AMETEK CTS 3.0 - Manual (Page 73)

User Manual Compliance Test System 3.0
69
Balanced
Three Phase
Equipment?
Portable
Power
Tool?
Lighting
Equipment?
P<600W
& special
waveshape
CLASS B
CLASS C
Yes
Yes
No
No
No
Motor
Driven?
No
CLASS D CLASS A
No Yes
Yes
Start here
Yes
The exact IEC 61000-3-2:1998 standard text is
as follows:
“..equipment�shall�be�deemed�to�be�Class�D�if,�under�
the test conditions given in Annex C, the input current
waveshape of each half period - referred to its peak
value i
pk
- is within the envelope shown in the following
figure for at least 95 % of the duration of each half
period; this implies that waveforms having small peaks
outside the envelope are considered to fall within the
envelope. The center line M, coincides with the peak
value�of�the�input�current.”
A device that does not meet these class D
requirements defaults to a class A device and
should be tested against the class A limits.
The flowchart shown in Figure 5-2 can be used to
determine the class of the device to be tested.
When selecting IEC 61000-3-2:1998 mode with a
Class D device, the CTS Software will display the
current waveshape and the special waveform
template. The percentage that fails within the
template is displayed as well. If the waveform is
not class D, the user will be given an indication.
The test can still be run however. In Class A
testing, the special waveform check is also
performed to prevent a “False Positive”.
If the CTS software indicates that the current waveform does not meet the Class D requirements,
the user should switch to Class A instead.
5.3.2 Dynamic Class C and D Limits
Harmonic current limits for Class D are a function of the EUT power level. This poses an
interesting problem, especially if the device has a fluctuating power draw pattern. This means the
test limits change with the power consumption of the EUT. While there is some discussion in the
IEC community regarding the practicality of using such dynamic test limits, the CTS software is
fast enough to dynamically recalculate the test limits applied to the current harmonics for each
acquisition window of 16 signal periods. As such, the CTS system fully implements the IEC
standard with respect to class D.
The same issue applies to the third harmonic limit for Class C products, which is a function of the
fundamental current and power factor ( ). The CTS software determines the fundamental current
and power factor of the load for each acquisition window and dynamically determines the correct
3
rd
harmonic current limit for Class C devices.
If you select to test to Amendment 14, you will have to enter the manufacturer rated power for
Class D (TV's, PC's and PC Monitors) or the fundamental current and power factor for Class C
(lighting products) instead. The rated values will be used to calculate the Class C and D limits as
long as the actual measured values do not differ from the rated values by more than 10 % during
the test.
Figure 5-2: EUT Class Determination Flowchart