Brief summary of IEC61000-3-3

Laplace Standards

IEC/EN61000-3-3

Limitation of voltage fluctuations and flicker in low-voltagte supply systems for equipment with a rated current <16A.

This standard becomes a mandatory requirement on Jan 1st 2001.

Applicable to all electrical and electronic equipment having an input current up to and including 16 amps per phase and intended to be connected to the public low-voltage mains distribution systems of between 220V and 250V at 50Hz line to neutral. The limits are based on the subjective severity of the flicker imposed on the light from a 230V/60W filament lamp.
Tests shall not be made on equipment that is unlikely to produce significant voltage fluctuations or flicker.
For equipment with a nominal supply voltage less than 220V and/or a frequency of 60Hz the limits have not yet been considered.
Special equipment that is not widely used and is designed in such a way that it is unable to comply with the requirements of this standard may be subject to installation restrictions requiring the consent of the supply authority before connection.

Assessment of flicker is undertaken with a ‘Flickermeter’ which complies with EN60868 (Functional and design specifications) and BS/EN60868-0 (Evaluation of Flicker severity).
Essentially, the flickermeter measures the voltage changes imposed on a specified impedance in series with the mains supply input due to EUT current demand changes.
Limits are then applied to the following parameters:

Short term flicker severity, P_st, evaluated over a short term (minutes)
Long term flicker indicator, P_lt, evaluated over a few hours using successive P_st values.
Relative steady state voltage change, dc
Maximum relative voltage change, dmax
Relative voltage change characteristic, d(t)

Derivation of the above values is complex, requires statistical evaluation and requires reference to various plots/data tables in the standards.

The equipment under test must be driven in the most unfavourable sequence of voltage changes and is monitored for an extended period of time.

The Laplace RFH kit includes all that is required for full compliance testing of products for flicker in accordance with IEC61000-3-3. It includes a harmonics and flicker analyser, PC software and a 1kW clean power source. For products with a rating >1kW, the AC2000 can be used up to 16A per phase. The PC software includes all the analysis functions required for evaluation of the test parameters as detailed above.

AC2000	Mains harmonics analyser. Fully complies with IEC61000-3-3.
AC2000-PC	PC software for display, documentation and archiving of results.
AC1000	1kW power source. Provides a ‘harmonic free’ mains supply to comply with IEC61000-3-2 requirements.

Help in the selection of the appropriate measurement techniques and automatic display of the relevant limit levels are standard features in the software provided with all Laplace EMC analysers. Note The above is for guidance only. Refer to the published standard for definitive details, exclusions and exceptions and detailed test technique.


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