Atec Noiseken-VDS-2002 - Manual (Page 5)

VDS-2002 Voltage Dip and Up Simulator
Test levels
The voltages in this standard use the rated voltage for the equipment (U
T
) as a basis for voltage test level specifications. If the
equipment has a specified input voltage range, then testing should be performed at the lower and upper limits of the voltage range
specified. However, in practice it is only necessary to perform the tests at the lowest specified input voltage, since all the tests
concern a reduction or interruption of supply voltages. "X" is an open duration. One or more of the above test levels and durations
may be chosen.
IEC61000-4-11 is a basic EMC standard defining test generator, methods and others and does not specify particular test levels and
durations, but it is the Generic Immunity standards, as well as the Product family standards, that specify the test revel and pass/fail
performance criteria applied to a particular class of equipment.
For an open set of duration, the IEC standard says other values may be taken in a justified case and shall be specified in product
specifications. For possible future requirements, VDS-2002 has provisions of a variable slew rate from 1s to 10s (0~100% output)
Characteristics of the test generator
Peak inrush current drive capability (not required for voltage variation tests)
500A for 220V-240V mains
250A for 100V-120V mains
The test generator has to simulate the very low output impedance characteristics of the real world mains. In other words, the
generator must be able to provide inrush currents of a similar level to the actual power mains.
Most electronic products such as those using switching power supplies exhibit high start up currents needed to charge capacitive
input circuitry in their input section. Conventional AC amplifiers cannot meet this requirement, and worse yet, they perform as
external soft-start circuits for the EUT. For verifications, the generator shall be switched from 0% to 100% of full output, when driving
a load consisting of an uncharged capacitor whose value is 1700
ȐF in series with a suitable rectifier. A bleeder resistor in a range of
100 ohm to 10k ohm shall be connected in parallel with the capacitor. Several time constants must be allowed between tests. The
standard specifies the current monitor's characteristics used to measure peak inrush current capability.
Overshoot/Undershoot (loaded with 100 ohms) :
 5%
Voltage rise/fall time (for abrupt change, generator loaded with 100 ohms): 1 to 5
Ȑs.
Conventional AC amplifiers cannot meet
this requirement
Phase shifting: 0 to 360
f
Execution of test
3 dips/interruptions/variations with interval of 10s minimum
Abrupt change in supply voltage shall occur at zero crossing of the voltage.Additional angles (45, 90, 135, 180, 225, 270, 315
f)are
specified for use by product committees or individual product specifications.
The IEC standard requires the monitoring of EUT line voltage within a accuracy of 2%.ALM-21 is suitable for this purpose with its
logging capability. This power Line Monitor also can monitor the VDS output voltages.
ALM-21 accuracy:
ȗ(0.5% rdge0.8V)
IEC 61000-4-11 Standard/Voltage Dips, Short Interruptions and Variations
Test Level
%U
T
Time for
decreasing
voltage
Time at
reduced
voltage
Time for
increasing
voltage
Test Level
%U
T
0
40
70
100 40%U
T
0%U
T
2s
ȗ20%
2s
ȗ20%
1s
ȗ20%
1s
ȗ20%
2s
ȗ20%
2s
ȗ20%
x x x
60
30
Voltage dip and
short interruptions
%U
T
Duration
(in perriod)
0.5
1
5
10
25
50
x