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TestingHarmonics and Flicker

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Harmonics & Flicker

Two different test standards:

EN61000-3-2 & EN61000-3-3

1. EN 61000-3-2 controls the level of distortion of the current drawn by all equipment rated up to 16 amps.

2. EN61000-3-3 controls the level of voltages changes that equipment rated up to 16 amps will impose on the ac supply.

• Both standards have evolved over time – Harmonic standard. originally called IEC 555 Part 2 1987– Flicker standard. originally called IEC 555 Part 3 1987 – Now referred to as EN61000-3-2 & EN61000-3-3 Standards– EN is short for Euro Norm; the version enforceable in law in European countries. The

EN is usually identical to the IEC version.

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Current Harmonic Distortion

Most modern power supplies draw current that is non-sinusoidal.

Input Voltage

Input Current

Load

(Charging when input voltage greater than capacitor volts)

Capacitor Voltage

Capacitor Current

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Current Harmonic DistortionThe distorted current causes problems for electricity suppliers, consumers and product manufacturers.

• The extra distorted current drawn does no useful work. The power factor is < 1, or

V x A > WThis means more electricity must be generated, distributed

and paid for than is consumed as useful energy.

• The current distortion leads to to the phenomenon of triplen harmonic currents flowing in the neutral of three-phase systems – a fire risk in large office installations.

• and to voltage distortion that can cause overheating in motors.

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Current Harmonic Distortion

Fourier analysis is used to describe any repetitive waveform in terms of sine-waves that are at multiples of the fundamental frequency.

EN61000-3-2 controls current distortion by setting limits for the amplitude of the 1st 40 current harmonics.

50HZ

100HZ

150HZ

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Requirements of EN61000-4-7

• How to measure to the harmonics is defined by EN61000-4-7

• It is a not a simple requirement. The following measurements must be made:

• Power, Power Factor , Voltage Harmonics, Fundamental Current, POHC (Partial Odd Harmonic Current) as well as Current Harmonics.

• And in a very specific way: NEW REQUIREMENTS

• Measurements are made every 200mS, continuously without gaps.(10 cycles @ 50Hz, 12 cycles @ 60Hz).

• Inter-harmonics must also be measured for current harmonics

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Requirements of EN61000-4-7 t t +

200mS t + 400ms

… … Average Maximum

W 180.56 182.34 184.12 180.05 184.12 V 230.10 230.10 230.10 A 1.21322 1.2542 1.2672 PF 0.6468 0.6318 0.6315 F 49.998 49.999 50.001 AH 01 1.0123 1.0767 1.0854 1.0234 1.0854 AH 02 0.0023 0.0023 0.0024 0.0024 AH 03 0.3129 0.3134 0.3256 0.3256 AH … AH 40 0.0013 0.0013 0.0014 0.0013 0.0014 VH 01 230.05 230.05 230.05 230.05 230.05 VH 02 0.0123 0.0123 0.0123 0.0123 0.0123 VH 03 0.0210 0.0210 0.0210 0.0210 0.0210 VH … VH 40 0.0012 0.0012 0.0012 0.0012 0.0012

• Harmonic measurements every 200mS - 400+ measurements!

• Continuous no-gap analysis• All measurements filtered by 1.5s time-constant filter

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Inter-harmonic groups

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Example Inter-harmonic group

• 6th harmonic (300Hz @ 50Hz)

2 2

2 2 2 2 2 2 2 2 2275 325300 280 285 290 295 300 305 310 315 3202 2

F FG F F F F F F F F F

1/2 1/2

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Applying Limits to Harmonics - EN61000-3-2

• The limits for pass and fail are set by product groups called Classes:

• The limits are different for each harmonic and each of the 4 classes, A, B, C &D

• Class Determination is :-

• If device power is 75-600W and a PC , Monitor or TV then Class D

• If handheld portable tool, then Class B

• If Luminaries then Class C

• If not Class B ,C, or D, or 3 phase then class A.

