harmonic content.
	Figure C shows the similar relationship (like figure B) a distorted voltage waveform shares with its fundamental frequency component and its total harmonic content.

International Electrotechnical Commission Harmonic and Flicker Testing The IEC (International Electrotechnical Commission) is the world wide organization that is responsible for developing the electrical standards relating to the consumer and commercial industries. The IEC 1000-3-2 is the standard that relates to the EMC (Electromagnetic compatibility) limits for harmonic currents emissions for equipment with a rated current of less than 16A. The EN 61000-3-2 is the European Union version. The BSEN 61000-3-2 is the United Kingdom version. The IEC 1000-3-3 is the standard that relates to the EMC (Electromagnetic compatibility) limits for voltage fluctuations and flicker in low voltage supply systems for equipment with a rated current of less than 16A. The EN 61000-3-3 is the European Union version. The BSEN 61000-3-3 is the United Kingdom version. Compliance with the EMC Directive becomes mandatory on January 1, 1996 and those responsible for placing a product on the European Market are well advised to review their position. At least that is what was being said before January 1. Now that date has come and gone they moved that mandatory date up. I am not sure exactly when the EMC Directive becomes mandatory but you can bet it is coming and if you want your products to be accepted in the European Market then you will have to make your product Pass all the tests.

Lets discuss harmonics. A harmonic is a multiple of the fundamental. For instance with general consumer power we use a line frequency in the USA of 60 Hertz (@120 VAC). If we are talking about the third harmonic then that would be 60 x 3 or 180 Hertz. Harmonics are generated when the waveform is not sinusoidal or is distorted. One of the main culprits for generating harmonics is the switch-mode power supply. Switch-mode power supplies offer high efficiency, light weight, in a small package, but they are rich in harmonics. The 3rd, 5th , 7th harmonics are all in phase at the peak of the fundamental and join to make the pulse waveform. What is the problem with harmonics? you might ask. Well when it comes to power generation and consumption, if you really want to know what is going on, follow the money. When it comes to power, the electric (utility) company supplies it, and we pay for it. There are three good reasons the power/utility company wants to limit harmonics on the power mains.

1. It affects how Utility companies bill you for the electricity you use. Utility companies charge by the WATT but supply VA¹s. Lower power factor appliances and electric products that have a rectifier circuit at the main power input (switch-mode power supplies) draw current out of phase with the voltage. This effectively reduces the level of True Power (EI cosθ), and the utility company doesn¹t get to charge (billing-wise) as much. 2. All the power we use is derived from a three phase source where the neutral current should be small. When harmonics are introduced the three phases do not cancel and thus neutral lines end up carrying current. This means that the neutral lines need to carry a heavier load than normal which could pose an electric fire hazard. 3. Some smaller hydro-electric generators can even be damaged by harmonics. The objective is to test the equipment under the conditions that will produce the maximum harmonic amplitudes under normal operating conditions for each harmonic component. The first thing we have to do before we start testing is decide which class the piece of equipment falls into. There are four classes: Class A - Power greater than 600 Watts or Balanced three-phase equipment. Class B - Portable power tools. Class C - Lighting Equipment. Class D - Power between 75 and 600 Watts having special waveshape (switch-mode power supplies). Next we have to decide which type of harmonics we need to test for. There are two categories a) Steady-state harmonics (The current distortion does not vary over time) and Fluctuating harmonics (The current distortion does very over time). Be sure to test using the appropriate classification chart. In practical terms there are few pieces of equipment that actually do draw a constant input power. Even the kitchen toaster is microprocessor controlled these days. Use the appropriate class chart.

Some of the things that need to be considered when testing harmonics as follows. Harmonic currents <0.6% of the input current, or less than 5mA are disregarded. If the envelope of the spectrum of harmonics 20th through 40th decrease monotonically, only harmonics 2 through 19 need to be measured. For fluctuating even harmonics from 2 through 10 and odd harmonics from 3 through 19, harmonic amplitudes can be 1.5 times the limit for 15 seconds of any 2.5 minute period. What we need in order to do this testing is an AC Power Source, Data Processor and a Power Analyzer. The total measurement error for steady-state harmonics shall not exceed 5% of the permissible limits or 0.2% of the rated current of the unit under test. For steady-state harmonics the width of the measuring window shall be between 4 and 30 cycles of the fundamental.
FLICKER AND VOLTAGE FLUCTUATION Fluctuation of luminance (Flicker) is when your equipment causes lamps connected to the same supply to pulsate. Its not only annoying to you, but it can trigger seizures especially in people with epilepsy. For evaluation of complex load fluctuations, a flicker meter is used. It simulates the EYE/BRAIN response as defined in IEC 868. Using filters and statistical analysis, two values are produced. Pst is the short-term flicker severity evaluated over a short period(minutes). Plt is the long-term flicker severity evaluated over a long period(Hours). VOLTAGE FLUCTUATIONS

Voltage Fluctuation is a repeatable fluctuating load that causes changes in the supply voltage, which in turn causes flicker. It can be said that Flicker and Voltage Fluctuation is more of a problem in Europe. The USA usually has its industrial parks separated from the residential districts. However, in Europe you might have a block of apartments with a machine shop in the basement. Also the ground return line in Europe usually stops at the sub station. Note that all of these tests need to be done at 230 Volt 50Hz and since there are other tests that can be accomplished with the source, make sure that it is capable of doing the IEC 1000-4-11 testing.

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