Download A.2 Test conditions for lighting equipments

Part 3 LimitsSection 3 : Limition of voltage fluctuations and
flicker In low-voltage supply systems for
equipment with rated current <16A
Group 7A
50262339 Wong Yuk Tung
50247510 Ching Chun
50204951 Eddie
Objectives
It specifies limits of voltage changes which
may be produced by an equipment tested
under specified conditions and gives
guidance on methods of assessment.
Objectives
It is applicable to electrical and electronic
equipment having an input current up to
and including 16A per phase and intended
to be connected to public low-voltage
distribution system of between 220V and
250V at 50Hz line to neutral.
Test Circuit
Voltage Fluctuations and Flicker
Voltage Fluctuation

A series of voltage changes or a continuous
variation of the r.m.s. voltage
Flicker

Impression of unsteadiness of visual
sensation induced by a light stimulus whose
luminance or spectral distribution fluctuates
with time.
Assessment of voltage fluctuations and
flicker
1. Assessment of a relative voltage
change, “d”
2. Assessment of the short-term flicker
value,Pst
3. Assessment of long-term flicker
value,Ptt
1. Assessment of a relative voltage change
Voltage change waveform at the terminals
of the EUT
difference ΔU of any 2 successive values
of the phase-to-neutral voltages U(t1) and
U(t2)
ΔU = U(t1) - U(t2)
2. Assessment of the short-term flicker value,
Pst
The flicker severity evaluated over a short
period (in minutes); Pst=1 is the
conventional threshold of irritability
(amendment 1to IEC 868)
Assessment method for Pst
Types of voltage fluctuation
All voltage fluctuations (on-line
evaluation)
All voltage fluctuations where U(t)
is defincd
Volatge change waveform
according to fig. A to C with an
occurrence rate less than 1 per
second
Method of evaluating
Pst
Direct measurement
Simulation
Direct measurement
Analyist method
Simulation
Direct measurement
Rectangular voltage changes Use of the Pst=1
at equal intervals
curve
2.1 Flickermeter
All types of voltage fluctuations may be
assessed by direct measurement using
flickermeter
2.2 Simulation method
When the relative voltage change
waveform d(t) is known, Pst can be
evaluated using a computer simulation.
2.3 Analytical method
Shape factors F for double-step and ramp-voltage
characteristics
2.3 Analytical method
Shape factors F for rectangular and triangular voltage
characteristics
2.3 Analytical method
Shape factors F for motor-start voltage characteristics having various
front times.
2.3 Analytical method
The value of Pst obtained using this
method is expect to be within +/- 10% of
the result which would be obtained by
direct measurement (reference method).
This method is not recommended if the
time duration between the end of one
voltage change and the start of the next is
less than 1s.
2.4 Use of Pst = 1 curve
For rectangular voltage changes of the same
amplitude “d” separated by equal time intervals,
Curve may be used to deduce the amplitude
corresponding to Pst=1 for a particular rate of
repetition;
This amplitude is called dlim.
The Pst value corresponding to the voltage
change “d” is then given by Pst =d/dlim
2.4 Curve for Pst = 1
3. Assessment of long-term flicker value, Plt
The flicker severity evaluated over a long
period (a few hours) using successive Pst
values.
e.g. Lighting equipment

Shall be tested with a lamp of the that power
for which the equipment is rated
6. Test Condition
6.1 General
No need for equipments that are unlikely to
produce significant voltage fluctuations or flicker.
Test setup:
 Test supply voltage
 Reference Impedance
 Equipment Under Test
 Flickermeter if necessary
Test Circuit
6. Test Condition
6.2 Measurement Accuracy
Tolerance

current (I): +/-1%

relative voltage change (d): +/-8% (w.r.t dmax)

total impedance: +/-8% (excluding EUT)
6. Test Condition
6.3 Test Supply Voltage
Test supply voltage (o/c volt) shall be the rated
voltage of EUT.
230V single-phase / 400V three-phase for
equipment stated with voltage range.
Tolerance:
 Voltage: +/-2% of nominal value
 Frequency: 50Hz +/- 0.5%
6. Test Condition
6.5 Observation Period
For all assessments,
(flickermeter, simulation, analytical)
for Pst, Tp = 10mins
for Plt, Tp = 2hrs.
Observation period shall include part of the
whole operation cycle in which the EUT
produces the most unfavorable sequence of
voltage changes.
6. Test Condition
6.5 Observation Period
Short term flicker measurement
 Operation repeated continuously, unless
otherwise specified.
 Also include time to restart the equipment
Long term flicker measurement
 Operation not repeated, unless otherwise
specified.
6. Test Condition
6.6 General Test Conditions
Shall be set to produce most unfavorable result using
only those conditions that are mentioned by the
manufacturer.
For equipment having several controlled circuits


Each circuit is considered as single item if intended to be used
independently.
Group of circuit is considered as single item if intended to used
simultaneously.
For control system regulating part of a load only, the
voltage fluctuation produced by each variable part of the
load alone shall be considered.
5. Limits
Applicable at supply terminal of EUT.
Limits:





The value of Pst shall not be greater than 1.0
The value of Plt shall not be greater than 0.65
The relative steady-state voltage change, dc, shall not
exceed 3%.
The max. relative voltage change, dmax, shall not
exceed 4%
The value of d(t) during a voltage change shall not
exceed 3% for more than 200ms.
The limits do not apply to emergency switching
or emergency interruptions.
Annex A
Application of limits and type test conditions for specific
equipment
A.1 Test conditions for cookers
A.2 Test conditions for lighting equipments
A.3 Test conditions for washing machine
A.4 Test conditions for tumbler dryers
A.5 Test conditions for refrigerators
A.6 Test conditions for copying machines, laser printers and similar
appliances
A.7 Test conditions for vacuum cleaners
A.8 Test conditions for food mixers
A.9 Test conditions for portable tools
A.10 Test conditions for hairdryers
A.11 Test conditions for consumer electronic products
A.12 Test conditions for direct water heaters
Annex A
Application of limits and type test conditions for specific
equipment
A.2 Test conditions for lighting equipment

Pst and Plt are only evaluated for lighting
equipment which is likely produce flicker, for
example, disco lighting
Annex A
Application of limits and type test conditions for specific
equipment
A.9 Test conditions for portable tools


Plt shall not be evaluated.
Pst
Shall be evaluated only when that tool comes with
heating elements.
Operate continuously for 10mins or until it switch
off automatically.
Annex A
Application of limits and type test conditions for specific
equipment
A.11 Test conditions for consumer
electronic products

For consumer electronics products, only the
measurement of dmax is required.
END
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