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Applying Limits to Harmonics - EN61000-3-2

Example Class C limits - calculated from AH01 and PF• Information from the PC Software ‘Help’ system

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Applying Limits to Harmonics - EN61000-3-2

Limit 2

Limit 1

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Applying Limits to Harmonics - EN61000-3-2

Maximum reading Vs Limit 2

Average reading Vs Limit 1

• Limits are set for the average of each harmonic during the test (L1) AND the maximum of each harmonic (L2).

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Flicker - Causes

The AC supply cabling to a building will have a source impedanceAny variation of loads will cause a voltage change at the distribution pointThis fluctuation of voltage will then make the lamps “Flicker”

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Flicker –The Pst = 1 Curve

• The Human tolerance to light flicker is mapped on the Pst = 1curve.• Any point on the curve has the same perceived level of annoyance• Pst = Perceptibility short term

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EN61000-4-15 – The Flickermeter

• For real-life random voltage changes, a flickermeter is used is used to duplicate the human perception of flicker.

• A flickermeter measures rms voltage changes every half-cycle (10ms) and filters the measurements just like the lamp-eye-brain chain.

• The filtered changes are classified to generate a table of the probability that a ‘class’ of voltage change will occur.

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Flicker Pst test results from Voltech software

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Measurement EquipmentThe Harmonics and Flicker standards require fast and accurate analysis of

electrical power quantities:

• Continuous harmonics:• 400+ measurements every 200ms.• Discrete Fourier Transform for a reference instrument.

• Continuous voltage changes:• every 10ms (1/2 cycle@50 Hz), • real-time flickermeter processing.

• Limit checking and reports• Calculation of harmonic limits from averaged and maximum readings• Comparison to different class limits • Recording and presentation of results

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The PM6000

Up to 6 wattmeter channels

Accuracy: 0.02% of reading, 0.05% of range

Bandwidth: 10MHz

Sampling rate: 40 MSPS

Display: Bright color VGA

Connectivity: RS232, IEEE488, Printer, Ethernet

Connectivity (Future Release): PCMCIA for analog I/O including torque and speed, USB

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PM6000 Measurement Channel

DSP200MHz

PCI Bus • Continuous 5

MSPS data from every channel.

•No analysis gaps, no missing data

Pulse Transformers

•Data and control.•Provide superior

CMRR than opto-isolators

A- D Convertor

•14-bit•40MSPS Max•5MSPS Min

Isolation•4kVpk •CMRR:•140dB @ 60Hz•95dB @ 1MHz

i

v

±5V

±12V

•Built on 15+ years of Voltech analog know-how

•Unrivalled accuracy and bandwidth combination

•Layout and timing minimise phase delay for best Watts accuracy

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Why the Voltech PM6000?Processing power to perform discrete Fourier transform (DFT) analysis, harmonics and inter-harmonics every 200mS

Simultaneous voltage, current, power (W) and PF measurements as required

EN61000-4-7 calls for synchronization accuracy of +/- 0.03%.

0.02%

EN61000-4-7 calls for crest factor of up to 4.20

EN61000-4-7 calls for nominal current input overload times 10 for 1 second.

250A

Accuracy of voltage and current measurements 10 to 100 times better than standard requires.

Powerful PC software with comprehensive ‘help’ system

Full compliance tests with an AC source, or accurate pre-compliance from the ac line

20 years of digital power analyzer know-how.

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ReferencesHarmonic Limits

IEC 61000-3-2 -Consol.Ed.2.1 (2001)All electrical and electronic equipment up to 16A. 220 to 240V 50 or 60Hz.IEC 61000-3-12.All electrical and electronic equipment rated 16A to 75A. 230/400V 50 or 60Hz.

Harmonic Measuring EquipmentIEC 61000-4-7 (2002)- 200ms window and Interharmonics requirement mandatory end 2007

Flicker LimitsIEC 61000-3-3 -Consol.Ed.1.1 (2001)All electrical and electronic equipment up to 16A. 220 to 250V line to neutral at 50Hz.IEC 61000-3-11 Ed.1 (2000)All electrical and electronic equipment 16A to 75A. 220 to 250V 50Hz.

FlickermetersIEC 61000-4-15 Ed.1.1.(2003)

Help informationVoltech IEC61000 software for the PM6000.Standards from: www.iec.ch Software from: www.voltech.com (free download).

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End of Presentation

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